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Compounds containing manganese as an acid-forming element. Manganese forms two unstable acids, namely, manganic acid and permanganic acid. While these acids are of little interest, some of their salts, especially the permanganates, are important compounds.
Manganic acid and manganates. When manganese dioxide is fused with an alkali and an oxidizing agent a green compound is formed. The equation, when caustic potash is used, is as follows:
MnO{2} + 2KOH + O = K{2}MnO{4} + H{2}O.
The green compound (K{2}MnO{4}) is called potassium manganate, and is a salt of the unstable manganic acid (H{2}MnO{4}). The manganates are all very unstable.
Permanganic acid and the permanganates. When carbon dioxide is passed through a solution of a manganate a part of the manganese is changed into manganese dioxide, while the remainder forms a salt of the unstable acid HMnO_{4}, called permanganic acid. The equation is
3K_{2}MnO_{4} + 2CO_{2} = MnO_{2} + 2KMnO_{4} + 2K_{2}CO_{3}.
Potassium permanganate (KMnO_{4}) crystallizes in purple-black needles and is very soluble in water, forming an intensely purple solution. All other permanganates, as well as permanganic acid itself, give solutions of the same color.
Oxidizing properties of the permanganates. The permanganates are remarkable for their strong oxidizing properties. When used as an oxidizing agent the permanganate is itself reduced, the exact character of the products formed from it depending upon whether the oxidation takes place (1) in an alkaline or neutral solution, or (2) in an acid solution.
1. Oxidation in alkaline or neutral solution. When the solution is either alkaline or neutral the potassium and the manganese of the permanganate are both converted into hydroxides, as shown in the equation
2KMnO_{4} + 5H_{2}O = 2Mn(OH)_{4} + 2KOH + 3O.
2. Oxidation in acid solution. When free acid such as sulphuric is present, the potassium and the manganese are both changed into salts of the acid:
2KMnO_{4} + 3H_{2}SO_{4} = K_{2}SO_{4} + 2MnSO_{4} + 3H_{2}O + 5O.
Under ordinary conditions, however, neither one of these reactions takes place except in the presence of a third substance which is capable of oxidation. The oxygen is not given off in the free state, as the equations show, but is used up in effecting oxidation.
Potassium permanganate is particularly valuable as an oxidizing agent not only because it acts readily either in acid or in alkaline solution, but also because the reaction takes place so easily that often it is not even necessary to heat the solution to secure action. The substance finds many uses in the laboratory, especially in analytical work. It is also used as an antiseptic as well as a disinfectant.
CHROMIUM
Occurrence. The ore from which all chromium compounds are made is chromite, or chrome iron ore (FeCr_{2}O_{4}). This is found most abundantly in New Caledonia and Turkey. The element also occurs in small quantities in many other minerals, especially in crocoisite (PbCrO_{4}), in which mineral it was first discovered.
Preparation. Chromium, like manganese, is very hard to reduce from its ores, owing to its great affinity for oxygen. It can, however, be made by the same methods which have proved successful with manganese. Considerable quantities of an alloy of chromium with iron, called ferrochromium, are now produced for the steel industry.
Properties. Chromium is a very hard metal of about the same density as iron. It is one of the most infusible of the metals, requiring a temperature little short of 3000 deg. for fusion. At ordinary temperatures air has little action on it; at higher temperatures, however, it burns brilliantly. Nitric acid has no action on it, but hydrochloric and dilute sulphuric acids dissolve it, liberating hydrogen.
Compounds containing chromium as a base-forming element. While chromium forms two series of salts, chromous salts are difficult to prepare and are of little importance. The most important of the chromic series are the following:
Chromic hydroxide Cr(OH){3}. Chromic chloride CrCl{3}.6H{2}O. Chromic sulphate Cr{2}(SO{4}){3}. Chrome alums
Chromic hydroxide (Cr(OH)_{3}). This substance, being insoluble, can be obtained by precipitating a solution of the chloride or sulphate with a soluble hydroxide. It is a greenish substance which, like aluminium hydroxide, dissolves in alkalis, forming soluble salts.
Dehydration of chromium hydroxide. When heated gently chromic hydroxide loses a part of its oxygen and hydrogen, forming the substance CrO.OH, which, like the corresponding aluminium compound, has more pronounced acid properties than the hydroxide. It forms a series of salts very similar to the spinels; chromite is the ferrous salt of this acid, having the formula Fe(CrO{2}){2}. When heated to a higher temperature chromic hydroxide is completely dehydrated, forming the trioxide Cr{2}O{3}. This resembles the corresponding oxides of aluminium and iron in many respects. It is a bright green powder, and when ignited strongly becomes almost insoluble in acids, as is also the case with aluminium oxide.
Chromic sulphate (Cr{2}(SO{4}){3}). This compound is a violet-colored solid which dissolves in water, forming a solution of the same color. This solution, however, turns green on heating, owing to the formation of basic salts. Chromic sulphate, like ferric and aluminium sulphates, unites with the sulphates of the alkali metals to form alums, of which the best known are potassium chrome alum (KCr(SO{4}){2}.12H{2}O) and ammonium chrome alum (NH{4}Cr(SO{4}){2}.12H{2}O).
These form beautiful dark purple crystals and have some practical uses in the tanning industry and in photography. A number of the salts of chromium are also used in the dyeing industry, for they hydrolyze like aluminium salts and the hydroxide forms a good mordant.
Hydrolysis of chromium salts. When ammonium sulphide is added to a solution of a chromium salt, such as the sulphate, chromium hydroxide precipitates instead of the sulphide. This is due to the fact that chromic sulphide, like aluminium sulphide, hydrolyzes in the presence of water, forming chromic hydroxide and hydrosulphuric acid. Similarly, a soluble carbonate precipitates a basic carbonate of chromium.
Compounds containing chromium as an acid-forming element. Like manganese, chromium forms two unstable acids, namely, chromic acid and dichromic acid. Their salts, the chromates and dichromates, are important compounds.
Chromates. When a chromium compound is fused with an alkali and an oxidizing agent a chromate is produced. When potassium hydroxide is used as the alkali the equation is
2Cr(OH){3} + 4KOH + 3O = 2K{2}CrO{4} + 5H{2}O.
This reaction recalls the formation of a manganate under similar conditions.
Properties of chromates. The chromates are salts of the unstable chromic acid (H_{2}CrO_{4}), and as a rule are yellow in color. Lead chromate (PbCrO_{4}) is the well-known pigment chrome yellow. Most of the chromates are insoluble and can therefore be prepared by precipitation. Thus, when a solution of potassium chromate is added to solutions of lead nitrate and barium nitrate respectively, the reactions expressed by the following equations occur:
Pb(NO{3}){2} + K{2}CrO{4} = PbCrO{4} + 2KNO{3},
Ba(NO{3}){2} + K{2}CrO{4} = BaCrO{4} + 2KNO{3}.
The chromates of lead and barium separate as yellow precipitates. The presence of either of these two metals can be detected by taking advantage of these reactions.
Dichromates. When potassium chromate is treated with an acid the potassium salt of the unstable dichromic acid (H_{2}Cr_{2}O_{7}) is formed:
2K{2}CrO{4} + H{2}SO{4} = K{2}Cr{2}O{7} + K{2}SO{4} + H{2}O.
The relation between the chromates and dichromates is the same as that between the phosphates and the pyrophosphates. Potassium dichromate might therefore be called potassium pyrochromate.
Potassium dichromate (K_{2}Cr_{2}O_{7}). This is the best known dichromate, and is the most familiar chromium compound. It forms large crystals of a brilliant red color, and is rather sparingly soluble in water. When treated with potassium hydroxide it is converted into the chromate
K{2}Cr{2}O{7} + 2KOH = 2K{2}CrO{4} + H{2}O.
When added to a solution of lead or barium salt the corresponding chromates (not dichromates) are precipitated. With barium nitrate the equation is
2Ba(NO_{3})_{2} + K_{2}Cr_{2}O_{7} + H_{2}O = 2BaCrO_{4} + 2KNO_{3} + 2HNO_{3}.
Potassium dichromate finds use in many industries as an oxidizing agent, especially in the preparation of organic substances, such as the dye alizarin, and in the construction of several varieties of electric batteries.
Sodium chromates. The reason why the potassium salt rather than the sodium compound is used is that sodium chromate and dichromate are so soluble that it is hard to prepare them pure. This difficulty is being overcome now, and the sodium compounds are replacing the corresponding potassium salts. This is of advantage, since a sodium salt is cheaper than a potassium salt, so far as raw materials go.
Oxidizing action of chromates and dichromates. When a dilute solution of a chromate or dichromate is acidified with an acid, such as sulphuric acid, no reaction apparently takes place. However, if there is present a third substance capable of oxidation, the chromium compound gives up a portion of its oxygen to this substance. Since the chromate changes into a dichromate in the presence of an acid, it will be sufficient to study the action of the dichromates alone. The reaction takes place in two steps. Thus, when a solution of ferrous sulphate is added to a solution of potassium dichromate acidified with sulphuric acid, the reaction is expressed by the following equations:
(1) K_{2}Cr_{2}O_{7} + 4H_{2}SO_{4} = K_{2}SO_{4} + Cr_{2}(SO_{4})_{3} + 4H_{2}O + 3O,
(2) 6FeSO_{4} + 3H_{2}SO_{4} + 3O = 3Fe_{2}(SO_{4})_{3} + 3H_{2}O.
The dichromate decomposes in very much the same way as a permanganate does, the potassium and chromium being both changed into salts in which they play the part of metals, while part of the oxygen of the dichromate is liberated.
By combining equations (1) and (2), the following is obtained:
K_{2}Cr_{2}O_{7} + 7H_{2}SO_{4} + 6FeSO_{4} = K_{2}SO_{4} + Cr_{2}(SO_{4})_{3} + 3Fe_{2}(SO_{4})_{3} + 7H_{2}0.
This reaction is often employed in the estimation of iron in iron ores.
Potassium chrome alum. It will be noticed that the oxidizing action of potassium dichromate leaves potassium sulphate and chromium sulphate as the products of the reaction. On evaporating the solution these substances crystallize out as potassium chrome alum, which substance is produced as a by-product in the industries using potassium dichromate for oxidizing purposes.
Chromic anhydride (CrO{3}). When concentrated sulphuric acid is added to a strong solution of potassium dichromate, and the liquid allowed to stand, deep red needle-shaped crystals appear which have the formula CrO{3}.This oxide of chromium is called chromic anhydride, since it combines readily with water to form chromic acid:
CrO{3} + H{2}O = H{2}CrO{4}.
It is therefore analogous to sulphur trioxide which forms sulphuric acid in a similar way:
SO{3} + H{2}O = H{2}SO{4}.
Chromic anhydride is a very strong oxidizing agent, giving up oxygen and forming chromic oxide:
2CrO_{3} = Cr_{2}O_{3} + 3O.
Rare elements of the family. Molybdenum, tungsten, and uranium are three rather rare elements belonging in the same family with chromium, and form many compounds which are similar in formulas to the corresponding compounds of chromium. They can play the part of metals and also form acids resembling chromic acid in formula. Thus we have molybdic acid (H_{2}MoO_{4}), the ammonium salt of which is (NH_{4})_{2}MoO_{4}. This salt has the property of combining with phosphoric acid to form a very complex substance which is insoluble in nitric acid. On this account molybdic acid is often used in the estimation of the phosphoric acid present in a substance. Like chromium, the metals are difficult to prepare in pure condition. Alloys with iron can be prepared by reducing the mixed oxides with carbon in an electric furnace; these alloys are used to some extent in preparing special kinds of steel.
EXERCISES
1. How does pyrolusite effect the decolorizing of glass containing iron?
2. Write the equations for the preparation of manganous chloride, carbonate, and hydroxide.
3. Write the equations representing the reactions which take place when ferrous sulphate is oxidized to ferric sulphate by potassium permanganate in the presence of sulphuric acid.
4. In the presence of sulphuric acid, oxalic acid is oxidized by potassium permanganate according to the equation
C_{2}H_{2}O_{4} + O = 2CO_{2} + H_{2}O.
Write the complete equation.
5. 10 g. of iron were dissolved in sulphuric acid and oxidized to ferric sulphate by potassium permanganate. What weight of the permanganate was required?
6. What weight of ferrochromium containing 40% chromium must be added to a ton of steel to produce an alloy containing 1% of chromium?
7. Write the equation representing the action of ammonium sulphide upon chromium sulphate.
8. Potassium chromate oxidizes hydrochloric acid, forming chlorine. Write the complete equation.
9. Give the action of sulphuric acid on potassium dichromate (a) in the presence of a large amount of water; (b) in the presence of a small amount of water.
CHAPTER XXXI
GOLD AND THE PLATINUM FAMILY
============================================================================== ATOMIC HIGHEST HIGHEST MELTING SYMBOL WEIGHT DENSITY OXIDE CHLORIDE POINT Ruthenium Ru 101.7 12.26 RuO{4} RuCl{4} Electric arc Rhodium Rh 103. 12.1 RhO{2} RhCl{2} Electric arc Palladium Pd 106.5 11.8 PdO{2} PdCl{4} 1500 deg. Iridium Ir 193. 22.42 IrO{2} IrCl{4} 1950 deg. Osmium Os 191. 22.47 OsO{4} OsCl{4} Electric arc Platinum Pt 194.8 21.50 PtO{2} PtCl{4} 1779 deg. Gold Au 197.2 19.30 Au{2}O{3} AuCl{3} 1064 deg. ==============================================================================
The family. Following iron, nickel, and cobalt in the eighth column of the periodic table are two groups of three elements each. The metals of the first of these groups—ruthenium, rhodium, and palladium—have atomic weights near 100 and densities near 12. The metals of the other group—iridium, osmium, and platinum—have atomic weights near 200 and densities near 21. These six rare elements have very similar physical properties and resemble each other chemically not only in the type of compounds which they form but also in the great variety of them. They occur closely associated in nature, usually as alloys of platinum in the form of irregular metallic grains in sand and gravel. Platinum is by far the most abundant of the six.
Although the periodic classification assigns gold to the silver-copper group, its physical as well as many of its chemical properties much more closely resemble those of the platinum metals, and it can he conveniently considered along with them. The four elements gold, platinum, osmium, and iridium are the heaviest substances known, being about twice as heavy as lead.
PLATINUM
Occurrence. About 90% of the platinum of commerce comes from Russia, small amounts being produced in California, Brazil, and Australia.
Preparation. Native platinum is usually alloyed with gold and the platinum metals. To separate the platinum the alloy is dissolved in aqua regia, which converts the platinum into chloroplatinic acid (H{2}PtCl{6}). Ammonium chloride is then added, which precipitates the platinum as insoluble ammonium chloroplatinate:
H{2}PtCl{6} + 2NH{4}Cl = (NH{4}){2}PtCl{6} + 2HCl.
Some iridium is also precipitated as a similar compound. On ignition the double chloride is decomposed, leaving the platinum as a spongy metallic mass, which is melted in an electric furnace and rolled or hammered into the desired shape.
Physical properties. Platinum is a grayish-white metal of high luster, and is very malleable and ductile. It melts in the oxyhydrogen blowpipe and in the electric furnace; it is harder than gold and is a good conductor of electricity. In finely divided form it has the ability to absorb or occlude gases, especially oxygen and hydrogen. These gases, when occluded, are in a very active condition resembling the nascent state, and can combine with each other at ordinary temperatures. A jet of hydrogen or coal gas directed upon spongy platinum is at once ignited.
Platinum as a catalytic agent. Platinum is remarkable for its property of acting as a catalytic agent in a large number of chemical reactions, and mention has been made of this use of the metal in connection with the manufacture of sulphuric acid. When desired for this purpose some porous or fibrous substance, such as asbestos, is soaked in a solution of platinic chloride and then ignited. The platinum compound is decomposed and the platinum deposited in very finely divided form. Asbestos prepared in this way is called platinized asbestos. The catalytic action seems to be in part connected with the property of absorbing gases and rendering them nascent. Some other metals possess this same power, notably palladium, which is remarkable for its ability to absorb hydrogen.
Chemical properties. Platinum is a very inactive element chemically, and is not attacked by any of the common acids. Aqua regia slowly dissolves it, forming platinic chloride (PtCl_{4}), which in turn unites with the hydrochloric acid present in the aqua regia, forming the compound chloroplatinic acid (H_{2}PtCl_{6}). Platinum is attacked by fused alkalis. It combines at higher temperatures with carbon and phosphorus and alloys with many metals. It is readily attacked by chlorine but not by oxidizing agents.
Applications. Platinum is very valuable as a material for the manufacture of chemical utensils which are required to stand a high temperature or the action of strong reagents. Platinum crucibles, dishes, forceps, electrodes, and similar articles are indispensable in the chemical laboratory. In the industries it is used for such purposes as the manufacture of pans for evaporating sulphuric acid, wires for sealing through incandescent light bulbs, and for making a great variety of instruments. Unfortunately the supply of the metal is very limited, and the cost is steadily advancing, so that it is now more valuable than gold.
Compounds. Platinum forms two series of salts of which platinous chloride (PtCl{2}) and platinic chloride (PtCl{4}) are examples. Platinates are also known. While a great variety of compounds of platinum have been made, the substance is chiefly employed in the metallic state.
Platinic chloride (PtCl_{4}). Platinic chloride is an orange-colored, soluble compound made by heating chloroplatinic acid in a current of chlorine. If hydrochloric acid is added to a solution of the substance, the two combine, forming chloroplatinic acid (H_{2}PtCl_{6}):
2HCl + PtCl_{4} = H_{2}PtCl_{6}.
The potassium and ammonium salts of this acid are nearly insoluble in water and alcohol. The acid is therefore used as a reagent to precipitate potassium in analytical work. With potassium chloride the equation is
2KCl + H{2}PtCl{6} = K{2}PtCl{6} + 2HCl.
Other metals of the family. The other members of the family have few applications. Iridium is used in the form of a platinum alloy, since the alloy is much harder than pure platinum and is even less fusible. This alloy is sometimes used to point gold pens. Osmium tetroxide (OsO_{4}) is a very volatile liquid and is used under the name of osmic acid as a stain for sections in microscopy.
GOLD
Occurrence. Gold has been found in many localities, the most famous being South Africa, Australia, Russia, and the United States. In this country it is found in Alaska and in nearly half of the states of the union, notably in California, Colorado, and Nevada. It is usually found in the native condition, frequently alloyed with silver; in combination it is sometimes found as telluride (AuTe_{2}), and in a few other compounds.
Mining. Native gold occurs in the form of small grains or larger nuggets in the sands of old rivers, or imbedded in quartz veins in rocks. In the first case it is obtained in crude form by placer mining. The sand containing the gold is shaken or stirred in troughs of running waters called sluices. This sweeps away the sand but allows the heavier gold to sink to the bottom of the sluice. Sometimes the sand containing the gold is washed away from its natural location into the sluices by powerful streams of water delivered under pressure from pipes. This is called hydraulic mining. In vein mining the gold-bearing quartz is mined from the veins, stamped into fine powder in stamping mills, and the gold extracted by one of the processes to be described.
Extraction. 1. Amalgamation process. In the amalgamation process the powder containing the gold is washed over a series of copper plates whose surfaces have been amalgamated with mercury. The gold sticks to the mercury or alloys with it, and after a time the gold and mercury are scraped off and the mixture is distilled. The mercury distills off and the gold is left in the retort ready for refining.
2. Chlorination process. When gold occurs along with metallic sulphides it is often extracted by chlorination. The ore is first roasted, and is then moistened and treated with chlorine. This dissolves the gold but not the metallic oxides:
Au + 3Cl = AuCl_{3}.
The gold chloride, being soluble, is extracted from the mixture with water, and the gold is precipitated from the solution, usually by adding ferrous sulphate:
AuCl{3} + 3FeSO{4} = Au + FeCl{3} + Fe{2}(SO{4}){3}.
3. Cyanide process. This process depends upon the fact that gold is soluble in a solution of potassium cyanide in the presence of the oxygen of the air. The powder from the stamping mills is treated with a very dilute potassium cyanide solution which extracts the gold:
2Au + 4KCN + H{2}O + O = 2KOH + 2KAu(CN){2}.
From this solution the gold can be obtained by electrolysis or by precipitation with metallic zinc:
2KAu(CN)_{2} + Zn = K_{2}Zn(CN)_{4} + 2Au.
Refining of gold. Gold is refined by three general methods:
1. Electrolysis. When gold is dissolved in a solution of potassium cyanide, and the solution electrolyzed, the gold is deposited in very pure condition on the cathode.
2. Cupellation. When the gold is alloyed with easily oxidizable metals, such as copper or lead, it may be refined by cupellation. The alloy is fused with an oxidizing flame on a shallow hearth made of bone ash, which substance has the property of absorbing metallic oxides but not the gold. Any silver which may be present remains alloyed with the gold.
3. Parting with sulphuric acid. Gold may be separated from silver, as well as from many other metals, by heating the alloy with concentrated sulphuric acid. This dissolves the silver, while the gold is not attacked.
Physical properties. Gold is a very heavy bright yellow metal, exceedingly malleable and ductile, and a good conductor of electricity. It is quite soft and is usually alloyed with copper or silver to give it the hardness required for most practical uses. The degree of fineness is expressed in terms of carats, pure gold being twenty-four carats; the gold used for jewelry is usually eighteen carats, eighteen parts being gold and six parts copper or silver. Gold coinage is 90% gold and 10% copper.
Chemical properties. Gold is not attacked by any one of the common acids; aqua regia easily dissolves it, forming gold chloride (AuCl{3}), which in turn combines with hydrochloric acid to form chlorauric acid (HAuCl{4}). Fused alkalis also attack it. Most oxidizing agents are without action upon it, and in general it is not an active element.
Compounds. The compounds of gold, though numerous and varied in character, are of comparatively little importance and need not be described in detail. The element forms two series of salts in which it acts as a metal: in the aurous series the gold is univalent, the chloride having the formula AuCl; in the auric series it is trivalent, auric chloride having the formula AuCl{3}. Gold also acts as an acid-forming element, forming such compounds as potassium aurate (KAuO{2}). Its compounds are very easily decomposed, however, metallic gold separating from them.
EXERCISES
1. From the method of preparation of platinum, what metal is likely to be alloyed with it?
2. The "platinum chloride" of the laboratory is made by dissolving platinum in aqua regia. What is the compound?
3. How would you expect potassium aurate and platinate to be formed? What precautions would this suggest in the use of platinum vessels?
4. Why must gold ores be roasted in the chlorination process?
CHAPTER XXXII
SOME SIMPLE ORGANIC COMPOUNDS
Division of chemistry into organic and inorganic. Chemistry is usually divided into two great divisions,—organic and inorganic. The original significance of these terms was entirely different from the meaning which they have at the present time.
1. Original significance. The division into organic and inorganic was originally made because it was believed that those substances which constitute the essential parts of living organisms were built up under the influence of the life force of the organism. Such substances, therefore, should be regarded as different from those compounds prepared in the laboratory or formed from the inorganic or mineral constituents of the earth. In accordance with this view organic chemistry included those substances formed by living organisms. Inorganic chemistry, on the other hand, included all substances formed from the mineral portions of the earth.
In 1828 the German chemist Woehler prepared urea, a typical organic compound, from inorganic materials. The synthesis of other so-called organic compounds followed, and at present it is known that the same chemical laws apply to all substances whether formed in the living organism or prepared in the laboratory from inorganic constituents. The terms "organic" and "inorganic" have therefore lost their original significance.
2. Present significance. The great majority of the compounds found in living organisms contain carbon, and the term "organic chemistry," as used at present, includes not only these compounds but all compounds of carbon. Organic chemistry has become, therefore, the chemistry of the compounds of carbon, all other substances being treated under the head of inorganic chemistry. This separation of the compounds of carbon into a group by themselves is made almost necessary by their great number, over one hundred thousand having been recorded. For convenience some of the simpler carbon compounds, such as the oxides and the carbonates, are usually discussed in inorganic chemistry.
The grouping of compounds in classes. The study of organic chemistry is much simplified by the fact that the large number of bodies included in this field may be grouped in classes of similar compounds. It thus becomes possible to study the properties of each class as a whole, in much the same way as we study a group of elements. The most important of these classes are the hydrocarbons, the alcohols, the aldehydes, the acids, the ethereal salts, the ethers, the ketones, the organic bases, and the carbohydrates. A few members of each of these classes will now be discussed briefly.
THE HYDROCARBONS
Carbon and hydrogen combine to form a large number of compounds. These compounds are known collectively as the hydrocarbons. They may be divided into a number of groups or series, each being named from its first member. Some of the groups are as follows:
METHANE SERIES CH_{4} methane C_{2}H_{6} ethane C_{3}H_{8} propane C_{4}H_{10} butane C_{5}H_{12} pentane C_{6}H_{14} hexane C_{7}H_{16} heptane C_{8}H_{18} octane
ETHYLENE SERIES C{2}H{4} ethylene C{3}H{6} propylene C{4}H{8} butylene
BENZENE SERIES C{6}H{6} benzene C{7}H{8} toluene C{8}H{10} xylene
ACETYLENE SERIES C{2}H{2} acetylene C{3}H{4} allylene
Only the lower members (that is, those which contain a small number of carbon atoms) of the above groups are given. The methane series is the most extensive, all of the compounds up to C{24}H{50} being known.
It will be noticed that the successive members of each of the above series differ by the group of atoms (CH_{2}). Such a series is called an _homologous series_. In general, it may be stated that the members of an homologous series show a regular gradation in most physical properties and are similar in chemical properties. Thus in the methane group the first four members are gases at ordinary temperatures; those containing from five to sixteen carbon atoms are liquids, the boiling points of which increase with the number of carbon atoms present. Those containing more than sixteen carbon atoms are solids.
Sources of the hydrocarbons. There are two chief sources of the hydrocarbons, namely, (1) crude petroleum and (2) coal tar.
1. Crude petroleum. This is a liquid pumped from wells driven into the earth in certain localities. Pennsylvania, Ohio, Kansas, California, and Texas are the chief oil-producing regions in the United States. The crude petroleum consists largely of liquid hydrocarbons in which are dissolved both gaseous and solid hydrocarbons. Before being used it must be refined. In this process the petroleum is run into large iron stills and subjected to fractional distillation. The various hydrocarbons distill over in the general order of their boiling points. The distillates which collect between certain limits of temperature are kept separate and serve for different uses; they are further purified, generally by washing with sulphuric acid, then with an alkali, and finally with water. Among the products obtained from crude petroleum in this way are the naphthas, including benzine and gasoline, kerosene or coal oil, lubricating oils, vaseline, and paraffin. None of these products are definite chemical compounds, but each consists of a mixture of hydrocarbons, the boiling points of which lie within certain limits.
2. Coal tar. This product is obtained in the manufacture of coal gas, as already explained. It is a complex mixture and is refined by the same general method used in refining crude petroleum. The principal hydrocarbons obtained from the coal tar are benzene, toluene, naphthalene, and anthracene. In addition to the hydrocarbons, coal tar contains many other compounds, such as carbolic acid and aniline.
Properties of the hydrocarbons. The lower members of the first two series of hydrocarbons mentioned are all gases; the succeeding members are liquids. In some series, as the methane series, the higher members are solids. The preparation and properties of methane and acetylene have been discussed in a previous chapter. Ethylene is present in small quantities in coal gas and may be obtained in the laboratory by treating alcohol (C{2}H{6}O) with sulphuric acid:
C_{2}H_{6}O = C_{2}H_{4} + H_{2}O.
Benzene, the first member of the benzene series, is a liquid boiling at 80 deg..
The hydrocarbons serve as the materials from which a large number of compounds can be prepared; indeed, it has been proposed to call organic chemistry the chemistry of the hydrocarbon derivatives.
Substitution products of the hydrocarbons. As a rule, at least a part of the hydrogen in any hydrocarbon can be displaced by an equivalent amount of certain elements or groups of elements. Thus the compounds CH_{3}Cl, CH_{2}Cl_{2}, CHCl_{3}, CCl_{4} can be obtained from methane by treatment with chlorine. Such compounds are called _substitution products_.
Chloroform (CHCl_{3}). This can be made by treating methane with chlorine, as just indicated, although a much easier method consists in treating alcohol or acetone (which see) with bleaching powder. Chloroform is a heavy liquid having a pleasant odor and a sweetish taste. It is largely used as a solvent and as an anaesthetic in surgery.
Iodoform (CHI_{3}). This is a yellow crystalline solid obtained by treating alcohol with iodine and an alkali. It has a characteristic odor and is used as an antiseptic.
ALCOHOLS
When such a compound as CH_{3}Cl is treated with silver hydroxide the reaction expressed by the following equation takes place:
CH{3}Cl + AgOH = CH{3}OH + AgCl.
Similarly C_{2}H_{5}Cl will give C_{2}H_{5}OH and AgCl. The compounds CH_{3}OH and C_{2}H_{5}OH so obtained belong to the class of substances known as _alcohols_. From their formulas it will be seen that they may be regarded as derived from hydrocarbons by substituting the hydroxyl group (OH) for hydrogen. Thus the alcohol CH_{3}OH may be regarded as derived from methane (CH_{4}) by substituting the group OH for one atom of hydrogen. A great many alcohols are known, and, like the hydrocarbons, they may be grouped into series. The relation between the first three members of the methane series and the corresponding alcohols is shown in the following table:
CH{4} (methane) CH{3}OH (methyl alcohol). C{2}H{6} (ethane) C{2}H{5}OH (ethyl alcohol). C{3}H{8} (propane) C{3}H{7}OH (propyl alcohol).
Methyl alcohol (_wood alcohol_) (CH_{3}OH). When wood is placed in an air-tight retort and heated, a number of compounds are evolved, the most important of which are the three liquids, methyl alcohol, acetic acid, and acetone. Methyl alcohol is obtained entirely from this source, and on this account is commonly called _wood alcohol_. It is a colorless liquid which has a density of 0.79 and boils at 67 deg.. It burns with an almost colorless flame and is sometimes used for heating purposes, in place of the more expensive ethyl alcohol. It is a good solvent for organic substances and is used especially as a solvent in the manufacture of varnishes. It is very poisonous.
Ethyl alcohol (_common alcohol_) (C_{2}H_{5}OH). 1. _Preparation._ This compound may be prepared from glucose (C_{6}H_{12}O_{6}), a sugar easily obtained from starch. If some baker's yeast is added to a solution of glucose and the temperature is maintained at about 30 deg., bubbles of gas are soon evolved, showing that a change is taking place. The yeast contains a large number of minute organized bodies, which are really forms of plant life. The plant grows in the glucose solution, and in so doing secretes a substance known as _zymase_, which breaks down the glucose in accordance with the following equation:
C{6}H{12}O{6} = 2C{2}H{5}OH + 2CO{2}.
Laboratory preparation of alcohol. The formation of alcohol and carbon dioxide from glucose may be shown as follows: About 100 g. of glucose are dissolved in a liter of water in flask A (Fig. 90). This flask is connected with the bottle B, which is partially filled with limewater. The tube C contains solid sodium hydroxide. A little baker's yeast is now added to the solution in flask A, and the apparatus is connected, as shown in the figure. If the temperature is maintained at about 30 deg., the reaction soon begins. The bubbles of gas escape through the limewater in B. A precipitate of calcium carbonate soon forms in the limewater, showing the presence of carbon dioxide. The sodium hydroxide in tube C prevents the carbon dioxide in the air from acting on the limewater. The alcohol remains in the flask A and may be separated by fractional distillation.
2. Properties. Ethyl alcohol is a colorless liquid with a pleasant odor. It has a density of 0.78 and boils at 78 deg.. It resembles methyl alcohol in its general properties. It is sometimes used as a source of heat, since its flame is very hot and does not deposit carbon, as the flame from oil does. When taken into the system in small quantities it causes intoxication; in larger quantities it acts as a poison. The intoxicating properties of such liquors as beer, wine, and whisky are due to the alcohol present. Beer contains from 2 to 5% of alcohol, wine from 5 to 20%, and whisky about 50%. The ordinary alcohol of the druggist contains 94% of alcohol and 6% of water. When this is boiled with lime and then distilled nearly all the water is removed, the distillate being called absolute alcohol.
Commercial preparation of alcohol. Alcohol is prepared commercially from starch obtained from corn or potatoes. The starch is first converted into a sugar known as maltose, by the action of malt, a substance prepared by moistening barley with water, allowing it to germinate, and then drying it. There is present in the malt a substance known as diastase, which has the property of changing starch into maltose. This sugar, like glucose, breaks down into alcohol and carbon dioxide in the presence of yeast. The resulting alcohol is separated by fractional distillation.
Denatured alcohol. The 94% alcohol is prepared at present at a cost of about 35 cents per gallon, which is about half the cost of the preparation of methyl alcohol. The government, however, imposes a tax on all ethyl alcohol which amounts to $2.08 per gallon on the 94% product. This increases its cost to such an extent that it is not economical to use it for many purposes for which it is adapted, such as a solvent in the preparation of paints and varnishes and as a material for the preparation of many important organic compounds. By an act of Congress in 1906, the tax was removed from denatured alcohol, that is alcohol mixed with some substance which renders it unfit for the purposes of a beverage but will not impair its use for manufacturing purposes. Some of the European countries have similar laws. The substances ordinarily used to denature alcohol are wood alcohol and pyridine, the latter compound having a very offensive odor.
Fermentation. The reaction which takes place in the preparation of ethyl alcohol belongs to the class of changes known under the general name of fermentation. Thus we say that the yeast causes the glucose to ferment, and the process is known as alcoholic fermentation. There are many kinds of fermentations, and each is thought to be due to the presence of a definite substance known as an enzyme, which acts by catalysis. In many cases, as in alcoholic fermentation, the change is brought about by the action of minute forms of life. These probably secrete the enzymes which cause the fermentation to take place. Thus the yeast plant is supposed to bring about alcoholic fermentation by secreting the enzyme known as zymase.
Glycerin (C_{3}H_{5}(OH)_{3}). This compound may be regarded as derived from propane (C_{3}H_{8}) by displacing three atoms of hydrogen by three hydroxyl groups, and must therefore be regarded as an alcohol. It is formed in the manufacture of soaps, as will be explained later. It is an oily, colorless liquid having a sweetish taste. It is used in medicine and in the manufacture of the explosives nitroglycerin and dynamite.
ALDEHYDES
When alcohols are treated with certain oxidizing agents two hydrogen atoms are removed from each molecule of the alcohol. The resulting compounds are known as aldehydes. The relation of the aldehydes derived from methyl and ethyl alcohol to the alcohols themselves may be shown as follows:
Alcohols {CH{3}OH Corresponding aldehydes {CH{2}O {C{2}H{5}OH {C{2}H{4}O
The first of these (CH_{2}O) is a gas known as formaldehyde. Its aqueous solution is largely used as an antiseptic and disinfectant under the name of _formalin_. Acetaldehyde (C_{2}H_{4}O) is a liquid boiling at 21 deg..
ACIDS
Like the other classes of organic compounds, the organic acids may be arranged in homologous series. One of the most important of these series is the fatty-acid series, the name having been given to it because the derivatives of certain of its members are constituents of the fats. Some of the most important members of the series are given in the following table. They are all monobasic, and this fact is expressed in the formulas by separating the replaceable hydrogen atom from the rest of the molecule:
H.CHO_{2} formic acid, a liquid boiling at 100 deg.. H.C_{2}H_{3}O acetic acid, a liquid boiling at 118 deg.. H.C_{3}H_{5}O_{2} propionic acid, a liquid boiling at 140 deg.. H.C_{4}H_{7}O_{2} butyric acid, a liquid boiling at 163 deg.. H.C_{16}H_{31}O_{2} palmitic acid, a solid melting at 62 deg.. H.C_{18}H_{35}O_{2} stearic acid, a solid melting at 69 deg..
Formic acid (H.CHO_{2}). The name "formic" is derived from the Latin _formica_, signifying ant. This name was given to the acid because it was formerly obtained from a certain kind of ants. It is a colorless liquid and occurs in many plants such as the stinging nettles. The inflammation caused by the sting of the bee is due to formic acid.
Acetic acid (H.C_{2}H_{3}O_{2}). Acetic acid is the acid present in vinegar, the sour taste being due to it. It can be prepared by either of the following methods.
1. Acetic fermentation. This consists in the change of alcohol into acetic acid through the agency of a minute organism commonly called mother of vinegar. The change is represented by the following equation:
C{2}H{5}OH + 2O = HC{2}H{3}O{2} + H{2}O.
The various kinds of vinegars are all made by this process. In the manufacture of cider vinegar the sugar present in the cider first undergoes alcoholic fermentation; the resulting alcohol then undergoes acetic fermentation. The amount of acetic acid present in vinegars varies from 3 to 6%.
2. From the distillation of wood. The liquid obtained by heating wood in the absence of air contains a large amount of acetic acid, and this can be separated readily in a pure state. This is the most economical method for the preparation of the concentrated acid.
Acetic acid is a colorless liquid and has a strong pungent odor. Many of its salts are well-known compounds. Lead acetate (Pb(C_{2}H_{3}O_{2})_{2}) is the ordinary _sugar of lead_. Sodium acetate (NaC_{2}H_{3}O_{2}) is a white solid largely used in making chemical analyses. Copper acetate (Cu(C_{2}H_{3}O_{2})_{2}) is a blue solid. When copper is acted upon by acetic acid in the presence of air a green basic acetate of copper is formed. This is commonly known as verdigris. All acetates are soluble in water.
Butyric acid (H.C_{4}H_{7}O_{2}). Derivatives of butyric acid are present in butter and impart to it its characteristic flavor.
Palmitic and stearic acids. Ordinary fats consist principally of derivatives of palmitic and stearic acids. When the fats are heated with sodium hydroxide the sodium salts of these acids are formed. If hydrochloric acid is added to a solution of the sodium salts, the free palmitic and stearic acids are precipitated. They are white solids, insoluble in water. Stearic acid is often used in making candles.
Acids belonging to other series. In addition to members of the fatty-acid series, mention may be made of the following well-known acids.
Oxalic acid (H_{2}C_{2}O_{4}). This is a white solid which occurs in nature in many plants, such as the sorrels. Its ammonium salt ((NH_{4})_{2}C_{2}O_{4}) is used as a reagent for the detection of calcium. When added to a solution of a calcium compound the white, insoluble calcium oxalate (CaC_{2}O_{4}) precipitates.
Tartaric acid (H_{2}.C_{4}H_{4}O_{6}). This compound occurs either in a free state or in the form of its salts in many fruits. The potassium acid salt (KHC_{4}H_{4}O_{6}) occurs in the juice of grapes. When the juice ferments in the manufacture of wine, this salt, being insoluble in alcohol, separates out on the sides of the cask and in this form is known as argol. This is more or less colored by the coloring matter of the grape. When purified it forms a white solid and is sold under the name of cream of tartar. The following are also well-known salts of tartaric acid: potassium sodium tartrate (Rochelle salt) (KNaC_{4}H_{4}O_{6}), potassium antimonyl tartrate (tartar emetic) (KSbOC_{4}H_{4}O_{6}).
Cream of tartar baking powders. The so-called cream of tartar baking powders consist of a mixture of cream of tartar, bicarbonate of soda, and some starch or flour. When water is added to this mixture the cream of tartar slowly acts upon the soda present liberating carbon dioxide in accordance with the following equation:
KHC_{4}H_{4}O_{6} + NaHCO_{3} = KNaC_{4}H_{4}O_{6} + H_{2}O + CO_{2}.
The carbon dioxide evolved escapes through the dough, thus making it light and porous.
Citric acid (H{3}.C{6}H{5}O{7}). This acid occurs in many fruits, especially in lemons. It is a white solid, soluble in water, and is often used as a substitute for lemons in making lemonade.
Lactic acid (H.C_{3}H_{5}O_{3}). This is a liquid which is formed in the souring of milk.
Oleic acid (H.C_{18}H_{33}O_{2}). The derivatives of this acid constitute the principal part of many oils and liquid fats. The acid itself is an oily liquid.
ETHEREAL SALTS
When acids are brought in contact with alcohols under certain conditions a reaction takes place similar to that which takes place between acids and bases. The following equations will serve as illustrations:
KOH + HNO_{3} = KNO_{3} + H_{2}O,
CH_{3}OH + HNO_{3} = CH_{3}NO_{3} + H_{2}O.
The resulting compounds of which methyl nitrate (CH_{3}NO_{3}) may be taken as the type belong to the class known as _ethereal salts_, the name having been given them because some of them possess pleasant ethereal odors. It will be seen that the ethereal salts differ from ordinary salts in that they contain a hydrocarbon radical, such as CH_{3}, C_{2}H_{5}, C_{3}H_{5}, in place of a metal.
The nitrates of glycerin (_nitroglycerin_). Nitric acid reacts with glycerin in the same way that it reacts with a base containing three hydroxyl groups such as Fe(OH)_{3}:
Fe(OH)_{3} + 3HNO_{3} = Fe(NO_{3})_{3} + 3H_{2}O,
C_{3}H_{5}(OH)_{3} + 3HNO_{3} = C_{3}H_{5}(NO_{3})_{3} + 3H_{2}O.
The resulting nitrate (C{3}H{5}(NO{3}){3}) is the main constituent of nitroglycerin, a slightly yellowish oil characterized by its explosive properties. Dynamite consists of porous earth which has absorbed nitroglycerin, and its strength depends on the amount present. It is used much more largely than nitroglycerin itself, since it does not explode so readily by concussion and hence can be transported with safety.
The fats. These are largely mixtures of the ethereal salts known respectively as olein, palmitin, and stearin. These salts may be regarded as derived from oleic, palmitic, and stearic acids respectively, by replacing the hydrogen of the acid with the glycerin radical C{3}H{5}. Since this radical is trivalent and oleic, palmitic, and stearic acids contain only one replaceable hydrogen atom to the molecule, it is evident that three molecules of each acid must enter into each molecule of the ethereal salt. The formulas for the acids and the ethereal salts derived from each are as follows:
HC_{18}H_{33}O_{2} (oleic acid) C_{8}H_{6}(C_{18}H_{33}O_{2})_{3}, (olein)
HC_{16}H_{31}O_{2} (palmitic acid) C_{3}H_{5}(C_{16}H_{31}0_{2})_{3} (palmitin)
HC_{18}H_{35}O_{2} (stearic acid) C_{3}H_{5}(C_{18}H_{35}O_{2})_{3} (stearin)
Olein is a liquid and is the main constituent of liquid fats. Palmitin and stearin are solids.
Butter fat and oleomargarine. Butter fat consists principally of olein, palmitin, and stearin. The flavor of the fat is due to the presence of a small amount of butyrin, which is an ethereal salt of butyric acid. Oleomargarine differs from butter mainly in the fact that a smaller amount of butyrin is present. It is made from the fats obtained from cattle and hogs. This fat is churned up with milk, or a small amount of butter is added, in order to furnish sufficient butyrin to impart the butter flavor.
Saponification. When an ethereal salt is heated with an alkali a reaction expressed by the following equation takes place:
C{2}H{5}NO{3} + KOH = C{2}H{5}OH + KNO{3}.
This process is known as saponification, since it is the one which takes place in the manufacture of soaps. The ordinary soaps are made by heating fats with a solution of sodium hydroxide. The reactions involved may be illustrated by the following equation representing the reaction between palmitin and sodium hydroxide:
C{3}H{5}(C{16}H{31}O{2}){3} + 3 NaOH = 3 NaC{16}H{31}O{2} + C{3}H{5}(OH){3}.
In accordance with this equation the ethereal salts in the fats are converted into glycerin and the sodium salts of the corresponding acids. The sodium salts are separated and constitute the soaps. These salts are soluble in water. When added to water containing calcium salts the insoluble calcium palmitate and stearate are precipitated. Magnesium salts act in a similar way. It is because of these facts that soap is used up by hard waters.
ETHERS
When ethyl alcohol is heated to 140 deg. with sulphuric acid the reaction expressed by the following equation takes place:
2C{2}H{5}OH = (C{2}H{5}){2}O + H{2}O.
The resulting compound, (C_{2}H_{5})_{2}O, is ordinary ether and is the most important member of the class of compounds called _ethers_. Ordinarily ether is a light, very inflammable liquid boiling at 35 deg.. It is used as a solvent for organic substances and as an anaesthetic in surgical operations.
KETONES
The most common member of this group is acetone (C{3}H{6}O), a colorless liquid obtained when wood is heated in the absence of air. It is used in the preparation of other organic compounds, especially chloroform.
ORGANIC BASES
This group includes a number of compounds, all of which contain nitrogen as well as carbon. They are characterized by combining directly with acids to form salts, and in this respect they resemble ammonia. They may, indeed, be regarded as derived from ammonia by displacing a part or all of the hydrogen present in ammonia by hydrocarbon radicals. Among the simplest of these compounds may be mentioned methylamine (CH_{3}NH_{2}) and ethylamine (C_{2}H_{5}NH_{2}). These two compounds are gases and are formed in the distillation of wood and bones. Pyridine (C_{5}H_{6}N) and quinoline (C_{9}H_{7}N) are liquids present in small amounts in coal tar, and also in the liquid obtained by the distillation of bones. Most of the compounds now classified under the general name of _alkaloids_ (which see) also belong to this group.
CARBOHYDRATES
The term "carbohydrate" is applied to a class of compounds which includes the sugars, starch, and allied bodies These compounds contain carbon, hydrogen, and oxygen the last two elements generally being present in the proportion in which they combine to form water. The most important members of this class are the following:
Cane sugar C{12}H{22}O{11}. Milk sugar C{12}H{22}O{11}. Dextrose C{6}H{12}O{6}. Levulose C{6}H{12}O{6}. Cellulose C{6}H{10}O{5}. Starch C{6}H{10}0{5}.
Cane sugar (C_{12}H_{22}O_{11}). This is the well-known substance commonly called sugar. It occurs in many plants especially in the sugar cane and sugar beet. It was formerly obtained almost entirely from the sugar cane, but at present the greatest amount of it comes from the sugar beet. The juice from the cane or beet contains the sugar in solution along with many impurities. These impurities are removed, and the resulting solution is then evaporated until the sugar crystallizes out. The evaporation is conducted in closed vessels from which the air is partially exhausted. In this way the boiling point of the solution is lowered and the charring of the sugar is prevented. It is impossible to remove all the sugar from the solution. In preparing sugar from sugar cane the liquors left after separating as much of it as possible from the juice of the cane constitute ordinary molasses. Maple sugar is made by the evaporation of the sap obtained from a species of the maple tree. Its sweetness is due to the presence of cane sugar, other products present in the maple sap imparting the distinctive flavor.
When a solution of cane sugar is heated with hydrochloric or other dilute mineral acid, two compounds, dextrose and levulose, are formed in accordance with the following equation:
C{12}H{22}O{11} + H{2}O = C{6}H{12}O{6} + C{6}H{12}O{6}.
This same change is brought about by the action of an enzyme present in the yeast plant. When yeast is added to a solution of cane sugar fermentation is set up. The cane sugar, however, does not ferment directly: the enzyme in the yeast first transforms the sugar into dextrose and levulose, and these sugars then undergo alcoholic fermentation.
When heated to 160 deg. cane sugar melts; if the temperature is increased to about 215 deg., a partial decomposition takes place and a brown substance known as caramel forms. This is used largely as a coloring matter.
Milk sugar (C_{12}H_{22}O_{11}). This sugar is present in the milk of all mammals. The average composition of cow's milk is as follows:
Water 87.17% Casein (nitrogenous matter) 3.56 Butter fat 3.64 Milk sugar 4.88 Mineral matter 0.75
When rennin, an enzyme obtained from the stomach of calves, is added to milk, the casein separates and is used in the manufacture of cheese. The remaining liquid contains the milk sugar which separates on evaporation; it resembles cane sugar in appearance but is not so sweet or soluble. The souring of milk is due to the fact that the milk sugar present undergoes lactic fermentation in accordance with the equation
C_{12}H_{22}O_{11} + H_{2}O = 4C_{3}H_{6}O_{3}.
The lactic acid formed causes the separation of the casein, thus giving the well-known appearance of sour milk.
Isomeric compounds. It will be observed that cane sugar and milk sugar have the same formulas. Their difference in properties is due to the different arrangement of the atoms in the molecule. Such compounds are said to be isomeric. Dextrose and levulose are also isomeric.
Dextrose (_grape sugar, glucose_) (C_{6}H_{12}O_{6}). This sugar is present in many fruits and is commonly called grape sugar because of its presence in grape juice. It can be obtained by heating cane sugar with dilute acids, as explained above; also by heating starch with dilute acids, the change being as follows:
C_{6}H_{10}6_{5} + H_{2}O = C_{6}H_{12}O_{6}.
Pure dextrose is a white crystalline solid, readily soluble in water, and is not so sweet as cane sugar. In the presence of yeast it undergoes alcoholic fermentation. It is prepared from starch in large quantities, and being less expensive than cane sugar, is used as a substitute for it in the manufacture of jellies, jams, molasses, candy, and other sweets. The product commonly sold under the name of glucose contains about 45% of dextrose.
Levulose _(fruit sugar)_(C_{6}H_{12}O_{6}). This sugar is a white solid which occurs along with dextrose in fruits and honey. It undergoes alcoholic fermentation in the presence of yeast.
Cellulose (C_{6}H_{10}O_{5}). This forms the basis of all woody fibers. Cotton and linen are nearly pure cellulose. It is insoluble in water, alcohol, and dilute acids. Sulphuric acid slowly converts it into dextrose. Nitric acid forms nitrates similar to nitroglycerin in composition and explosive properties. These nitrates are variously known as nitrocellulose, pyroxylin, and gun cotton. When exploded they yield only colorless gases; hence they are used especially in the manufacture of smokeless gunpowder. _Collodion_ is a solution of nitrocellulose in a mixture of alcohol and ether. _Celluloid_ is a mixture of nitrocellulose and camphor. _Paper_ consists mainly of cellulose, the finer grades being made from linen and cotton rags, and the cheaper grades from straw and wood.
Starch (C_{6}H_{10}O_{5}). This is by far the most abundant carbohydrate found in nature, being present especially in seeds and tubers. In the United States it is obtained chiefly from corn, nearly 80% of which is starch. In Europe it is obtained principally from the potato. It consists of minute granules and is practically insoluble in cold water. These granules differ somewhat in appearance, according to the source of the starch, so that it is often possible to determine from what plant the starch was obtained. When heated with water the granules burst and the starch partially dissolves. Dilute acids, as well as certain enzymes, convert it into dextrose or similar sugars. When seeds germinate the starch present is converted into soluble sugars, which are used as food for the growing plant.
Chemical changes in bread making. The average composition of wheat flour is as follows:
Water. 13.8% Protein (nitrogenous matter) 7.9 Fats 1.4 Starch 76.4 Mineral matter 0.5
In making bread the flour is mixed with water and yeast, and the resulting dough set aside in a warm place for a few hours. The yeast first converts a portion of the starch into dextrose or a similar sugar, which then undergoes alcoholic fermentation. The carbon dioxide formed escapes through the dough, making it light and porous. The yeast plant thrives best at about 30 deg.; hence the necessity for having the dough in a warm place. If the temperature rises above 50 deg., the vitality of the yeast is destroyed and fermentation ceases. In baking the bread, the heat expels the alcohol and also expands the bubbles of carbon dioxide caught in the dough, thus increasing its lightness.
SOME DERIVATIVES OF BENZENE
Attention has been called to the complex nature of coal tar. Among the compounds present are the hydrocarbons, benzene, toluene, naphthalene, and anthracene. These compounds are not only useful in themselves but serve for the preparation of many other important compounds known under the general name of coal-tar products.
Nitrobenzene (_oil of myrbane_) (C_{6}H_{5}NO_{2}). When benzene is treated with nitric acid a reaction takes place which is expressed by the following equation:
C_{6}H_{6} + HNO_{3} = C_{6}H_{5}NO_{2} + H_{2}O.
The product C_{6}H_{5}NO_{2} is called nitrobenzene. It is a slightly yellowish poisonous liquid, with a characteristic odor. Its main use is in the manufacture of aniline.
Aniline (C_{6}H_{5}NH_{2}). When nitrobenzene is heated with iron and hydrochloric acid the hydrogen evolved by the action of the iron upon the acid reduces the nitrobenzene in accordance with the following equation:
C_{6}H_{5}NO_{2} + 6H = C_{6}H_{5}NH_{2} + 2H_{2}O.
The resulting compound is known as aniline, a liquid boiling at 182 deg.. When first prepared it is colorless, but darkens on standing. Large quantities of it are used in the manufacture of the aniline or coal-tar dyes, which include many important compounds.
Carbolic acid (C{6}H{5}OH). This compound, sometimes known as phenol, occurs in coal tar, and is also prepared from benzene. It forms colorless crystals which are very soluble in water. It is strongly corrosive and very poisonous.
Naphthalene and anthracene. These are hydrocarbons occurring along with benzene in coal tar. They are white solids, insoluble in water. The well-known moth balls are made of naphthalene. Large quantities of naphthalene are used in the preparation of indigo, a dye formerly obtained from the indigo plant, but now largely prepared by laboratory methods. Similarly anthracene is used in the preparation of the dye alizarin, which was formerly obtained from the madder root.
THE ALKALOIDS
This term is applied to a group of compounds found in many plants and trees. They all contain nitrogen, and most of them are characterized by their power to combine with acids to form salts. This property is indicated by the name alkaloids, which signifies alkali-like. The salts are soluble in water, and on this account are more largely used than the free alkaloids, which are insoluble in water. Many of the alkaloids are used in medicine, some of the more important ones being given below.
Quinine. This alkaloid occurs along with a number of others in the bark of certain trees which grow in districts in South America and also in Java and other tropical islands. It is a white solid, and its sulphate is used in medicine in the treatment of fevers.
Morphine. When incisions are made in the unripe capsules of one of the varieties of the poppy plant, a milky juice exudes which soon thickens. This is removed and partially dried. The resulting substance is the ordinary opium which contains a number of alkaloids, the principal one being morphine. This alkaloid is a white solid and is of great service in medicine.
Among the other alkaloids may be mentioned the following: Nicotine, a very poisonous liquid, the salts of which occur in the leaves of the tobacco plant; cocaine, a crystalline solid present in coca leaves and used in medicine as a local anaesthetic; atropine, a solid present in the berry of the deadly nightshade, and used in the treatment of diseases of the eye; strychnine, a white, intensely poisonous solid present in the seeds of the members of the Strychnos family.
INDEX
Acetaldehyde 405
Acetic acid 406
Acetone 411
Acetylene 203 series 399
Acids 106 binary 113 characteristics 106 definition 107 dibasic 159 familiar 106 monobasic 159 nomenclature 113 organic 405 preparation 141 strength 111 ternary 113 undissociated 107
Acker furnace, 279
Agate 260
Air 83 a mechanical mixture 89 carbon dioxide in 87 changes in composition 87 liquid 91 nitrogen in 87 oxygen in 85 poisonous effects of exhaled 88 properties 90 quantitative analysis of 85 regarded as an element 83 standard for density 229 water vapor in 87
Alabaster 308
Alchemists 9
Alchemy 9
Alcohol, common 402 denatured 404 ethyl 402 methyl 402 wood 402
Alcohols 401
Aldehydes 405
Alizarin 418
Alkali 107, 274 family 274
Alkaline-earth family 300
Alkaloids 418
Allotropic forms 22
Alloys 252
Alum 333 ammonium 334 ammonium chrome 384 ammonium iron 352 baking powders 335 potassium 333 potassium chrome 384 potassium iron 352
Aluminates 332
Aluminium 327 bronze 330, 359 chloride 333 family 327 hydroxide 332 metallurgy 328 occurrence 327 oxide 331 preparation 328 properties 329 silicates 335 uses 330
Amalgam 362
Amethyst 260, 331
Ammonia 123 composition 127 preparation 123 properties 124 uses 125
Ammonium 126 acid carbonate 295 carbonate 295 chloride 294 compounds 294
Ammonium hydrosulphide 296 hydroxide 126 molybdate 388 oxalate 407 sulphate 295 sulphide 295 sulphide, yellow 296
Analysis 40
Anhydride 135 carbonic 206 chromic 387 nitric 135 nitrous 135 phosphoric 243 sulphuric 153
Anhydrite 288
Aniline 417
Anion 106
Anode 99
Anthracene 418
Antimony 250 acids 251 alloys 253 chloride 252 metallic properties 252 occurrence 251 oxides 251 preparation 251 properties 251 sulphides 251
Apatite 175, 239, 311
Aqua ammonia 124
Aqua regia 185
Aqueous tension 25
Argon 80
Arsenic 246 acids 250 antidote 250 Marsh's test 248 occurrence 246 oxides 249 preparation 246 properties 247 sulphides 250 white 249
Arsenopyrites 246
Arsine 247
Asbestos 321, 336
Atmosphere 83 constituents 83 function of constituents 84
Atomic hypothesis 61 theory 59 and laws of matter 63 and radium 314 weights, 65 accurate determination 231 and general properties 167 and specific heats 233 calculation of 231 Dalton's method 223 direct determination 233 from molecular weights 230 relation to equivalent 224 standard for 66 steps in determining 224
Atoms 62 size 65
Atropine 419
Aurates 396
Avogadro's hypothesis 226 and chemical calculations 235 and molecular weights 227
Azote 78
Azurite 357
Babbitt metal 253
Bacteria 85 decomposition of organic matter by 122 nitrifying 85
Baking powders 285, 408 alum 335 soda 285
Barium 312 chloride 313 nitrate 313 oxides 312 sulphate 313
Barytes 312
Bases 107 characteristics 107 definition 108 familiar 107 nomenclature 113 organic 412 strength 113 undissociated 108
Basic lining process 346
Bauxite 332
Beer 404
Benzene 417 derivatives 417 series 399
Benzine 400
Bessemer process 345
Bismuth 253 basic salts 255 chloride 253 nitrate 253 occurrence 253 oxides 254 preparation 253 salts, hydrolysis of 254 subnitrate 256 uses 253
Bismuthyl chloride 256
Blast furnace 341 lamp 38
Bleaching powder 306
Bleaching by chlorine 181 by sulphurous acid 152
Boiler scale 320
Bone ash 311
Bone black 200
Borax 265 bead 266
Bornite 357
Boron 257, 264 acids 265 fluoride 264 hydride 264 occurrence 264 oxides 264 preparation 264 properties 264
Brass 323
Bread making 416
Bromides 190
Bromine 187 occurrence 187 oxygen compounds 190 preparation 187 properties 188
Bronze 359 aluminium 330, 359
Butter fat 410
Butyric acid 407
By-product 284
Cadmium 325 compounds 326
Caesium 294
Calamine 321
Calcite 305
Calcium 301 carbide 203, 310 carbonate 305 chloride 306 fluoride 308 hydroxide 303 occurrence 301 oxide 302 phosphate 246, 311 preparation 302 sulphate 308
Calomel 363
Calorie 76
Caramel 414
Carbohydrates 413
Carbolic acid 417
Carbon 196 allotropic forms 196 amorphous 198 compounds 196 crystalline forms 197 cycle in nature 88 dioxide 204 and bases 206 and plant life 88 in air 87 occurrence 204 preparation 204 properties 204 solid 204 disulphide 160, 210 family 196 hydrogen compounds 201 monoxide 208 occurrence 196 oxides 203 properties 200 pure 198 retort 199 uses 200
Carbonates 207 acid 207
Carbonic acid 206
Carborundum 259
Carnallite 288
Casein 414
Cassiterite 370
Catalysis 153
Catalyzers 153
Cathode 99
Cation 106
Caustic potash 288 soda 278
Celestite 312
Celluloid 415
Cellulose 415
Cement 304
Ceramic industries 336
Cerium 377
Chalcedony 260
Chalcocite 357
Chalcopyrite 357
Chalk 305
Chamber acid 157
Changes, physical and chemical 2
Charcoal 199
Chemical affinity 12 changes 2 compounds 7 equilibrium 128 properties 3
Chemistry, definition 4
Chili saltpeter 191, 285
Chinaware 336
Chloric acid 187
Chlorides 186
Chlorine 177 bleaching action 181 chemical properties 180 family 174 historical 177 occurrence 178 oxides 187 oxygen acids 187 preparation 178 properties 179
Chloroform 401
Chloroplatinic acid 393
Chlorous acid 187
Chromates 385
Chrome alum 384
Chromic acid 388 anhydride 387 chloride 383 hydroxide 383 sulphate 384 sulphide 384
Chromite 383
Chromium 383 a base-forming element 383 an acid-forming element 385 occurrence 383
Cinnabar 363
Citric acid 408
Clay 336
Coal 199 gas 217 products 400 tar 218
Cobalt 354 compounds 354
Cocaine 419
Coke 199
Collodion 415
Colemanite 265
Combining weights 225
Combustion 17 broad sense 20 in air 19 phlogiston theory 19 products 18 spontaneous 20 supporters 213
Compounds, chemical 7 isomeric 414 of metals, preparation 265 structure of 118
Conservation of energy 4 of matter 5
Contact process 154
Converter, Bessemer 345
Copper 357 acetate 407 alloys of 359 family 356 hydroxide 360 metallurgy 357 occurrence 357 ores 357 oxide 360 properties 358 refining 358 sulphate 361 sulphide 361 uses 359
Copperas 350
Coral 305
Corrosive sublimate 363
Corundum 331
Cream of tartar 408
Crocoisite 383
Cryolite 175, 328
Crystallization 98 water of 54, 75
Crystallography 161
Crystals 161 axes of 161 systems 162
Cupric compounds 360
Cuprite 360
Cuprous compounds 360 chloride 360 oxide 360
Cyanides 210 solutions are alkaline 210
Dalton's atomic hypothesis 61
Decay 21
Decomposition of organic matter 122
Decrepitation 55
Deliquescence 55
Density of gases 230
Desiccating agents 55
Developers 367
Dewar bulb 91
Dextrose 414
Diamond 197
Dichromates 385
Dichromic acid 385
Dimorphous substances 163
Dissociation 99 and boiling point 101 and freezing point 101 equations of 112 extent of 113
Distillation 50
Dogtooth spar 306
Dolomite 319
Double decomposition 71
Drummond light 38
Dyeing 333
Dynamite 409
Earth metals 327
Efflorescence 54
Electric furnace 221
Electro-chemical industries 269
Electrode 99
Electrolysis 99 of sodium chloride 102 of sodium sulphate 103 of water 41, 102
Electrolytes 99
Electrolytic dissociation 99
Electroplating 366
Electrotyping 359
Elements, definition 8 atomic weights 232 earlier classification 165 names 11 natural groups 165 number of 9 occurrence 10 periodic division 166 physical state 10 symbols of 11
Emery 331
Energy 4 and plant life 89 chemical 5 conservation of 4 transformation of 5
Enzyme 405
Epsom salts 320
Equations 68 are quantitative 72 knowledge requisite for 69 not algebraic 74 reading of 69
Equilibrium 138 chemical 138 in solution 139 point of 138
Equivalent 224 determination of 224 elements with more than one 225 relation to atomic weight 224
Etching 177
Ether 411
Ethereal salts 409
Ethers 411
Ethylamine 412
Ethylene series 399
Eudiometer 43
Evaporation 11
Families in periodic groups 170 triads 165
Family resemblances 170
Fats 409
Fatty acid series 405
Feldspar 261, 335
Fermentation 404 acetic 406 alcoholic 404, 405 lactic 414
Ferric chloride 352 hydroxide 352 salts 351 reduction 353 sulphate 352
Ferrochromium, 383
Ferromanganese 343
Ferrosilicon 259
Ferrous carbonate 351 salts 350 oxidation of 353 sulphate 350 sulphide 350
Fertilizers 245
Filtration 6, 51 beds 52
Fire damp 202
Flames 213 appearance 214 blowpipe 216 Bunsen 214 conditions for 213 hydrogen 34 luminosity 216 oxidizing 214 oxyhydrogen 37 reactions 296 reducing 214 structure 214
Flash lights 317
Flint 260
Fluorides 177
Fluorine 175
Fluorspar 175, 308
Fluosilicic acid 259
Flux 340
Fool's gold 351
Formaldehyde 405
Formalin 405
Formic acid 406
Formulas 68 how determined 234 structural 119
Fractional distillation 51
Franklinite 321
Fuels 220
Furnace, arc 221 electric 221 resistance 221
Fusion methods 271
Galena 373
Gallium 327
Galvanized iron 323
Gas, collection of 15 coal 217 fuel 217 illuminating 217 measurement of 23 natural 219 purification of 218 water 219
Gases, table 220
Gasoline 400
German silver 323, 359
Germanium 370
Germs, effect of cold on 53 in air 84 in water 52
Glass 262 coloring of 263 etching of 177 molding of 263 nature of 263 varieties 263
Glauber's salt 281
Glazing 336
Glucose 414
Glycerin 405 nitrates of 409
Gold 393 alloys 396 chloride 396 coin 359 extraction of 394 in copper 358 mining 394 occurrence 393 properties 396 refining of 395 telluride 394
Goldschmidt method 269, 330
Gram-molecular weight 236
Granite 336
Graphite 198
Gun cotton 415 metal 359 powder 292
Gypsite 308
Gypsum 308
Halogens 174
Hard water 309
Heat of reaction 75
Helium 80, 314
Hematite 339, 349
Homologous series 398
Hydriodic acid 193
Hydrobromic acid 189
Hydrocarbons 201, 398 properties 400 series 398 substitution products 401
Hydrochloric acid 182 composition 183 oxidation of 185 preparation 182 properties 184 salts 186
Hydrocyanic acid 210
Hydrofluoric acid 176 etching by 177 salts of 177
Hydrogen 28 dioxide 56 explosive with oxygen 35 occurrence 28 preparation from acids 30 preparation from water 28 properties 32 standard for atomic weights 66 standard for molecular weights 227 sulphide 146 uses 38
Hydrolysis 254 conditions affecting 255 partial 255
Hydrosulphuric acid 146
Hydroxyl radical 112
Hypochlorous acid 187
Hypothesis 61 Avogadro's 226 Dalton's 61
Ice manufacture 125
Iceland spar 305
Indigo 418
Indium 327
Insoluble compounds 272
Iodic acid 194
Iodides 193
Iodine 190 oxygen compounds 193 preparation 191 properties 192 tincture 192
Iodoform 192, 401
Ions 100 and electrolytes 104
Iridium 393
Iron 339 alum 352 cast 343 compounds 349 cyanides 352 disulphide 351 family 338 metallurgy 339 occurrence 339 ores 339 oxides 349 pure 348 varieties 342, 347 wrought 343
Jasper 260
Kainite 288
Kaolin 261, 335
Kerosene 400
Ketones 411
Kieserite 288
Kindling temperature 17
Krypton 80
Lactic acid 408
Lampblack 200
Laughing gas 132
Law, definition 61 of Boyle 24 of Charles 23 of combining volumes 194 of conservation of energy 4 of conservation of matter 5, 59 of definite composition 59 of Dulong and Petit 233 of Gay-Lussac 194 of multiple proportion 60 of Raoult 233 periodic 169
Lead 373 acetate 375, 407 alloys 375 basic carbonate 376 carbonate 376 chloride 377 chromate 377 insoluble compounds 376 metallurgy 373 nitrate 375 occurrence 373 oxides 375 peroxide 375 properties 374 red 375 soluble salts 375 sugar of 375 sulphate 377 sulphide 377 white 376
Le Blanc soda process 282
Levulose 415
Lime 302 air-slaked 303 hypochlorite 307 kilns 303 slaked 303
Lime light 38
Limestone 305
Limewater 303
Limonite 339
Litharge 375
Lithium 294
Luminosity of flames 216
Lunar caustic 366
Magnesia 318 alba 319 usta 318
Magnesite 318
Magnesium 317 basic carbonate 319 carbonate 318 cement 318 chloride 319 family 316 hydroxide 318 oxide 318 silicates 321 sulphate 320
Magnetite 339, 349
Malachite 357
Manganates 381
Manganese 379 a base-forming element 380 an acid-forming element 381 in glass 263 occurrence 379 oxides 380
Manganic acid 381
Manganous salts 380
Marble 305
Marl 305
Marsh gas 202
Matches 242
Matte 358
Matter, classification 6 conservation 5 definition 5 kinds 9
Measurement of gases 23
Mechanical mixtures 6
Meerschaum 321, 336
Mercuric chloride 363 iodide 364 oxide 14, 362 sulphide 363
Mercurous chloride 363
Mercury 361 iodides 364 metallurgy 361 occurrence 361 oxides 362 uses 362
Metaboric acid 265
Metallurgy 268
Metals 165, 267 action on salts 271 definition 267 extraction 268 occurrence 267 preparation of compounds 269 reduction from ores 268
Metaphosphoric acid 245
Metarsenic acid 250
Metasilicic acid 261
Metastannic acid 371
Methane 202, 399
Methylamine 412
Mexican onyx 305
Mica 261, 336
Microcosmic salt 244
Milk 414
Minerals 267
Minium 375
Mixed salts 244
Molasses 413
Molecular weights 226 boiling-point method 233 compared with oxygen 228 determination 226 freezing-point method 233 oxygen standard 227 of elements 232 vapor-density method 229
Molecule 62
Molybdenum 388
Molybdic acid 388
Monazite sand 377
Mordants 333
Morphine 418
Mortar 304
Moth balls 418
Muriatic acid 182
Naphthalene 418
Naphthas 400
Nascent state 182
Natural gas 219 sciences 1
Neon 80
Neutralization 108 a definite act 109 definition 109 heat of 109 partial 111
Niagara Falls 269, 329
Nickel 354 coin 359 compounds 354 plating 354
Nicotine 419
Nitrates 131
Nitric acid, 128 action on metals 130 decomposition 129 oxidizing action 130 preparation 128, 140 properties 129 salts 131
Nitric oxide 133
Nitrites 132
Nitrobenzene 417
Nitrocellulose 415
Nitrogen 78 compounds 122 in air 87 occurrence 78, 122 oxides 132 preparation 78 properties 80
Nitroglycerin 409
Nitrosulphuric acid 155
Nitrous acid 132 oxide 132
Non-metals 165
Oil of myrbane 417 of vitriol 154
Oleic acid 408
Olein 409
Oleomargarine 410
Onyx 260
Opal 260
Open-hearth process 346
Opium 418
Ores 267
Organic bases 412 chemistry 201, 397 matter, decomposition 122
Orpiment 246
Orthoarsenic acid 250
Orthophosphates 244
Orthophosphoric acid 244
Orthosilicic acid 261
Osmic acid 393
Osmium 393 tetroxide 393
Oxalic acid 407
Oxidation 17, 353 definition 18
Oxidizing agent 37
Oxygen 13 and ozone 22 commercial preparation 16 history 13 importance 21 in air estimation, 85 in air function, 84 occurrence 13 preparation 13 properties 16 standard for atomic weights 66 two atoms in molecule 227
Oxyhydrogen blowpipe 37
Ozone 21, 137
Palladium 390
Palmitic acid 407
Palmitin 409
Paraffin 400
Paris green 250
Parkes's method for silver 364
Pearls 305
Perchloric acid 187
Periodic acid 194
Periodic division 166 groups 167 law 169 law, imperfections 172 law, value 171 table 168 table, arrangement 166
Permanent hardness 310
Permanganates 381
Permanganic acid 381
Peroxides 278
Petroleum 399
Pewter 372
Phenol 417
Philosopher's stone 9
Phlogiston 19
Phosphates 245
Phosphine 242
Phosphonium compounds 243
Phosphoric acid 244
Phosphorite 239
Phosphorous acid 244
Phosphorus 239 acids 243 family 238 hydrogen compounds 242 occurrence 239 oxides 243 preparation 239 properties 240 red 241 yellow 240
Photography 367
Physical changes 2 properties 3 properties and periodic groups 171 state 3
Physics 1, 4
Pitchblende 314
Plaster of Paris 308
Platinic chloride 393
Platinized asbestos 391
Platinous chloride 393
Platinum 391 a catalytic agent 152, 392
Pneumatic trough 16
Polyboric acid 265
Polyhalite 288
Polysilicic acids 261
Porcelain 336
Portland cement 304
Potash 293
Potassium 287 acid carbonate 294 acid sulphate 294 acid sulphite 294 alum, aluminium 334 alum, chrome 384 alum, iron 352 and plant life 287 aurate 396 bromide 290 carbonate 293 chlorate 291 chloride 290 chromate 385 cyanide 293 dichromate 386 ferricyanide 352 ferrocyanide 352 hydroxide 288 hydroxide, action of halogens 289 hypochlorite 289 iodide 290 manganate 381 nitrate 291 occurrence 287 permanganate 381 preparation 288 sulphate 294
Precipitated chalk 306
Precipitation 140
Properties, chemical 3 physical 3
Prussic acid 210
Puddling 343 furnace 344
Pyridine 412
Pyrites 351
Pyrolusite 380
Pyrophosphoric acid 245
Quantitative equations 72
Quartz 260
Quicklime 302
Quinine 418
Quinoline 412
Radical 112
Radium 313
Reaction, classes 70 addition 70 completed 139 heat of 75 of decomposition 70 of double decomposition 71 of substitution 70 reversible 137 steps in 131
Realgar 246
Red lead 375 phosphorus 241
Reducing agent 37
Reduction 36, 354
Rennin 414
Resemblances, family 170
Respiration 87
Rhodium 390
Rochelle salts 408
Rouge 349
Rubidium 294
Ruby 331
Ruthenium 390
Rutile 264
Safety lamp 202
Sal ammoniac 294 soda 282
Salt 280
Saltpeter 291 Chili 285
Salts, 109 acid, 112
Salts basic 111 binary 114 characteristics 109 definition 109 insoluble 272 mixed 244 nomenclature 113 normal 112 preparation by precipitation 270
Sand 260
Sandstone 260
Saponification 410
Sapphire 331
Satinspar 308
Scale 320
Schoenite 288
Selenite 308
Selenium 161
Serpentine 320, 336
Shot 247, 375
Siderite 339
Silica 260
Silicates 261
Silicic acids 261
Silicides 259
Silicon 258 acids 261 dioxide 260 fluoride 258 hydride 258
Silver 364 amalgamation process 364 bromide 367 chloride 367 coin 359 German 359 in copper ores 358 iodide 367 metallurgy 364 nitrate 366 oxide 366 parting of 365 refining 365 sulphide 366
Slag 340
Smalt 355
Smithsonite 321
Smokeless powder 293
Soaps 410
Soda ash 284
Soda lime 202
Sodium 276 acetate 407 bicarbonate 285 carbonate 282 carbonate, historical 284 chloride 280 chromates 386 hydrogen carbonate 285 hydroxide 278 hyposulphite 282 iodate 191 nitrate 285 occurrence 276 peroxide 277 phosphates 286 preparation 276 properties 277 sulphate 281 sulphite 281 tetraborate 287 thiosulphate 282
Solder 372, 375
Solubility of gases 95 of solids 96
Solution 94 and chemical action 53 boiling point 98 classes 94 distribution of solids in 98 electrolysis of 99 freezing point 99 of gases in liquids 94 of solids in liquids 96 properties 98 saturated 97 supersaturated 98
Solvay soda process 283
Sombrerite 239
Spectroscope 296
Sphalerite 325
Spiegel iron 343
Spinel 332
Spontaneous combustion 20
Stalactites 305
Stalagmites 305
Standard conditions 23
Stannates 372
Stannic acid 372 chloride 372 oxide 372
Stannous chloride 372
Starch 415
Stassfurt salts 287
Stearic acid 407
Stearin 409
Steel 345 alloys 348 properties 347 tempering of 348 tool 347
Stibine 251
Stibnite 250
Stoneware 336
Strontianite 312
Strontium 312 hydroxide 312 nitrate 312
Structural formulas 119
Structure of compounds 119
Strychnine 419
Substitution 70
Sugars 412 cane 412 fruit 415 grape 414 milk 414
Sulphates 159
Sulphides 148
Sulphites 152 action of acids on 150
Sulphur 143 allotropic forms 144 chemical properties 145 comparison with oxygen 161 dioxide 149 preparation 149 properties 150 extraction 143 flowers of 143 occurrence 143 oxides 149 physical properties 144 trioxide 152 uses 146 varieties 144
Sulphuric acid 154 action as an acid 157 action on metals 157 action on organic matter 158 action on salts 158 action on water 158 fuming 155 manufacture 154 oxidizing action 157 plant 156 properties 157 salts 159
Sulphuric anhydride 153
Sulphurous acid 151
Superphosphate of lime 246
Sylvine 288
Symbols 11
Synthesis 40
Table, alkali metals 274 alkaline-earth metals 300 alloys of copper 359 aqueous tension Appendix B atomic weights Appendix A chlorine family 174 composition of earth's crust 10 composition of fuel gases 220 constants of elements Appendix B copper family 356 elements Appendix A gold and platinum metals 390 hydrocarbons 399 magnesium family 316 manganese and chromium 379 periodic arrangement 168 phosphorus family 238 silicon family 257 solubility of gases in water 95 solubility of salts 96 solubility of salts at different temperatures 97 tin and lead 370 weights of gases Appendix B
Talc 321, 336
Tartar emetic 408
Tartaric acid 408
Tellurium 161
Temporary hardness 309
Ternary acids 113 salts 114
Tetraboric acid 265
Thallium 327
Theory, atomic 61 definition 64 value of 64
Thermite 331
Thio compounds 282
Thiosulphates 159
Thiosulphuric acid 159
Thorium 377
Tin 370 block 371 compounds 372 crystals 372 family 370 foil 371 metallurgy 370 plate 371 properties 371 uses 371
Titanium 257, 264
Topaz 331
Triad families 166
Tungsten 388
Type metal 253, 375
Uranium 388
Valence 116 a numerical property 116 and combining ratios 118 and equations 120 and formulas 120 and periodic groups 162 and structure 118 definition 116 indirectly determined 117 measure of 117 variable 117
Vaseline 400
Venetian red 349
Verdigris 407
Vermilion 363
Vinegar 406
Vitriol, blue 361 green 350 oil of 154 white 324
Volume and aqueous tension 25 and pressure 24 and temperature 23 of combining gases 194
Water 40 a compound 40 and disease 49 catalytic action of 154 chalybeate 351 chemical properties 53 composition 47 composition by volume 44 composition by weight 47 dissociation of 210 distillation of 50 electrolysis of 41, 103 filtration of 51 gas 219 hard 309 historical 40 impurities in 48 in air 87 mineral 49 occurrence 48 of crystallization 54, 75 physical properties 53 purification of 50 qualitative analysis 41 quantitative analysis 42 river 49 sanitary analysis 50 self-purification 53 softening of 310 standard substance 55 synthesis 43 uses of 55
Weights, atomic 65
Welsbach mantles 219, 377
Whisky 404
Wine 404
Witherite 312
Wood alcohol 402 distillation 402
Wood's metal 254
Xenon 80
Yeast 403
Zinc 321 alloys of 323 blende 321 chloride 325 flowers of 322 metallurgy 321 occurrence 321 oxide 324 sulphate 324 sulphide 325 white 324
Zymase, 403
ANNOUNCEMENTS
AN ELEMENTARY STUDY OF CHEMISTRY
By WILLIAM McPHERSON, Professor of Chemistry in Ohio State University, and WILLIAM E. HENDERSON, Associate Professor of Chemistry in Ohio State University.
12mo. Cloth. 434 pages. Illustrated. List price, $1.25; mailing price, $1.40
This book is the outgrowth of many years of experience in the teaching of elementary chemistry. In its preparation the authors have steadfastly kept in mind the limitations of the student to whom chemistry is a new science. They have endeavored to present the subject in a clear, well-graded way, passing in a natural and logical manner from principles which are readily understood to those which are more difficult to grasp. The language is simple and as free as possible from unusual and technical phrases. Those which are unavoidable are carefully defined. The outline is made very plain, and the paragraphing is designed to be of real assistance to the student in his reading.
The book is in no way radical, either in the subject-matter selected or in the method of treatment. At the same time it is in thorough harmony with the most recent developments in chemistry, both in respect to theory and discovery. Great care has been taken in the theoretical portions to make the treatment simple and well within the reach of the ability of an elementary student. The most recent discoveries have been touched upon where they come within the scope of an elementary text. Especial attention has been given to the practical applications of chemistry, and to the description of the manufacturing processes in use at the present time.
EXERCISES IN CHEMISTRY. By WILLIAM McPHERSON and WILLIAM E. HENDERSON. (In press.)
GINN & COMPANY PUBLISHERS
A FIRST COURSE IN PHYSICS
By ROBERT A. MILLIKAN, Associate Professor of Physics, and HENRY G. GALE, Assistant Professor of Physics in The University of Chicago
12mo, cloth, 488 pages, illustrated, $1.25
A LABORATORY COURSE IN PHYSICS
FOR SECONDARY SCHOOLS
By ROBERT A. MILLIKAN and HENRY G. GALE 12mo, flexible cloth, 134 pages, illustrated, 40 cents
This one-year course in physics has grown out of the experience of the authors in developing the work in physics at the School of Education of The University of Chicago, and in dealing with the physics instruction in affiliated high schools and academies.
The book is a simple, objective presentation of the subject as opposed to a formal and mathematical one. It is intended for the third-year high-school pupils and is therefore adapted in style and method of treatment to the needs of students between the ages of fifteen and eighteen. It especially emphasizes the historical and practical aspects of the subject and connects the study very intimately with facts of daily observation and experience.
The authors have made a careful distinction between the class of experiments which are essentially laboratory problems and those which belong more properly to the classroom and the lecture table. The former are grouped into a Laboratory Manual which is designed for use in connection with the text. The two books are not, however, organically connected, each being complete in itself.
All the experiments included in the work have been carefully chosen with reference to their usefulness as effective classroom demonstrations.
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APPENDIX A
LIST OF THE ELEMENTS, THEIR SYMBOLS, AND ATOMIC WEIGHTS
The more important elements are marked with an asterisk
O = 16
*Antimony Sb 120.2 *Argon A 39.9 *Arsenic As 75.0 *Barium Ba 137.4 Beryllium Be 9.1 *Bismuth Bi 208.5 *Boron B 11.0 *Bromine Br 79.96 *Cadmium Cd 112.4 Caesium Cs 132.9 *Calcium Ca 40.1 *Carbon C 12.00 Cerium Ce 140.25 *Chlorine Cl 35.45 *Chromium Cr 52.1 *Cobalt Co 59.0 Columbium Cb 94.0 *Copper Cu 63.6 Erbium Er 166.0 *Fluorine F 19.0 Gadolinium Gd 156.0 Gallium Ga 70.0 Germanium Ge 72.5 *Gold Au 197.2 Helium He 4.0 *Hydrogen H 1.008 Indium In 115.0 *Iodine I 126.97 Iridium Ir 193.0 *Iron Fe 55.9 Krypton Kr 81.8 Lanthanum La 138.9 *Lead Pb 206.9 Lithium Li 7.03 *Magnesium Mg 24.36 *Manganese Mn 55.0 *Mercury Hg 200.0 Molybdenum Mo 96.0 Neodymium Nd 143.6 Neon Ne 20.0 *Nickel Ni 58.7 *Nitrogen N 14.04 Osmium Os 191.0 *Oxygen O 16.00 Palladium Pd 106.5 *Phosphorus P 31.0 *Platinum Pt 194.8 *Potassium K 39.15 Praseodymium Pr 140.5 Radium Ra 225.0 Rhodium Rh 103.0 Rubidium Rb 85.5 Ruthenium Ru 101.7 Samarium Sm 150.3 Scandium Sc 44.1 Selenium Se 79.2 *Silicon Si 28.4 *Silver Ag 107.93 *Sodium Na 23.05 *Strontium Sr 87.6 *Sulphur S 32.06 Tantalum Ta 183.0 Tellurium Te 127.6 Terbium Tb 160.0 Thallium Tl 204.1 Thorium Th 232.5 Thulium Tm 171.0 *Tin Sn 119.0 Titanium Ti 48.1 Tungsten W 184.0 Uranium U 238.5 Vanadium V 51.2 Xenon Xe 128.0 Ytterbium Yb 173.0 Yttrium Yt 89.0 *Zinc Zn 65.4 Zirconium Zr 90.6
APPENDIX B
Tension of Aqueous Vapor expressed in Millimeters of Mercury
TEMPERATURE PRESSURE 16 13.5 17 14.4 18 15.3 19 16.3 20 17.4 21 18.5 22 19.6 23 20.9 24 22.2 25 23.5
Weight of 1 Liter of Various Gases measured under Standard Conditions
Acetylene 1.1614 Air 1.2923 Ammonia 0.7617 Carbon dioxide 1.9641 Carbon monoxide 1.2499 Chlorine 3.1650 Hydrocyanic acid 1.2036 Hydrochloric acid 1.6275 Hydrogen 0.08984 Hydrosulphuric acid 1.5211 Methane 0.7157 Nitric oxide 1.3410 Nitrogen 1.2501 Nitrous oxide 1.9677 Oxygen 1.4285 Sulphur dioxide 2.8596
Densities and Melting Points of Some Common Elements
DENSITY MELTING POINT Aluminium 2.68 640 Antimony 6.70 432 Arsenic 5.73 — Barium 3.75 — Bismuth 9.80 270 Boron 2.45 — Cadmium 8.67 320 Caesium 1.88 26.5 Calcium 1.54 — Carbon, Diamond 3.50 — " Graphite 2.15 — " Charcoal 1.80 — Chromium 7.30 3000 Cobalt 8.55 1800 Copper 8.89 1084 Gold 19.30 1064 Iridium 22.42 1950 Iron 7.93 1800 Lead 11.38 327 Lithium 0.59 186 Magnesium 1.75 750 Manganese 8.01 1900 Mercury 13.596 -39.5 Nickel 8.9 1600 Osmium 22.47 — Palladium 11.80 1500 Phosphorus 1.80 45 Platinum 21.50 1779 Potassium 0.87 62.5 Rhodium 12.10 — Rubidium 1.52 38.5 Ruthenium 12.26 — Silicon 2.35 — Silver 10.5 960 Sodium 0.97 97.6 Strontium 2.50 — Sulphur 2.00 114.8 Tin 7.35 235 Titanium 3.50 — Zinc 7.00 420
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