of anhydrous sodium acetate and soda-lime, according to the re action CH,COONa+ HONa = CH, + CO ONa methane and sodium carbonate being in theory the sole products. Chemically pure methane is obtained by the reduction of methyl iodide, CH,I, in alcoholic solution with copper-coated zinc (Gladstone and Tribe copper-zinc couple). Methane is a colorless and odorless gas, condensable to a liquid under a pressure of 180 atmospheres at -11° C. It boils at -164° and solidifies at -186°. It burns with a pale, faintly lumiminous flame, and forms an explosive mixture with air. Ethane is found in crude petroleum and in natural gas, and may be formed artificially by the action of zinc or sodium upon methyl iodide, as follows: It is a colorless and odorless gas, which can be liquefied at +4° by a pressure of 46 atmospheres. It burns with a pale flame. Propane, normal butane, and normal hexane, all occur in crude petroleum, the latter two especially being present in gasoline and similar light fractions. Normal heptane, in addition to being present in petroleum, occurs in the oil from the Pinus sabiniana, or nut-pine, of California, and under the special name of “abietene" is used as a cleansing and solvent benzine. 34 The hydrocarbons from C1H, on are solid at ordinary temperatures, and make up the bulk of the products known as petrolatum. A mixture of these hydrocarbons of still higher fusing point constitutes the commercial product known as paraffine. The name paraffin (from parum affinis), first applied to the solid products as obtained from bituminous coals, has been applied to the whole series of hydrocarbons to indicate the stable character of these compounds. They are incapable of combining with halogens or taking up any additional hydrogen, are not affected by any of the strong acids in the cold, and only slightly when heated, and are not easily oxidized by chromic acid or potassium permanganate. 3. Pharmaceutically Important Products.-The first of these is Benzinum, U. S. P., and is stated to be "a purified distillate from American pretroleum consisting of hydrocarbons, chiefly of the marsh-gas series (C,H12, CH1), and homologous compounds." It is a transparent, colorless liquid, of neutral reaction, evaporating without residue and leaving no odor, of sp. gr. 0.670 to 0.675 at 15°, and boiling at 50° to 60° C. It is used as a solvent for fats, resins, rubber, and some of the alkaloids. Petrolatum Liquidum, U. S. P., is stated to be "a mixture of hydrocarbons, chiefly of the marsh-gas series, obtained by distilling off the lighter and more volatile portions from petroleum, and purifying the residue when it has the desired consistence." Petrolatum Molle, U. S. P., and Petrolatum Spissum, U. S. P., are both stated to be "mixtures of hydrocarbons, chiefly of the marsh-gas series, obtained by distilling off the lighter and more volatile portions from petroleum, and purifying the residue when it has the desired melting point." They are manufactured on the large scale under the trade names of vaseline, cosmoline, etc., by the filtration of oil residuums through heated bone-black. The liquid petrolatum is a colorless or more or less yellowish, oily, transparent liquid, without odor or taste. It has a sp. gr. of 0.875 to 0.945 at 15° C.; the soft petrolatum, on the other hand, is a fat-like mass of about the consistence of an ointment, varying from white to yellowish or yellow, more or less fluorescent when yellow, especially after being melted, completely amorphous, and without odor or taste; and the hard petrolatum is a fat-like mass of about the consistency of a cerate, and in color like the softer variety. The melting point of the soft petrolatum is from 40° to 45° C., and of the hard variety from 45° to 51° C. All these varieties are insoluble in water, scarcely soluble in cold or hot alcohol, or in cold absolute alcohol, but soluble in boiling absolute alcohol, and readily soluble in ether, chloroform, carbon disulphide, oil of turpentine, benzine, benzene, and fixed or volatile oils. Paraffinum Durum, B. P., is the solid commercial paraffine or paraffine wax, as it is often called. This is a white, waxy, inodorous, tasteless substance, of sp. gr. o.877, melting (according to its source, whether from petroleum, coal, or ozokerite) between 43° and 65° C. 4. Technically Important Products.-The most important industry based upon the utilization of the hydrocarbons of this series is the refining of petroleum, which, as before stated, is a naturally occurring hydrocarbon mixture. In the United States the most important deposits of petroleum are those of Western Pennsylvania. These oil-fields extend into New York State and into Western Virginia and Ohio. In the latter State (as well as in the province of Ontario, Canada) occurs also a petroleum deposit of somewhat different character, viz., a sulphur-containing oil, which presents greater difficulties in refining. Petroleum is also found in Kentucky, Colorado, and California, but of a heavier and thicker kind. The most important foreign production is that of Baku, on the Caspian Sea, where enormous quantities of petroleum are obtained. Chemically it differs, however, from the Pennsylvania oil in containing a distinct series of hydrocarbons, the so-called "naphthenes" (see Aromatic Hydrocarbons). The refining of petroleum consists first in submitting it to a fractional distillation, the products of which are benzine, naphtha, burning oils, and residuum. The latter is then distilled at a higher temperature in separate stills, and yields paraffin oils and a coke or petroleum pitch. All the fractions require a treatment with sulphuric acid, followed by washing and treatment with alkali to remove impurities and products of destructive distillation, which impair their color and burning qualities. The paraffine oils are then chilled by artificial means and paraffine scale separated out from the heavy oils, which then are known as lubricating oils. The paraffine scale when purified by melting, pressing, and filtration yields the white paraffine wax. The most important test to be applied to a burning oil is the "fire test," which determines the temperature to which it may be heated without liberating vapors which mixing with air may produce an explosive mixture. The lowest legal test in any of the States is 110° F., and in many it is placed at 150° F. II. THE UNSATURATED HYDROCARBONS OF THE OLEFINE SERIES. Associated with the paraffin series or saturated hydrocarbons in petroleum, and capable of being formed in most cases of destructive distillation, is a series of hydrocarbons each member of which contains two hydrogen atoms less than the corresponding member of the saturated series. They possess the general formula C.H2u. The first member of the series, CH,, is apparently incapable of existing in the free state, although derivatives of it are known. The second hydrocarbon, CH, known as ethylene, the third, CH, known as propylene, and the succeeding ones as high as C30H80, are, however, obtainable. The explanation generally accepted by chemists for their molecular structure is that in them two carbon atoms are temporarily doubly linked, but that, as 60' this double linking is unstable, they act as unsaturated compounds, and readily unite with halogens and atomic groups to form saturated compounds. Thus we have for ethylene H-C-H pactly, CH, CH, and CH=CH-CH,. Their most characteristic reaction is the direct combination with two atoms of the halogens to form addition compounds, while the saturated hydrocarbons of the paraffin series can only form substitution compounds. Thus, C2H, + Cl2 = C,H,Cl. They have been named by adding the termination ene to the name of the monad radical derived from the corresponding saturated hydrocarbon. Thus, we have Methylene, CH,,(?) Ethylene, CH4) Propylene, CH ̧› Butylene, CgHg, Amylene, CH10' Hexylene, CH12. In their physical properties they resemble the methane homologues closely, the first three being gases, C,H10 a volatile liquid, and the higher members being solids like the paraffins. Most of the olefines are easily soluble in alcohol and ether but insoluble in water. Besides their ability to take up halogens to form addition compounds, they are characterized by a tendency to polymerize, especially in the presence of sulphuric acid or zinc chloride, and by the readiness with which they are oxidized by chromic acid or potassium permanganate. They are formed together with the paraffins by the destructive distillation of many substances, such as fats, waxes, lignite, and coal; illuminating gas consequently contains the olefines, and upon them in fact mainly depends its illuminating value. Ethylene, CH4, is present to the extent of from 5 to 6 per cent. in illuminating gas made from coal, but it is usually prepared by the action of an excess of strong sulphuric acid upon alcohol, the reaction being simply a dehydration of the alcohol: C2H2OH2O = C2H1. It is a colorless gas, which may be liquefied at o° C. by a pressure of 44 atmospheres. It is very slightly soluble in water and alcohol and burns with a luminous flame. It unites directly with an equal volume of chlorine to form ethylene dichloride, which condenses to oily drops, whence the name often given of "olefi ant" (or oil-forming) gas. It combines with two atoms of hydrogen in the presence of spongy platinum to form ethane, C2He Propylene and the several isomeric butylenes have been prepared. CH Of the amylenes, one (trimethyl-ethylene, CH H has been introduced into medicine as an anesthetic under the name of "pental." It is formed from tertiary amyl alcohol (amylene hydrate) by the action of dehydrating agents. It is a colorless, mobile, very volatile, and inflammable liquid, boiling at 37°-38° C. It is insoluble in water, but miscible in all proportions in chloroform, ether, and 90 per cent. alcohol. III. THE UNSATURATED HYDROCARBONS OF THE ACETYLENE SERIES. A third series of hydrocarbons, containing two hydrogen atoms less than the corresponding members of the olefine series and four less than the members of the paraffin series, is known under the name of the acetylene series. They have, therefore, the general formula C,Han-2 To explain their unsaturated character and their ability to take up four atoms of halogen or other atom or group, we assume the C-H or CHECH following structural formula for acetylene, They are produced in the destructive distillation of many organic compounds, such as wood and bituminous coal. Acetylene, the first member of the series, is produced in a variety of additional ways. Thus, when methane, ethane, ethylene, alcohol, ether, and aldehyde are led through tubes heated to redness, acetylene is produced with separation of hydrogen and other prod |