be regarded as derived from the hydrocarbons of the marshgas series by substituting for a single atom of hydrogen the radicle hydroxyl (HO), as, for example, common alcohol.

Methyl Alcohol, CHO (Wood-Spirit).—This is one of the chief products of the dry distillation of wood. When pure it is a thin, colorless liquid, very similar in smell and taste to common alcohol. Crude wood-spirit, however, is always impure, has an offensive odor, and a nauseous, burn ing taste. It is employed in the arts for many of the purposes for which ordinary alcohol is used, especially in the manufacture of varnishes.

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517. Ethyl Alcohol, C,H,O (Common Alcohol, Spirits of Wine).-When solutions of sugar (C,,H,,O,,), or the sweet saccharine juices of plants, are acted upon by ferments, they are decomposed, with evolution of carbonic dioxide, and formation of alcohol. This substance may also be obtained from ethylene; ethylene may be prepared from acetylene (513), and thus it will be seen that it is. possible by a series of simple reactions to build up alcohol from the elements carbon, oxygen, and hydrogen. It is a colorless, mobile fluid, of 0.77 specific gravity, having a pleasant, fruity smell, and a burning taste. It is very volatile, and has a strong tendency to absorb moisture from the air or from bodies immersed in it, thus rendering it valuable as an antiseptic. It is highly combustible, burning with a pale-blue flame, and producing intense heat without smoke; it is therefore well adapted to burn in lamps for chemical use. Alcohol has great value as a solvent, as it acts upon many substances which water does not dissolve, and is easily separated from them on account of its extreme volatility. It boils at 173° F., and has never been frozen,

although at 166° it becomes viscid. In a concentrated form it is a potent poison, but, when sufficiently diluted, it acts upon the animal system as a stimulant. Taken freely in this form it produces inebriation, and is the active principle of all intoxicating liquors.

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518. Amyl Alcohol, C,H,,O (Fusel Oil).-This alcohol is produced together with ordinary alcohol in fermentation. It is a transparent, colorless liquid, of unpleasant, mouldy, spirituous odor, and burning taste, and is poisonous. It burns with a white, smoky flame, and has been used for illuminating purposes.

519. Wines are obtained from the expressed juice of the grape and other fruits. The fresh grape-juice, or must, is placed in vats in cellars, where the temperature is so low that the fermentation proceeds very slowly. Sometimes the wines are bottled before the fermentation is quite complete, and they continue to generate carbonic dioxide, which remains compressed within the liquid. If the carbonic dioxide is so abundant as to produce effervescence when uncorked, the wine is said to be "sparkling;" if otherwise, it is termed "still" wine.

520. Lager-Beer is freed from nitrogenized products by a slow and long-continued fermentation; hence it may be preserved for years without further decomposition. Before consumption it lies stored in vaults for months, from which circumstance its name is derived (lager, lair). The difference in color of malt liquors is owing to the various degrees of heat employed in malting. Ale is made from pale malt, while that used for porter is partially charred, giving it a brownish color and bitter flavor.

521. Distilled Liquors are obtained by subjecting certain fermented mixtures to distillation. Brandy is derived from the distillation of wine; rum from that of fermented molasses, and arrack from the distillation of fermented riceinfusion. Whiskey is obtained from corn, rye, and potatoes, by first converting their starch into sugar, then into spirit,

and distilling the product. Gin is produced from the distillation of the spirit of a mixture of barley and rye, and owes its peculiar flavor to juniper-berries.

522. Phenol, C.H.O.-A substance familiarly known as carbolic acid is regarded by the chemist as the alcohol of benzene :

Benzene, C.H. Phenol, C.H.OH.

The chief source of phenol is coal-tar, from which it is obtained by distillation. Pure phenol crystallizes at ordinary temperatures in long, colorless, needle-shaped prisms, which attract moisture from the air, deliquescing to an oily hydrate. The crystals melt at 35° C., and boil at 180° C., are slightly soluble in water, more freely in alcohol. They have a penetrating, smoky odor and a burning acrid taste. Phenol and its solutions have in an eminent degree the property of preserving animal substances from decay, and are on this account much employed as antiseptics and disinfectants. A considerable portion of the creosote of commerce consists of phenol. Genuine creosote is a colorless, oily liquid with a smoky odor and burning taste. It is a powerful antiseptic, and meat, steeped for a few hours in a solution of one part creosote to 100 parts water, remains sweet and will not putrefy. Crecsote is used very extensively in medicine, both inwardly and as an external application, but an overdose is a corrosive poison. Crude pyroligneous acid, on account of the creosote it contains, is used to preserve meats, to which it imparts a smoky flavor. The curing quality of the smoke of green wood is also owing to this cause. It is the vapor of creosote which renders smoke so irritating to the eyes.

523. Fats and Oils.-Most of the fixed oils, and the fats, both animal and vegetable, are compounds of glycerine, and acids of the acetic and oleic type. Thus beef and mutton fat consist mainly of stearic glyceride (stearin); olive-oil is oleic glyceride (olein); palm-oil is chiefly pal

mitic glyceride (palmitine). These glycerides, when decomposed, by heating with water yield glycerine and an acid.

Glycerine (C,H,O,).-When pure this substance is a nearly colorless, inodorous, sirupy liquid, of intensely sweet taste. It is readily soluble in water and alcohol, and is a powerful solvent and antiseptic. Of late years, it has been employed as a medicine; and, on account of its solvent power, it is also largely used as a vehicle for administering other medicines. It is extensively employed in the manufacture of cosmetics and perfumery. Glycerine is nonvolatile, and, when heated over 600° F., is decomposed, giving off among other products a peculiar acrid substance termed acroleine (C,H,O). This is the body which causes the irritating fumes of a smouldering candle-wick and of burning fats when the combustion is incomplete.

524. Nitro-glycerine, C,H,(NO),.—When a mixture of strong sulphuric and nitric acids acts on glycerine, at low temperatures, a violently explosive, oily liquid of lightyellow color is produced. This compound has a specific gravity at 15° C. of 1.6, is inodorous, but has a sweet, pungent, aromatic taste, and, placed upon the tongue, produces headache. Nitro-glycerine is exploded not by the direct application of heat, but by sudden concussion, and proper care in its preparation greatly lessens the danger accompanying its use.

§3. Saccharine Bodies.

525.-Saccharine bodies, sometimes called carbo-hydrates, constitute an important class of substances, interesting on account of their wide distribution in the vegetable world. Among these substances we have the sugars proper, grape-sugar, gum, starch, and woody fibre. These are probably related to the alcohols, though their exact composition has not in all cases been ascertained. Two

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of these compounds, grape and fruit sugar, break up into alcohol and carbonic dioxide under the influence of yeast. Dextrose, or grape-sugar, CH,,O,, is widely distributed in all ripe fruits, and may be prepared by boiling starch in dilute sulphuric acid. Isomeric with this compound is lævulose, or fruit-sugar, which occurs mixed with other varieties of sugar in the juices of ripe fruit, honey, etc. Both of these compounds belong to the group of glucoses. 526. Cane-Sugar, C,,H,,O,,, is produced chiefly from the cane, beet-root, sorghum, and the palm and maple trees; but by far the largest portion is from the sugarcane. The canes are crushed by passing them between grooved iron cylinders. The juice, when first expressed, is liable to rapid decomposition from the heat of the climate. This is prevented by the addition of a small quantity of lime, which neutralizes acids and coagulates impurities. The juice is evaporated by boiling in large, open vessels, and, when reduced to a proper consistency, is transferred to coolers, where a portion of it crystallizes, forming raw or brown sugar. On an average, a gallon of juice produces a pound of sugar.

Crude sugars are purified, or refined, by reducing them to a sirup, which is first filtered through twilled cotton, to separate mechanical impurities. The same effect is further. promoted by the use of serum of blood. To decolorize the sirup it is again filtered through a bed of coarsely-powdered bone-black or animal charcoal. It is then evaporated in vacuum-pans-the air being exhausted, so that it will boil at a lower temperature-and finally recrystallized. The drainage of the raw sugar forms molasses.

527. Properties.-Pure cane-sugar has a specific gravity of 1.6, is soluble in about one-third of its weight of cold water, forming a thick sirup, and separates from concentrated solutions in large, transparent, colorless crystals, having the shape of oblique rhombic prisms or modified forms. It melts at about 320°C., and solidifies, on cooling,