d. Chloroform readily reduces the hot potassio cupric solution (distinction from chloroethylidene and from alcohol).

e. Chloroform may be separated from slight mixtures of Ether, Alcohol, water, etc., as follows: To 10 parts of the impure chloroform, add 2 parts of concentrated sulphuric acid, and shake together occasionally for 24 hours. Remove the upper layer, add to it part of (crystallized) carbonate of sodium previously dissolved in 1 part of water, agitate and digest (cold) for half an hour, then remove the lower layer and distil it from part of freshly-burned lime.-Distillation from dry calcium chloride separates chloroform from alcohol.-To separate from Ethereal Oil (ethyl and ethylene sulphates), distil from animal charcoal.

198. CHLORAL HYDRATE. CHCI,O.H2O. Characterized by its sensible and physical properties (a), and its formation of chloroform (b), and of chloralide (c). It has, with alkalies, considerable reducing power (d). Separated from chloral alcoholate by its slight solubility in cold chloroform and its greater solubility in cold water.-Estimated from the amount of chloroform it produces (e).

a. A friable solid, crystallizing from solvents in transparent rhomboidal crystals, or congealing in a white crystalline mass, melting at about 60° C. (140° F.) and boiling at 95° C. (203° F.) -(the Alcoholate boils at 116° C.). It slowly sublimes, in the bottle, at ordinary temperatures. It is neutral in reaction, and of an aromatic, penetrating, and slightly acrid odor, and bitter, caustic taste. Melted in a spoon, over the flame, it does not take fire (distinction from the alcoholate). It is slightly deliquescent, readily soluble in 1 parts of water (the alcoholate dissolves sparingly in cold water); soluble in alcohol, ether, benzole, petroleum naphtha, bisulphide of carbon; slightly soluble in cold chloroform (the alcoholate freely soluble). It forms liquid mixtures with camphor, and with phenic acid, and a crystalline mixture with glycerin.

b. Fixed and volatile alkalies, and their carbonates, in solution, decompose chloral hydrate-the chloroform subsiding from the milky mixture.

C ̧¤¤1 ̧O.¤ ̧0+KHO=CHC1,+KCHO,+¤‚0

(100 parts chloral hydrate producing 72.2 parts of chloroform.) (Trichloracetic acid, also decomposed by alkalies into chloroform and formate, has an acid reaction, and boils at 195° C.)

c. Concentrated sulphuric acid separates, from about an equal weight of chloral hydrate, anhydrous chloral-the latter rising to the surface, as a pungent and irritating oily liquid, of spec. grav. 1.5.-Chloralide is formed when chloral hydrate (concentrated, if necessary, by distillation from chloride of calcium) is heated with about six times its volume of concentrated sulphuric acid, at 125° C., for some time. When cool, the mixture is diluted with six measures of water, and, if carbonized at all, extracted with ether. On evaporating the ether the chloralide (C,H,C,O,) crystallizes in stellate groups of prisms (or in needles) which melt at 116° C. and burn at 200° C. with a green-edged flame.-In certain conditions, sulphuric acid changes chloral into metachloral (insoluble in water, alcohol, or ether).

d. Chloral hydrate, in the act of decomposition by ammonia, promptly reduces nitrate of silver as a specular coating.Aqueous solution of pure chloral hydrate does not within a few minutes perceptibly decolorize the permanganate of potassium solution, and does not at all affect argentic nitrate.-The potassio cupric solution is reduced by chloral according to 197, d.

Quantitative.—e. Take 10 grams of the chloral hydrate, dissolve in the least quantity of water, and add, in a graduated tube holding 20 c.c., ammonia enough to be a slight excess for the absolute chloral hydrate taken, according to the equation in b (5 c.c. of water of ammonia of spec. grav. 0.90). Stopper tightly in the tube, which should be nearly filled by the liquid, and leave until the subsident layer no longer increases-four to twelve

of potassa (distinction from Glucose). Lime forms a soluble compound with sucrose.-Concentrated sulphuric acid blackens sucrose on warming, with separation of carbon and evolution of sulphurous and formic acids (distinction from Glucose).—Dilute minreal acids (2 to 3 per cent.), boiled 10 to 15 minutes with sucrose, transform it into glucose. The same change is very slowly effected by long boiling in water, and with moderate rapidity by boiling with dilute vegetable acids. Also by the conditions of alcoholic fermentation.

d. Ammoniacal solution of acetate of lead gives a white precipitate (Pb,C,,H,,O,,), scarcely soluble in cold but readily soluble in hot water.

e. The blue to violet and rose-red precipitate made by adding potassa to nitrate of cobalt solution and boiling is scarcely altered by presence of sucrose, or held a little more in the violet. (In presence of Glucose, the mixture after boiling is colorless or brownish, but not violet or blue.)

CARAMEL. A mixture of three compounds:

Caramelane-brittle at ordinary temperatures, soft at 100° C.,

odorless and bitter; deliquescent and very soluble in water, sparingly soluble in alcohol, insoluble in ether. Caramelene-brittle, freely soluble in water, not deliquescent, sparingly soluble in alcohol, insoluble in ether.

Caramelin-black, shining, and infusible; having three modifications with different and varying solubilities.

Caramel is precipitated by subacetate of lead solution; and reduces potassio cupric solution. As generally prepared, caramel has a characteristic, "burned-sugar" odor.

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190. MANNITE. C.H,,O,. Crystallizes readily from solution in thin, four-sided prisms; melts at 160° C., and at 200° C. (392° F.) distils with little decomposition. It dissolves in 6 or 8 parts of water of ordinary temperature, in 80 parts of 60 per cent, alcohol or 1400 parts of absolute alcohol or smaller quantities of boiling alcohol, but is insoluble in ether.—It is not black

ened by concentrated sulphuric acid, or turned brown by boiling with potassa, and it does not reduce the potassio cupric sulphate solution. It is not subject to the alcoholic fermentation.

ALCOHOLS AND THEIR PRODUCTS.

191. METHYLIC ALCOHOL. CHO. Recognized by its sensible and physical properties (a); its reaction with potassa and, as a commercial article, with sulphuric acid (b); by solution of recent mercuric oxide (c); by its reducing power (d), and its formation of formic acid (e). It is separated by fractional distillation (f). It is approximately determined as methyl oxalate (g) or as formic acid (e, and Formic acid j or k).

a. Pure methylic alcohol is a colorless liquid, of spec. grav. 0.800, boiling at 66° C. (151° F.), and of characteristic taste and odor. The commercial article is seldom free from empyreuma. It is miscible in all proportions of water, alcohol, and ether, and dissolves resins and nearly all substances soluble in ethylic alcohol.

b. The addition of potassa, with boiling by the heat of the water-bath, causes a brown color in a short time (Ethylic alcohol only after a long time).-Ordinary methylic alcohol gives a red to red-brown color with concentrated sulphuric acid.

c. Add (to the distillate ƒ) 2 or 3 drops of very dilute solution of mercuric chloride, then solution of potassa in excess, agitate and warm. If methylic alcohol is present, the mercuric oxide will be dissolved.

d. Methylic alcohol readily decolorizes permanganate of potassium solution; but does not reduce silver nitrate, or potassio cupric solution.

e. Oxidation to formic acid is effected by distillation of 2