Properties.-Colourless liquid possessing a smell similar to that of acetic acid; b. p. 140'7°; sp. gr. 1'016 at 0°; soluble in water; the acid may be separated from its aqueous solution as an oily layer by the addition of calcium chloride. PREPARATION L. ETHYLENE DIBROMIDE, C2H4Bг2 = CH2Br.CH2Br LITERATURE.-Balard (1826), Ann. Ch. Phys. (2) 32, 375; Erlenmeyer, Bunte (1873) Ann. Ch. Pharm. 168, 64; Erlenmeyer) 1878), Ann. Ch. Pharm. 192, 244. A mixture of 25 grms. strong alcohol and 150 grms. conc. sulphuric acid are heated in a 2-litre round-bottomed flask on a sand-bath until ethylene vapour is evolved in a steady stream. A mixture of I part alcohol and 2 parts conc. sulphuric acid are run into the flask through a tap funnel at such a speed that the stream of gas continues without interruption, and at the same time without causing the contents of the vessel to froth up too violently. The gas is purified from alcohol, ether, sulphurous acid, and carbonic acid, by conducting it through a series of Woulff's bottles fitted with safety tubes and connected with the generating flask (Fig. 24). The first of these bottles (a) is empty, the second (b) contains conc. sulphuric acid, the third (c) and fourth (d) dilute caustic soda solution. Thus purified, the ethylene passes into a long bent tube (R) 1 and a Woulff's bottle (e), which contain bromine covered with a layer of water. The tube (R) contains 150 grms. bromine and I c.c. water, and the bottle (e) 50 grms. bromine and 1 c.c. water. The last bottle is filled to a height of 5 cm. with broken glass, and then with lumps of dry soda-lime. As soon as the bromine assumes a pale yellow tint by absorption of ethylene and conversion into ethylene bromide, the evolution of gas is interrupted or the liquid removed and a fresh quantity of bromine introduced. The crude ethylene bromide is shaken with dilute caustic soda solution, washed with water, separated from the aqueous layer and dehydrated over calcium chloride. After decanting from the calcium chloride it is rectified. Properties.-Colourless liquid which solidifies at o° to a crystalline mass and melts at 9°; b. p. 129′5°; sp. gr. 2'17 at 20°. 1 This may be replaced by a Woulff bottle, and cooled if necessary in cold water. PREPARATION LI. ETHYLENE ALCOHOL, C2HO2=CH2(OH).CH2(OH). (Ethylene Glycol.) 199; LITERATURE.-Wurtz (1856), Compt. rend. 43, Atkinson (1858), Phil. Mag. (4), 16, 433; Simpson (1859), Proc. Roy. Soc. 9, 725; Erlenmeyer (1874), Ann. Ch.. Pharm. 173, 117 and (1875) 177, 145 and (1878) 192, 244; Zeller, Hüfner (1874), Journ. Prakt. Ch. (2) 10, 271 and (1875) (2) 11, 229. 188 grms. ethylene bromide, One hundred and eighty-eight grms. ethylene bromide, 138 grms. potassium carbonate, and I litre water are heated to boiling in a 2-litre roundbottomed flask on the sand-bath with reflux condenser. The boiling is continued until the whole of the ethylene bromide has disappeared which occurs in about 10 hours. Carbonic acid and vinyl bromide (C,H,Br) are evolved. The latter may be collected as monobromethylene bromide by attaching to the upper part of the condenser a Liebig bulb apparatus containing bromine. When the reaction is finished, the contents of the vessel, while still warm, are poured into a porcelain basin and carefully concentrated on the water-bath until potassium bromide begins to separate out in considerable quantity. The cooled I mass is mixed into a paste with strong alcohol, and the alcoholic solution of glycol separated from potassium bromide by draining the mass at the filter-pump and washing well with strong alcohol. The alcohol is distilled off from the filtrate on a brine-bath and the residue on the oil-bath. The portion boiling at 185-205° is separately collected and re-distilled. C2H ̧Bг2 + K2CO3 + H2O = C2H(OH)2 + 2KBr + CO2 Ethylene Bromide Ethylene Glycol. C2HBг2 + K2CO3 = C2H ̧Br + KBr + KHCO3 Vinyl Bromide. C2H ̧Br + 2Br = C2H3Br Bromethylene Bromide. Properties.-Syrupy liquid; b. p. 197 ̊5°; sp. gr. 1*125 at 0°; soluble in water and alcohol. PREPARATION LII. ETHYLENE CHLORHYDRIN, C2H¿CIO= (Ethylene Chlorhydrate) Literature.-Wurtz (1859), Ann. Ch. Phys. (3) 55, 400; Carius (1862), Ann. Ch. Pharm. 122, 73 and (1862) 124, 257; Fittig, Chanlaroff (1884), Ann. Ch. Pharm. 226, 326. 100 grms. glycol. 1 Preparation of Chloride of Sulphur.-One hundred grms. sulphur are melted over a small flame in a dry retort of about |