HALOGEN DERIVATIVES OF HYDROCARBONS. 477 



chloroform, and the treatment is, therefore, confined to the use of the stomach- 

 pump, to the maintenance of respiration with oxygen inhalation, and to the 

 use of strychnine hypodermically. 



Bromoform, Bromoformum, CHBr 3 (Tribrom-methane), is an 

 extremely heavy, colorless mobile liquid, with an ethereal odor, and 

 a penetrating, sweet taste, resembling chloroform, specific gravity 

 2.884 ; B. P. 148 C. It is sparingly soluble in water, soluble in 

 alcohol and ether. Its physiological action is similar to that of 

 chloroform. 



Bromoform may be obtained by gradually adding bromine to a cold solution 

 of potassium hydroxide in ethyl alcohol until the color is no longer discharged, 

 and rectifying over calcium chloride. It is also made by the action of an alkali 

 hypobromite on acetone. 



lodoform, lodoformum, CHI 3 = 390.61 (Triiodo-methane). This 

 compound is analogous in its constitution to chloroform and bromo- 

 form. It is made by heating together an aqueous solution of an alkali 

 carbonate, iodine, and alcohol until the brown color of iodine has 

 disappeared ; on cooling, iodoform is deposited in yellow scales, which 

 are well washed with water and dried between filtering paper. (For 

 an explanation of the chemical changes taking place see chloral and 

 chloroform.) 



lodoform occcurs in small, lemon-yellow, lustrous crystals, having 

 a peculiar, penetrating odor, and an unpleasant, sweetish taste ; it is 

 nearly insoluble in water and acids, soluble in alcohol, ether, fatty 

 and essential oils. It contains 96.7 per cent, of iodine. 



lodoform digested with an alcoholic solution of potassium hy- 

 droxide imparts, after acidulation with nitric acid, a blue color to 

 starch solution. (See reaction in Test 5 under Chloroform.) 



Experiment 54. Dissolve 4 grammes of crystallized sodium carbonate in 6 

 c.c. of water : add to this solution 1 c.c. of alcohol ; heat to about 70 C. (158 

 F.), and add gradually 1 gramme of iodine. A yellow crystalline deposit of 

 iodoform separates. 



Ethyl chloride, ^Jthylis chloridum, C 2 H 5 C1 = 64 (Chlor-cthane), 

 is prepared analogously to methyl chloride by the action of hydro- 

 chloric acid gas upon absolute ethyl alcohol : 



C 2 H 5 OH + HC1 = C 2 H 5 C1 + H 2 0. 

 In place of hydrochloric acid phosphorus pentachloride may be used : 



C 2 H 6 OH + PC1 5 = C 2 H 5 C1 + POC1, + HCL 



Ethyl chloride is a gas at ordinary temperature, but by pressure it 

 is converted into a colorless, mobile, very volatile liquid which boils at 



