HALOGEN DERIVATIVES OF HYDROCARBONS. 475 



on alcohol. The three substances named, after being mixed with a 

 considerable quantity of water, are heated in a retort until distilla 

 tion commences ; the crude product of distillation is an impure chloro- 

 form, which is purified by mixing it with strong sulphuric acid and 

 allowing the mixture to stand ; the upper layer of chloroform is 

 removed and treated with sodium carbonate (to remove any acids) 

 and distilled over calcium chloride (to remove water). 



A full explanation of the formation of chloroform by the above process will 

 be given later on in connection with the consideration of chloral, where it will 

 be shown that alcohol is converted by the action of chlorine first into aldehyde 

 and subsequently into chloral, which, upon being treated with alkalies, is 

 decomposed into an alkali formate and chloroform. 



The action of the chlorine of the calcium hypochlorite (which is the active 

 principle in bleaching-powder) upon the alcohol is similar to that of free 

 chlorine upon alcohol; in both cases aldehyde, and afterward chloral, are 

 formed, which latter, in the manufacture of chloroform, is decomposed by the 

 calcium hydroxide into chloroform and calcium formate. The last-named salt 

 is, however, not found in the residue of the distillation, because it is decomposed 

 by bleaching-powder and calcium hydroxide into calcium carbonate, chloride, 

 and water : 



Ca(CHO 2 ) 2 + Ca(ClO) 2 + Ca(OH) 3 = 2CaCO 3 + CaCl 2 + 2H 2 O. 



If the various intermediate steps of the decomposition are not considered, the 

 process may be represented by the following equation : 



4C 2 H 6 + 8Ca(C10) 2 = 2CHC1 3 -f 3[Ca(CHO 2 ) 2 ] + 5CaCl 2 + 8H 2 O. 

 Alcohol. Calcium Chloroform. Calcium Calcium Water, 



hypochlorite. formate. chloride. 



Chloroform is now made extensively by the action of bleaching-powder upon 

 acetone ; the reaction takes place thus : 



2CO(CH 3 ) 2 -f 3Ca(C10) 2 = 2CHC1 3 + 2Ca(OH) 2 + Ca(C 2 H 3 <V 2 

 Acetone. Calcium Chloroform. Calcium Calcium 



hypochlorite. hydroxide. acetate. 



Pure chloroform is a heavy, colorless liquid, of a characteristic 

 ethereal odor, a burning, sweet taste, and a neutral reaction ; it is but 

 very sparingly soluble in water, but miscible with alcohol and ether 

 in all proportions ; the specific gravity of pure chloroform is 1.50, 

 but a small quantity of alcohol (from one-half to one per cent.), 

 allowed to be present by the U. S. P., causes the specific gravity to 

 be about 1.48; boiling-point 61 C. (141.8 F.), but rapid evapora- 

 tion takes place at all temperatures. 



Chloroform or its vapors do not ignite readily, but at a high tem- 

 perature chloroform burns with a green flame. When kept in a 

 partially filled bottle exposed to daylight it decomposes with the for- 

 mation of the highly irritating carbonyl chloride : 



