CHLOROFORM. 833 



is inflamed with great difficulty but burns in the flame of a 

 candle colouring it green. The alcoholic solution of potash 

 destroys it, converting it into formiate of potash (Dumas), a 

 property which the name chloroform refers to : 



FoCl 3 and 4KO=KO, FoO 3 andSKCl. 



The density of its vapour is by experiment 4200, by calcu- 

 lation 4116: its combining measure 4 volumes. Chloroform 

 may be distilled from sulphuric acid, potassium or potash with- 

 out being sensibly altered. Exposed with chlorine to the 

 direct rays of the sun it is decomposed and converted into 

 hydrochloric acid and a particular chloride of carbon C 2 C1 4 , 

 which boils at 172.4 (7S centig.), and of which the density of 

 the vapour is 5300, and combining measure 4 volumes (Reg- 

 nault). This chloride of carbon has been looked upon as a 

 formic acid in which both the hydrogen and oxygen are replaced 

 by chlorine : 



C 2 C1 + C1 3 ; 



while the well known sesquichloride of carbon is related in the 

 same way to acetic acid : 



C 4 C1 3 + C1 3 . 



When the former chloride of carbon is made to pass in 

 vapour through a porcelain tube at a dull red heat, it is divided 

 into two new chlorides of carbon, of which the composition is 

 expressed according to M . Regnault, by CCl and CC1 3 . 



Chlorhydrate of chloride offormyl, 2C 2 HC1, HC1; one of the 

 products of the action of chlorine upon the chlorhydrate of the 

 chloride of acetyl. 



Per bromide o/formyl, bromoform, C 2 HBr 3 =FoBr 3 ; prepared 

 like the perchloride, and very analagous to it in properties ; its 

 density is 2.10. It is less volatile than the perchloride, and 

 more easily decomposed by alkalies. 



Periodide offormyl, iodoform, C 2 HI 3 FoI 3 . This is a yellow 

 volatile substance discovered by Serullas, which is often des- 

 cribed as an iodide of carbon. It is obtained on adding an 

 alcoholic solution of potash to a solution of iodine in alcohol, 

 till the last is discoloured, carefully avoiding any excess of 

 alkali. The alcohol is then expelled by gentle evaporation, and 

 the iodide of formyl is deposited in crystals, which are purified 

 from iodide of potassium by washing with pure water. This 



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