54 Dr. J. Sten house oti Chloropicrine. 



less, the whole of the nitropicric acid has been decomposed ; 

 but if the solution retains a yellow colour, this indicates that 

 it still contains undecomposed nitropicric acid ; and on the 

 addition of a fresh quantity of hypochlorite of lime, more 

 chloropicrine is obtained. When nitropicric acid is boiled 

 with a filtered solution of hypochlorite of lime, the oil is gene- 

 rated in the way already described, and it becomes apparent 

 that a quantity of carbonate of lime is precipitated at the same 

 time; and as the residue in the retort is found to contain not 

 a trace of organic matter, carbonic acid, muriatic acid, and 

 chloropicrine appear to be the only products of this decom- 

 position. The oil which had passed into the receiver was 

 separated from the acid liquid which surrounded it, and was 

 repeatedly washed with water containing a little carbonate of 

 magnesia. It was then deprived of any adhering moisture by 

 being allowed to stand for some days over fused chloride of 

 calcium. On being transferred into a small retort, it was 

 cautiously rectified on the sand-bath, when pure chloropicrine 

 distilled over as a colourless neutral oil possessing a very con- 

 siderable refractive power. 



When nitropicric acid is boiled with a mixture of chlorate 

 of potassa and muriatic acid, it is converted into chloranile, 

 which chiefly remains in the retort, and into chloropicrine, 

 which passes into the receiver. The chloropicrine obtained 

 by this process is always impure, and contains some crystals 

 of chloranile which have been carried over into the receiver 

 along with the oil and watery vapours : but from these the 

 chloropicrine may be easily purified by careful rectification 

 with water. 



When nitropicric acid is boiled with aqua regia, it is also 

 resolved into chloropicrine and chloranile; but the quantity 

 of the oil is much larger, and that of the chloranile much 

 smaller than when chlorate of potash and muriatic acid are 

 employed. The same products, viz. chloropicrine and chlo- 

 ranile, are also formed when a stream of chlorine gas is sent 

 through a hot aqueous solution of nitropicric acid. The ni- 

 tropicric acid is but slowly acted on by the chlorine, and three 

 or four days' treatment with chlorine is required to effect its 

 complete decomposition. Chloropicrine is also generated 

 when chaibazotate of potash is heated with a solution of hy- 

 pochlorite of lime. Chloranile cannot be converted into chlo- 

 ropicrine by being boiled either with nitric acid, aqua regia, 

 or hypochlorite of lime. 



The nitropicric acid which I employed for these experi- 

 ments was prepared partly from indigo, but by far the larger 

 portion of it from the yellow gum-resin of Botany Bay. This 



