119 



is made to react on excess of pyromeconic acid. These crystals are 

 slightly soluble in water, but readily so in boiling alcohol, they red- 

 den litmus faintly, and impart to persalts of iron a deep purple co- 

 lour, quite distinct from the red produced by the original acid. Nitrate 

 of silver causes no precipitate in solutions of this acid ; neither when 

 boiled does it reduce the oxide to the metallic state. Submitted to 

 destructive distillation it fuses, and then blackens ; hydrobromic acid 

 is evolved in large quantity ; and after some time a white crystalline 

 sublimate makes its appearance, but in quantity too small to admit 

 of examination. 



Bromopyromeconate of lead, Pb C^^ Hg Br. Og + H 0, is pre- 

 cipitated as small dense crystalline grains, when warm alcoholic solu- 

 tions of the acid and acetate of lead are mixed together. 



2. On the Organs in which Lead accumulates in the Horse, 

 in cases of slow poisoning by that Metal. By Dr 

 George Wilson. 



The chief object of this paper was to state the result of a careful 

 analysis of the viscera of a mare, which had died after receiving 

 daily, for six weeks or more, carbonate of lead in its food and drink. 

 Portions of the lungs, the heart, the large intestine and its contents, 

 the stomach and duodenum, the spleen, the kidney, and the liver, 

 were subjected to analysis by the author, assisted by Mr Stevenson 

 Macadam. 



As the quantity of animal matter was large, it became a question 

 what preliminary process should be followed, with a view to facili- 

 tate the final charring to which each organ must be subjected. Sul- 

 phuric acid was rejected on account of its liability to contain lead, 

 and the certainty of its forming an insoluble compound with the 

 lead it mio^ht encounter in the tissues. Nitric acid had been found 

 in previous trials to act too slowly ; and a mixture of chlorate of 

 potass and hydrochloric acid left too large a residue of saline matter, 

 to seem applicable. Aqua regia, accordingly, which has been re- 

 commended in such cases by the French chemists, was tried, and was 

 found to answer every expectation. 



Each of the organs was digested in a mixture of one part of nitric 

 acid and two of hydrochloric acid, which dissolved everything but 

 the fat. The resulting solution was evaporated to dryness, the resi- 



