MINEEAL OR INORGANIC POISONS 63 



responds and is always present, so that reliance she aid not 

 be placed on this test alone, but with the formation of the 

 characteristic yellow crystalline lead iodide, the two re- 

 actions afford absolute evidence. The precipitation of lead 

 sulphate from the liquid got by heating organic matter 

 with nitric acid is not reliable, calcium sulphate being 

 always present, and, further, is not sufficiently delicate, 

 owing to the solubility of the sulphate in acid and in 

 ammonium salts. 



As is to be expected, the quantities found in alimentary 

 contents show very wide variation, as much as 2J per cent, 

 of red lead having been found, and, on the other hand, as 

 little as 2^jj grain per 2 ounces in well authenticated cases. 

 The detection of lead in the liver or kidneys, even in small 

 quantities, affords better medico-legal evidence, representing 

 absorbed lead, whereas medicinal doses — e.g., of lead acetate 

 — might easily be recognised in visceral contents, but not 

 in the organs. 



REFERENCES TO LEAD. 



1 Vet. Becord, 1904, p. 559. 



2 Vet. Becord, 1902, p. 14. 



3 D. Pugh, Vet. Becord, 1897, p. 383. 



■" J. H. Parker, Vet. Becord, 1896, p. 178. 



6 G. E. Nash, Vet. Becord, 1894, p. 398. 



^ A. W. Lawson, Vetermariam,, 1884, 447. 



^ Tuson, Veterinaria/n, 1865, pp. 6, 217, 423. 



* A. Broad, Veterinarian, 1865, p. 222. 



' ' Case of Lead Poisoning,' Veterinarian, 1855, p. 609 



MERCURY. 



Forms and Oecuppence. — The most important soluble 

 compound of mercury is the bichloride or corrosive svh- 

 limate, one of the most powerfully corrosive and bacteri- 

 cidal of the salts of the heavy metals. It is not often 

 the cause of accidental poisoning. The mercurous chloride 

 or calomel, being insoluble, is non-toxic — save in large 



