70 VETEEINAKY TOXICOLOGY 



remembered that chromic acid and the bichromates suffer 

 reduction to the lower basic oxides in the body. 



Salts of chromium are extracted in the nitric acid process 

 from organic matter, and in the subsequent treatment green 

 chromium hydroxide separates along with the iron, and 

 may be recognised by well-known tests, which need not be 

 described here. 



IRON. 



Iron filings are stated to act as a mechanical poison 

 similar to powdered glass, but such cases are rare, if not 

 entirely absent, from our literature. Nor are there recorded 

 cases of poisoning by sulphate of iron (copperas, or green 

 vitriol). This salt is not an active irritant ; it produces 

 violent pain, vomiting, and purging in the human subject. 



Only a very small proportion of ingested iron is absorbed, 

 and it is extremely doubtful whether this salt would produce 

 death, at any ra^-s in the larger animals. It is now agreed 

 that a small proportion of a dose of an iron preparation 

 is absorbed, probably in the form of albuminate, but the 

 greater part of the material is excreted as iron sulphide in 

 the fseces. When iron albuminate or iron sodium tartrate, 

 which do not coagulate albumin, are injected, poisoning 

 results, but this is a case which does not come within the 

 range of practice. Absorption from the intestines is so 

 slight and so slow that poisoning does not arise when 

 iron is given by the mouth. A case is recorded by Wallis 

 Hoare* of death of cows by iron perchloride. The symp- 

 toms noted were dulness, loss of appetite, quick and 

 weak pulse, hurried respiration, cessation of lactation, 

 and obstinate constipation. Administration of magnesium 

 sulphate caused inky-black evacuations. On post-mortem 

 examination the fourth stomach was found to be thickened 

 and perfectly black, with some erosion of the mucous mem- 

 brane ; the intestines were slightly congested, and the 

 contents black. Analysis revealed an abnormal proportion 

 * Vet. Becord, 1893, p. 118. 



