OEGANIC POISONS AND DEUGS 133 



shaped crystals, in which the same salt is so generally 

 observed in urinary deposits of the herbivorous animals. 



Oxalic acid is used on a fairly large scale commercially as 

 a straw-cleaning agent, and under the name of salts of 

 sorrel or salts of lemon, oxalic acid is used for domestic 

 purposes, such as the cleaning of straw hats and brass- 

 work, and the removal of ink stains. It resembles Epsom 

 salt, and confusion with it has caused accidents. Oxalic 

 acid is a common poison in the human subject, but cases of 

 the poisoning of large animals by it are very unusual. 

 Dogs may, however, be poisoned accidentally by this agent 

 in doses of about 15 grains, and cats by about 3 grains. 



Symptoms. — Concentrated oxalic acid causes, in dogs, 

 nausea and vomiting of black or brown acid material, 

 DiflBculty in swallowing, thirst, diarrhoea, and colic are 

 alimentary symptoms common to irritant poisoning. 

 Gamgee * indicates labouring and spasmodic respiration, 

 injection of conjunctivae, and dilataj;ion of pupil ; small and 

 irregular pulse ; and with advancing stupor and prostration 

 tetanic twitchings of the muscles. 



Oxalic acid and oxalates are absorbed slowly and excreted 

 by the kidneys as calciuhi oxalate, which, being insoluble, 

 may cause calculi. 



Post-Mortem Appearances. — These are — a blanched 

 appearance of the membranes of the mouth, fauces and 

 gullet. The stomach contains much gelatinous mucus, and 

 is rarely perforated. More or less intestinal inflammation 

 is observed, and the blood is dark and fluid. It will be 

 remembered that oxalates prevent the coagulation of blood 

 by removing the soluble lime in the form of calcium 

 oxalate. 



Treatment. — Burnt magnesia or chalk are better than 

 carbonate of potash or soda, since the former render 

 oxalic acid insoluble. Lime water and oil and demulcents 

 are valuable, with stimulants as indicated. 



Chemical Diagnosis. — Oxalic acid may be extracted from 

 organic matters by feebly acidified water, but the best 

 * ' Veterinarian's Vade-Mecum,' 1868, p. 137. 



