544 poisons : their effects and detection. [§ 722. 
century, a little more than fifty years after its discovery. Thompson 1 
was the first who attempted, by experiment on animal life, to elucidate 
the action of the poison ; he noted the caustic action on the stomach, 
and the effects on the heart and nervous system, which he attributed 
simply to the local injury through the sympathetic nerves. Orfila 2 
was the next who took the matter up, and he made several experiments ; 
but it was Robert Christison 3 who distinctly recognised the important 
fact that oxalic acid was toxic, quite apart from any local effects, and 
that the soluble oxalates, such as sodic and potassic oxalates, were 
violent poisons. 
§ 722. Robert and Kiissner 4 have made some extended researches 
on the effects of sodic oxalate on rabbits, cats, dogs, guinea-pigs, hedge¬ 
hogs, frogs, etc., the chief results of which are as follows. On in¬ 
jection of sodic oxalate solution in moderate doses into the circula¬ 
tion, the heart’s action, and therefore the pulse, become arhythmic ; 
and a dicrotic or tricrotic condition of the pulse may last even half a 
day, while at the same time the frequency may be uninfluenced. The 
blood-pressure also with moderate doses is normal, and with small 
atoxic doses there is no slowing of the respiration. On the other hand, 
toxic doses paralyse the respiratory apparatus, and the animal dies 
asphyxiated. With chronic and subacute poisoning the respiration 
becomes slower and slower, and then ceases from paralysis of the 
respiratory muscles. The first sign of poisoning, whether acute or 
chronic, is a sleepy condition ; dogs lie quiet, making now and then 
a noise as if dreaming, mechanical irritations are responded to with 
dulness. The hind extremities become weak, and then the fore. This 
paresis of the hind extremities, deepening into complete paralysis, 
was very constant and striking. Take, for example {op. cit.), the 
experiment in which a large cat received in six days five subcutane¬ 
ous injections of 5 c.c. of a solution of sodic oxalate (strength 1 : 30), 
equalling -16 grm. ; the cat died, as it were, gradually from behind 
forwards,, so that on the sixth day the hinder extremities were fully 
motionless and without feeling. The heart beat strongly. The tem¬ 
perature of the poisoned animal always sinks below normal. Convulsions 
in acute poisoning-are common, in chronic quite absent ; when present 
in acute poisoning, they are tetanic or strychnic-like. In all the ex¬ 
periments of Robert and Riissner, lethal doses of soluble oxalates 
caused the appearance of sugar in the urine. 
J. Uppmain 5 made forty-nine experiments on dogs, in which he 
administered relatively large doses by the stomach ; no poisonous effect 
1 Lond. Med. Rejp., iii. 382. 2 Traite de Toxicologie. 
3 Edin. Med. and Surg. Journ., 1823. 
4 “ Exper. Wirkungen der Oxalsaure,” Virchow’s Archiv, lxxvii. 209. 
5 Allg. Med. Central Ztg., 1877. 
