546 POISONS : THEIR EFFECTS AND DETECTION. [§ 724 . 
The external application of oxalic acid does not appear to cause 
illness ; workmen engaged in trades requiring the constant use of the 
acid often have the nails white, opaque, and brittle ; but no direct injury 
to health is on record. 
A large dose of either causes a local and a remote effect; the local is 
very similar to that already described as belonging to the mineral acids, 
i.e. more or less destructive of the mucous membranes with which the 
acid comes in contact. The remote effects may only be developed after 
a little ; they consist essentially of a profound influence on the nervous 
system. Though more than 1000 cases of oxalic acid poisoning have 
occurred since Christison wrote his treatise, his graphic description still 
holds good. “ If,” says he, “ a person immediately after swallowing a 
solution of a crystalline salt, which tasted purely and strongly acid, is 
attacked with burning in the throat, then with a burning in the stomach, 
vomiting, particularly of bloody matter, imperceptible pulse, and 
excessive languor, and dies in half an hour, or still more, in twenty, 
fifteen, or ten minutes, I do not know any fallacy which can interfere 
with the conclusion that oxalic acid was the cause of death. No parallel 
disease begins so abruptly, and terminates so soon ; and no other 
crystalline poison has the same effect.” The local action is that of a 
solvent on the mucous tissues. If from 10 to 30 grms. are swallowed, 
dissolved in water, there is an immediate sour taste, pain, burning in 
the stomach, and vomiting. The vomit may be colourless, greenish, or 
black, and very acid; but there is a considerable variety in the 
symptoms. The variations may be partly explained by saying that, in 
one class of cases, the remote or true toxic effects of the poison pre¬ 
dominate ; in a second, the local and the nervous are equally divided ; 
while in a third, the local effects seem alone to give rise to symptoms. 
In a case at Guy’s Hospital, in 1842, there was no pain, but vomiting 
and collapse. In another case which occurred in 1870, a male (aged 48) 
took 10-4 grms. (162 grains) ; he had threatening collapse, cold sweats, 
white and red patches on the tongue and pharynx, difficulty in swallow¬ 
ing, and contracted pupils. Blood was effused from the mouth and anus ; 
on the following day there were convulsions, coma, and death thirty-six 
hours after taking the poison. In another case, there were rapid loss of 
consciousness and coma, followed by death in five hours. Death may be 
very rapid ; e.g., in one case {Med. Tunes and Gaz., 1868) it took place 
in ten minutes ; there was bleeding from the stomach, which doubtless 
accelerated the fatal result. Orfila has recorded a death almost as rapid 
from the acid oxalate of potash ; a woman took 15 grms. ; there was no 
vomiting, but she suffered from fearful cramps, and death ensued in 
fifteen minutes. In another case, also recorded by Orfila, there was 
marked slowing of the pulse, and soporific tendencies. With both oxalic 
acid and the acid oxalate of potash, certain nervous and other sequelae 
