An Experimental Inquiry on Poisoning by Oxalic Acid - 1823

Dr Robert Christison experimented on dogs by giving them 50 grams of pure oxalic acid, which generally causes vomiting, so in order to observe what happens, he sutured the stomach to prevent vomiting. 

He makes observations at different minute marks below:

2’ He began to make violent efforts to vomit, which were frequently repeated, till
12’, when they ceased; and the breathing became full and frequent; sensibility unimpaired; great restlessness,
16’ 30”. Breathing short, and at times suspended for a few seconds; he then hung the head in a peculiar manner, looked very dull, lay down on the side, and would not rise when stirred; at last, when he was set on his legs, he walked easily across the room; suddenly the breathing became very quick and short, and then ceased, although the chest was quite relaxed ; he staggered a few paces, and sank down on the side at
20’, motionless and senseless; the body was now spasmodically extended for a second or two, after which he made a few convulsive gasps; no pulsation could be felt in the region of the heart after the 20th minute.
21’. Death being complete, the body was opened without delay. The heart was distended in its pulmonary cavities, and not contractile; the blood in those cavities was dark, in the aortal florid, in both fluid, and coagulated almost immediately in loose clots.

There are 15 pages of further experiments recorded.