4i 8 Dr. Crawford’s Experiments on the Matter 
powders which were formed by the aaion of the hepatic air 
upon the furface of the mercury, and found them to be aethiops 
mineral, and cinnabar. 
Of the air extricated from animal fubftances by putrefaction. 
In the beginning of July, 1789, about two ounces of veal, 
{lightly putrid, was introduced into a large phial, which was 
filled with diftilled water, and inverted over a quantity of 
the fame fluid. At the end of three days a few bubbles of air 
had appeared at the bottom of the phial; the water had ac- 
quired a light brown colour, and emitted a fetid fmell. At the 
expiration of feven days we could perceive that the quantity of 
air at the bottom of the phial was manifeftly increafed, al- 
though its progrefs was very flow. The water, by the diflolutioii 
of a part of the veal, had now acquired the confidence of a 
thin mucus, its brown colour was fomewhat deepened, and it 
emitted a highly fetid fmell. A little nitrated filver being 
dropped into a portion of this water, previoufly filtered, a daik 
brown precipitate was immediately produced. Lime-water, 
mixed with another portion of it, occasioned an afh-coloured 
precipitate ; and when concentrated nitrous acid was added to a 
third portion, the fetid fmell was deftroyed, a flight efier- 
vefcence took place, and a yellow flaky matter was difengaged. 
At the end of feven weeks, a quantity of air, amounting to 
two and one-fixth dram meafures was collected in the phial. 
This air had a fetid odour. Being agitated with water, fix- 
tenths of it was abforbed. The refidue extinguifhed flame. 
I next examined the air extricated from veal which was fuf- 
fered to putrefy over mercury. 
Oa 
