420 
Dr. Crawford’s Experiments on the Matter 
Of the effects produced ly expofing frefi animal fubjlances to 
atmofpherical, hepatic , and pure air. 
Two tubes, of nearly the fame fize, were inverted over 
mercury. Into one of thefe was introduced common air, and 
into the other an equal bulk of hepatic air, obtained from liver 
of fulphur by the vitriolic acid. Equal quantities of frefli 
veal, confiding of a mixture of mufcular fibres and of fat, 
and weighing each one dram, were then expoled to thefe airs. 
At the end of three days the piece that was in contact with the 
common air had not altered its colour or confidence, but 
fmelled a little putrid. The colour of the fatty parts of the 
piece that was expofed to the hepatic air was changed to a dark 
green, the mufcular fibres were cracked and fhrivelled on the 
furface as if they had been feared with a hot iron, and the 
whole had acquired a foft confidence. 
Similar trials were made with two pieces of frefh veal, one 
of which was expofed' over mercury to common air, and the 
other to air extricated from putrid veal by didillation. The 
former in three days had not changed its appearance ; the latter 
had become green round the edges, and was interfperfed with 
green fpots. The furface of the mercury in the jar which 
contained the lad had acquired a brown colour ; whereas that 
of the mercury in the jar which contained the common air was 
clear and bright. The pieces of veal were differed to remain 
in this fituation for fix weeks. After a few days had expired, 
that which was expofed to the animal air did not appear to 
differ any farther change. Its colour, which in the courfe of 
a week had become brown, continued unaltered, and no difio- 
iution took place. The air at the lad was very fetid ; it occar 
fioned 
