QO Dr . Crawford’s Experiments on the Matter 
cate d This aerial fluid was mixed with a yellow empyreu- 
matic oil. A portion of it being agitated with water was 
found to be pertly imbibed by that fluid , and nitrated fnver, 
dropped into the water thus impregnated, produced a reddilh 
precipitate, _ 
One meafure of the air, obtained in the foregoing expert- 
ment, being mixed over mercury with an equal bulk or alka- 
line air, the volume of the mixture was found gradually to 
decreafe ; and, at the end of three hours, the a.r in the tube 
occupied the fpace of only one meafure and two tenths. An 
oily depofit was now made upon the inner furface of the u e. 
At the expiration of eight days, the interior furface of the 
tube was covered with flender films, which had a yellowilh 
4paft, and which were irregularly fpread upon it. e upper 
furface of the mercury within the tube was corroded ; in iome 
places it had a reddilh burnilhed appearance ; m others, it was 
changed into an alh-coloured powder, interlperfed with brown 
foots. The tube was now removed from the mercury and 
the air that remained in it had a llrong fetid fmell, refembhng 
that of burned bones. 
' It has been already obferved, that before the water was «>■ 
tirely 'evaporated, the vapour had loft the odour of the can- 
cerous matter, and had acquired that of animal fubftances 
recently boiled. Hence it appears, that the matter upon which 
the peculiar fmell of cancerous ulcers depends, is a very vo a 
' tile fubftance, for it efcaped at the beginning of the pro«&| 
It alfo appears, that this volatile fubftance, which is probably 
the aftive principle in the matter of cancer, is not changed, y 
limule expofure to heat, into a permanently elaftic fluid , 
the air that efcaped at the beginning of the procefs, although 
it fuelled ftrongly of the cancerous matter, was foun J 
I 
