298 Dr. Crawford’s Experiments on the Matter 
tion depofits a reddifti brown precipitate upon the addition of 
nitrated filver. Whence it follows, that the cancerous matter 
contains a principle which has many of the properties of he- 
patic air, and which may perhaps not improperly be termed 
animal hepatic air. 
It has moreover been (hewn, that the matter of cancer is 
impregnated with an alkali which is in fuch a (fate as to change 
the colour of vegetable tinftures. I had very little doubt that 
this was the volatile alkali : for it is well known, that putrid 
animal fubftances frequently abound with that fait ; but have 
never, I believe, been found to contain a fixed alkali in a dif- 
engaged date. With a view, however, more decifively to 
determine this point, I tried the following experiment. A 
quantity of cancerous matter, diffufed through diftilled water, 
was introduced into a glafs retort to which a receiver was 
adapted. The mixture was (lowly diftilled by means of a fand 
heat ; and a fmall quantity of the liquor which came over into 
the receiver being poured into an infufion of Brazil wood, in- 
ftantly imparted to it a deep red colour. 
Hence it clearly appears, that the alkali contained in the 
cancerous matter was the volatile, becaufe it was feparated by 
diftillation with a heat which did not exceed that of boiling 
water. 
It feemed extremely probable, that the above-mentioned 
alkali was united to the aerial fluid with which the matter of 
cancer is impregnated. Of the truth of this fa£t I was per- 
fuaded by dbferving, that the fmell of the cancerous matter 
was greatly iucreafed by the addition of the vitriolic acid : for 
I could fcarcely avoid concluding, that this phenomenon arofe 
from an union between the acid and alkali, in confequence of 
which the odoriferous principle was extricated by a fuperior 
attra&ion. 
