rOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 72p 



mable principle, or by uniting with the pure air which the calx is supposed to 

 contain. The metal, thus revived, is probably in some cases again corroded by 

 the hepatised ammonia, which communicates to it a black colour. Thus we may 

 account for the dark incrustation frequently formed on the tongue and internal 

 fauces, when venereal ulcers of the throat are washed with a solution of corrosive 

 sublimate. And hence also the dark tinge which is frequently communicated by 

 ill-conditioned ulcers to poultices made with a solution of sugar of lead. The 

 action of the hepatised ammonia likewise explains the reason why the probes are 

 frequently corroded when they are introduced into sinuous ulcers, or applied to 

 the surfaces of carious bones. To the same cause it is probably owing, that 

 polished metallic vessels are quickly tarnished, when they are exposed to the 

 effluvia of putrid animal substances. 



From the foregoing experiments it also appears, that animal hepatic air im- 

 parts to the fat of animals recently killed a green colour; that it renders the mus- 

 cular fibres soft and flaccid, and increases the tendency to putrefaction. It is 

 therefore a septic principle; and hence it is extremely probable, that the com- 

 pound of this fluid with volatile alkali, which is found in the matter discharged 

 by the open cancer, produces deleterious effects; for though the mischief in can- 

 cerous ulcers seems principally to depend on a morbid action of the vessels, 

 whence the unhealthy state of the matter discharged by such ulcers is supposed 

 to derive its origin, yet from the corrosion of the coats of the larger blood-vessels, 

 and the obstructions in the contiguous glands, there can be little doubt that this 

 matter aggravates the disease. The experiments recited above appear to prove, 

 that the hepatised ammonia is the ingredient which communicates to the can- 

 cerous matter its putrid smell, its greater thinness, and in short, all the peculiar 

 properties by which it differs from healthy pus. 



From these considerations it was inferred, that a medicine vi^hich would decom- 

 pose the hepatised ammonia, and destroy the fetor of the animal hepatic air, 

 without at the same time increasing the morbid action of the vessels, would be 

 productive of salutary effects. The nitrous acid does not destroy the fetor of 

 hepatic air, unless it be highly concentrated; and in this state it is well known 

 that it speedily corrodes animal substances. But the fetor of hepatic air quickly 

 disappears when it is mixed with the dephlogisticated marine acid, even though 

 the latter be so much diluted with water as to render it a very mild application. 

 Dr. C. has found that this acid, diluted with thrice its weight of water, gives 

 but little pain when it is applied to ulcers that are not very irritable; and in se- 

 veral cases of cancer it appeared to correct the fetor, and to produce a thicker 

 and more healthy pus. It is proper however to remark, that other cases occurred 

 in which it did not seem to be attended with the same salutary effects. Indeed 

 some cancerous ulcers are so extremely irritable, that applications which are at 



VOL. XVI. 5 A 



