728 PHILOSOPHICAL TRANSACTIONS. [aNNO 1790. 



phlogisticated air, the inflammable principle in the state of heavy and of light 

 inflammable air, and a substance which, by means of heat or of putrefaction, is 

 capable of being converted into animal hepatic air. When the muscular fibre, 

 after the death of the animal, is exposed to the pure air of the atmosphere; the 

 latter, by a superior attraction, combining with the heavy inflammable air, pro- 

 duces fixed air, and at the same time furnishes the quantity of heat necessary to 

 the formation of animal hepatic air. The cohesion of the fibre being thus de- 

 stroyed, the fixed, as well as the light inflammable and phlogisticated air, which 

 enter into its composition, are disengaged, and the 2 latter fluids, uniting with 

 each other, produce the volatile alkali. The alterations which take place in pu- 

 trefaction are in most respects similar to those which arise from destructive distil- 

 lation. By exposure to heat the fixed air of the animal fibre is extricated, he- 

 patic air and volatile alkali are produced, and the inflammable principle, not 

 coming into contact with the pure air of the atmosphere, is raised in the form of 

 heavy inflammable air. 



He has found, that the fetid odour of animal hepatic air is destroyed by mix- 

 ing it with pure air, and suffering it to remain in contact with that fluid for several 

 weeks. When it was placed in this situation, it acquired an odour which was not 

 exactly similar to any that he had ever before perceived, but which bore some 

 resemblance to that of inflammable air obtained by dissolving iron in spirit of 

 vitriol. The peculiar smell of animal hepatic air is likewise destroyed by agitating 

 it with vinegar, or with the concentrated vitriolic acid. But the fluids which 

 most speedily produce this effect, are the concentrated nitrous and dephlogisti- 

 cated marine acids; and these fluids are known to abound with pure air. It is 

 therefore extremely probable, that this alteration depends on a union between the 

 pure air of the latter substances and the animal hepatic air, or some of its con- 

 stituent parts. 



It appears from the experiments which have been recited above, that in can- 

 cerous and other malignant ulcers, the animal fibres undergo nearly the same 

 changes which are produced in them by putrefaction, or by destructive distilla- 

 tion. The purulent matter prepared for the purpose of healing the ulcer is, in 

 such cases, mixed with animal hepatic air and volatile alkali. The compound 

 formed by the union of these substances, which may perhaps not improperly be 

 termed hepatised ammonia, decomposes metallic salts, and acts on metals: for we 

 have seen, that when it was placed in a jar over mercury for several days, the 

 surface of the mercury acquired a black colour; and that it instantly occasioned 

 a dark precipitate in a solution of nitrated silver. These facts seem to afford an 

 explanation of the changes produced in metallic salts, when they are applied to 

 malignant ulcers. The volatile alkali combines with the acid of the metallic salt, 

 and the animal hepatic air revives the metal, either by imparting to it the inflam- 



