VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. 72/ 



fat, and weighing each I dram, were then exposed to these airs. At the end of 

 3 days the piece that was in contact with the common air had not altered its co- 

 lour or consistence, but smelled a little putrid. The colour of the fatty parts of 

 the piece that was exposed to the hepatic air was changed to a dark green, the 

 muscular fibres were cracked and shrivelled on the surface as if they had been 

 seared with a hot iron, and the whole had acquired a soft consistence. 



Similar trials were made with 2 pieces of fresh veal, one of which was exposed 

 over mercury to common air, and the other to air extricated from putrid veal by 

 distillation. The former in 3 days had not changed its appearance; the latter had 

 become green round the edges, and was interspersed with green spots. The sur- 

 face of the mercury in the jar which contained the last had acquired a brown co- 

 lour; whereas that of the mercury in the jar which contained the common air 

 was clear and bright. The pieces of veal were suffered to remain in this situa- 

 tion for 6 weeks. After a few days had expired, that which was exposed to the 

 animal air did not appear to suffer any further change. Its colour, which in the 

 course of a week had become brown, continued unaltered, and no dissolution 

 took place. The air at the last was very fetid ; it occasioned a copious precipitate 

 in lime-water; it was highly inflammable, and burned with a blue lambent flame. 

 On the contrary, the piece which was exposed to the common air, did not, as 

 has been already observed, so soon lose its fibrous texture, nor so speedily ac- 

 quire a dark colour, as that which was in contact with the animal air. But the 

 progress of its putrefaction did not appear to stop at the end of a few days, as in 

 the latter instance. It advanced slowly, and at the end of 6 weeks a consider- 

 able part of the muscular fibres had run down to a brown liquid. The air in 

 which it was placed now occasioned a copious precipitation in lime-water, and 

 the brown liquid was found to be impregnated with animal hepatic and fixed air; 

 the existence of the latter being known by means of lime-water, and that of the 

 former by its occasioning a dark precipitate in a solution of nitrated silver, as 

 well as by its fetid odour, which was increased by the vitriolic, and destroyed by 

 the concentrated nitrous and dephlogisticated marine acids. 



The following experiment was made with a view to determine whether pure air 

 accelerates the progress of putrefaction in animal substances. In the month of 

 Dec. 1789, equal portions of pure and of common air were introduced into 2 

 equal jars over mercury, in each of which was placed about 2 drams of fresh 

 beef. At the end of a week, the beef which was exposed to the pure air had 

 become highly putrid ; but very little change was produced in that which was ex- 

 posed to the common air. 



The facts which have been ascertained by the preceding experiments, appear 

 to lead to the following conclusions respecting the process of putrefaction in the 

 lean of anima\ substances. The muscular fibres of animals contain fixed and 



