VOL. LXXX.] PHILOSOPHICAL TRANSACTIONS. ^i$ 



termediate state between the aerial and the vapourous ; this fluid not being per- 

 manently elastic like air, nor immediately condensed by cold like vapour, but 

 gradually assuming the non-elastic form, in consequence probably of the ten- 

 dency of its several parts to unite with each other. The air producetl in the 

 foregoing experiment rendered lime-water turbid ; it therefore contained a quan- 

 tity of fixed air ; and towards the end of the distillation a little volatile alkaline 

 air came over, agreeably to the observation of M. Berthollet : for when a por- 

 tion of the air received during this part of the process was mixed with an equal 

 quantity of marine acid air, a white vapour was produced, and a diminution of 

 about -^ of the whole took place. 



Dr. C. endeavoured, by the following experiment, to ascertain the proportion 

 of fixed air contained in the aerial fluid which is disengaged from the lean of 

 animal substances by heat. A quantity of air, extricated from the lean of fresh 

 mutton, was received over mercury in a large phial with a narrow neck. When 

 the phial was a little more than half filled, the remaining portion of the mercury 

 was displaced by introducing water that had been previously boiled. The phial 

 being then closely corked, the air and water were briskly agitated together ; and 

 the liquor, thus impregnated with the soluble part of the animal air, was put 

 into a proof, to the bottom of which heat was applied. By this means a portion 

 of the air was again disengaged, which was received in a tube inverted over 

 mercury. The process was continued till the liquor in the proof no longer ren- 

 dered lime-water turbid. As the air received in the tube contained the fixed air 

 that had been extricated from the liquor, together with a quantity of common 

 air expelled from the proof, it was a 2d time agitated with water ; and the exact 

 measure of the fixed air was known by the portion which the water imbibed. 

 The fixed air, thus ascertained, being compared with the entire quantity of air 

 that had been originally absorbed, it appeared, that the former was to the latter 

 in bulk as 1 to 4. Therefore J- of the volume of the soluble part of animal air 

 consists of fixed air, and the remaining -f- of hepatic, mixed with a very small 

 proportion of alkaline air. 



It appeared from the experiment, that animal hepatic air, when it was ab- 

 sorbed by water, was not capable of being again disengaged by a heat which 

 raised the water to the boiling temperature ; for, after the fixed air was expelled, 

 the liquor in the proof was made to boil nearly half an hour, but no perma- 

 nently elastic fluid could be disengaged. The portion of the liquor which now 

 remained had a faint yellow colour ; it smelled strongly of animal hepatic air, 

 and deposited a brown precipitate on the addition of nitrated silver. It appears 

 therefore, that the soluble part of the air which is disengaged from the lean of 

 animal substances by heat, consists of 3 distinct fluids ; of alkaline air, fixed 



