722 PHILOSOPHICAL TRANSACTIONS. [aNNO l/QO. 



was then added, and the mixture being fired, its bulk was increased from .9 of 

 an inch to 1.3 inch. 



Three measures of this residuary air were then mixed with 3 of pure air, and 

 fired by the electric shock* The bulk of the mixture was reduced from I inch 

 to .56. This being agitated with lime-water, ^ were absorbed, and the re- 

 mainder consisted almost wholly of pure air. From these facts it seems proba- 

 ble, that animal hepatic air consists of a combination of heavy and light inflam- 

 mable air ; and that when it is fired with a quantity of pure air not sufficient to 

 saturate it, a portion of the animal air is resolved into its elementary principles, 

 in consequence of which its bulk is increased. 



Dr. C. was next desirous of learning whether an increase of size would be 

 produced by making the electric shock pass through a mixture of pure and alka- 

 line air. Having first accidentally taken !2 or 3 small shocks through a little 

 alkaline air, and not observing a sensible augmentation of bulk, he then mixed 

 it with an equal volume of pure air ; and, as he supposed that no decomposition 

 had taken place, he was not apprehensive of an explosion. Contrary however 

 to expectation, the airs, when the electric shock was made to pass through them, 

 entered rapidly into a union with each other. The jar which he held loosely in 

 his hand, as it was inverted over the mercury, was carried obliquely upwards 

 with great violence. Having broken the stand of the prime-conductor in its 

 passage, it forced its way through the cylinder of the electrical machine, which 

 it shivered to a thousand pieces. Dr. C. afterwards repeated this experiment 

 with a very strong apparatus, the jar being pressed down by a plate of iron, foF 

 the purpose of retaining it in its place. It appeared, that when the alkaline and 

 pure air were immediately mixed together, and a small shock was made to pass 

 through them, they would not take fire ; but when 3 or 4 shocks were previously 

 taken through the alkaline air, and the latter was afterwards mixed with an equal 

 bulk of pure air, they exploded with great violence. The residue, having 

 cooled to the temperature of the surrounding air, was reduced to half the 

 original bulk of the mixture. Of this residue ^ was undecomposed alkaline air. 

 The remainder was phlogisticated air. 



Of the products which result from the combustion of sulphureous hepatic with 

 pure air. — The hepatic air employed in the following experiments was procured, 

 agreeably to the method which Mr. Kirwan has recommended, by adding 

 marine acid to an artificial combination of sulphur and iron. Three measures 

 of the air thus obtained were mixed in a strong glass tube over mercury, with 4 

 of pure air, and fired by the electric shock. 



The pure air was previously agitated with lime-water to free it from fixed air, 

 and a portion of the hepatic air, having been likewise agitated with lime-water, 

 was found not to occasion any precipitation in that fluid. The airs were re- 



