HENRY CAVENDISH 107 



kind of air, the air in both being taken from the same bottle, and the 

 experiment tried in the same manner, except that the proportions of 

 inflammable air were different. In the first, in which the burnt air 

 was almost completely phlogisticated, the condensed liquor was not at 

 all acid. In the second, in which its standard was 1.86, that is, not 

 much phlogisticated, it was considerably acid; so that with this air, 

 as well as with that from plants, the condensed liquor contains, or is 

 entirely free from, acid, according as the burnt air is less or more 

 phlogisticated; and there can be little doubt but that the same rule 

 obtains with any other kind of dephlogisticated air. 



In order to see whether the acid, formed by the explosion of dephlo- 

 gisticated air obtained by means of the vitriolic acid, would also be of 

 the nitrous kind, I procured some air from turbith mineral, and ex- 

 ploded it with inflammable air, the proportion being such that the 

 burnt air was not much phlogisticated. The condensed liquor man- 

 ifested an acidity, which appeared, by saturation with a solution of 

 salt of tartar, to be of the nitrous kind ; and it was found, by the addi- 

 tion of some terra ponder osa salita, to contain little or no vitriolic acid. 



When inflammable air was exploded with common air, in such a 

 proportion that the standard of the burnt air was about 4-10, the con- 

 densed liquor was not in the least acid. There is no difference, how- 

 ever, in this respect between common air, and dephlogisticated air 

 mixed with phlogisticated in such a proportion as to reduce it to the 

 standard of common air; for some dephlogisticated air from red 

 precipitate, being reduced to this standard by the addition of perfectly 

 phlogisticated air, and then exploded with the same proportion of in- 

 flammable air as the common air was in the foregoing experiment, the 

 condensed liquor was not in the least acid. 



From the foregoing experiments it appears, that when a mixture of 

 inflammable and dephlogisticated air is exploded in such proportion 

 that the burnt air is not much phlogisticated, the condensed liquor 

 contains a little acid, which is always of the nitrous kind, whatever 

 substance the dephlogisticated air is procured from ; but if the pro- 

 portion be such that the burnt air is almost entirely phlogisticated, the 

 condensed liquor is not at all acid, but seems pure water, without any 

 addition whatever ; and as, when they are mixed in that proportion, 

 very little air remains after the explosion, almost the whole being con- 

 densed, it follows that almost the whole of the inflammable and 



