128 On Sir H. Davy's Theory of [Aug. 



hand, should, in consequence of so slight a combination, be 

 rendered incapable of performing this office. This supposition 

 seems quite as difficult to be maintained as the one which is 

 necessary to reconcile the fact to the old theory ; and which has 

 been laid hold of as an argument against that explanation, viz. 

 that " this muriatic acid with one dose of oxygen supports 

 combustion, and with an additional dose becomes a non- sup- 

 porter." Improbable as this supposition seems at first sight, we 

 are furnished with a nearly analogous instance in the actions of 

 nitric and nitrous oxides on living animals. Besides, owing to 

 the great facility with which this gas is decomposed, the heat to 

 which the substances experimented on could be exposed must 

 have been very trifling, and far below what is necessary to cause 

 their inflammation in pure oxygen. 



We are now prepared to examine Sir H. Davy's theory of 

 hyper-oxymuriate of potash, which he holds to be composed of 

 euchlorine united to peroxide of potassium. We are not as yet 

 in possession of any very decisive analysis of this peroxide ; but 

 Sir H. Davy mentions, that with 2 grains of potassium he ob- 

 tained an absorption of 2 6 cubic inches of oxygen, the weight 

 of which quantity is 'S84 of a grain : while it appears probable 

 that 2 gTains of potassium, in passing to the state of potash, 

 absorb only *278 of a grain, being rather less than one-third of 

 the quantity taken to form the peroxide. According to Chenevix, 

 100 grs. of hyper-oxymuriate of potash contain 39"2 grs. of 

 potash. Now in passing to the state of peroxide, this quantity 

 will absorb 21*981 16 grs. of oxygen : but since from 100 grs. of 

 the salt 38*478 grs. of oxygen may be obtained, there remain 

 1 (J -49684 grs. which must enter into combination with the 

 chlorine to form euchlorine. Sir H. Davy says, as was already 

 remarked, that this gas consists of 2 of chlorine united to 1 of 

 oxygen. If by volume, their relative weights must be as 725 to 

 1/0; and in this proportion, 16*496S4 grs. of oxygen require 

 69-86616 grs. etf chlorine, a quantity exceeding by 44*05971 

 grs. the weight of what the salt may be conceived to contain. If 

 Sir H. Davy means, that 2 by weight of chlorine unite with 1 

 by weight of oxygen (which, from his adducing it in illustration 

 and corroboration of the theory of definite volumes in gases, \ 

 cannot think he does), the weight of chlorine required is 

 32*99368 grains, which still considerably exceeds 25-80645 

 grains (the quantity contained in 100 grs. of the salt), and 

 which differs yet more from 19*263 grs. the proportional quan- 

 tity as ascertained by calculation on Sir H. Davy's principles 

 from the quantity of muriate of potash formed along with the 

 hyper-oxymuriate. 



According to the old theory, 100 grs. of potash, with a« 



1 



