20 PHILOSOPHICAL TKANSACTIONS. [aNNO 1785. 



when combined with dephlogisticated air, the above-mentioned opinion seems to 

 be sufficiently established. A further confirmation of it is that, as far as I can 

 perceive, no diminution of air is produced when the electric spark is passed either 

 through pure dephlogisticated air, or through perfectly phlogisticated air; which 

 indicates the necessity of a combination of these two airs to produce the acid. 

 It was also found in the last experiment, that the quantity of nitre procured was 

 the same that the soap-lees would have produced if saturated with nitrous acid; 

 which shows that the production of the nitre was not owing to any decomposition 

 of the soap-lees. It may be worth remarking, that whereas in the detonation 

 of nitre with inflammable substances, the acid unites to phlogiston, and forms 

 phlogisticated air, in these experiments the reverse of this process was carried on; 

 namely, the phlogisticated air united to the dephlogisticated, which is equivalent 

 to being deprived of its phlogiston, and was reduced to nitrous acid. 



In the above-mentioned paper I also gave my reasons for thinking that the 

 small quantity of nitrous acid, produced by the explosion of dephlogisticated and 

 inflammable air, proceeded from a portion of phlogisticated air mixed with the 

 dephlogisticated, which I supposed was deprived of its phlogiston, and turned 

 into nitrous acid, by the action of the dephlogisticated air on it, assisted by the 

 heat of the explosion. This opinion, as must appear to every one, is confirmed 

 in a remarkable manner by the foregoing experiments; as from them it is evident 

 that dephlogisticated air is able to deprive phlogisticated air of its phlogiston, 

 and reduce it into acid, when assisted by the electric spark; and therefore it is 

 not extraordinary that it should do so when assisted by the heat of the explosion. 



The soap-lees used in the foregoing experiments were made from salt of tartar 

 prepared without nitre; and were of such a strength as to yield -pL of their 

 weight of nitre when saturated with nitrous acid. The dephlogisticated air also 

 was prepared without nitre, that used in the first experiment with the soap-lees 

 being procured from the black powder formed by the agitation of quicksilver 

 mixed with lead,* and that used in the latter from turbith mineral. In the first 

 experiment, the quantity of soap-lees used was 33 measures, each of which was 

 equal in bulk to 1 grain of quicksilver; and that of the air absorbed was 4l6 

 such measures of phlogisticated air, and 9 14 of dephlogisticated. In the 2d 

 experiment, 178 measures of soap-lees were used, and they absorbed 1920 of 

 phlogisticated air, and 486o of dephlogisticated. It must be observed however, 

 that in both experiments some air remained in the tube uncondensed, whose 

 degree of purity I had no way of trying; so that the proportion of each species 

 of air absorbed is not known with much exactness. 



As far as the experiments hitherto published extend, we scarcely know more of 



* This air was as pure as any that can be procured by most processes. I propose giving an account 

 of the experiment, in which it was prepared, in a future paper.— Orig. 



