402 PHILOSOPHICAL TRANSACTIONS. [aN'NO 1784. 



found in the condensed liquor may be explained ; first, by supposing that dephlo- 

 gisticated air contains a little nitrous acid which enters into it as one of its com- 

 ponent parts, and that this acid, when the inflammable air is in a sufficient pro- 

 portion, unites to the phlogiston, and is turned into phlogisticated air, but does 

 not when the inflammable air is in too small a proportion ; and, secondly, by 

 supposing that there is no nitrous acid mixed with, or entering into the composi- 

 tion of, dephlogisticated air, but that when this air is in a sufficient proportion, 

 part of the phlogisticated air with which it is debased is, by the strong affinity 

 of phlogiston to dephlogisticated air, deprived of its phlogiston, and turned into 

 nitrous acid ; whereas, when the dephlogisticated air is not more than sufficient 

 to consume the inflammable air, none then remains to deprive the phlogisticated 

 air of its phlogiston, and turn it into acid. 



If the latter explanation be true, I think we must allow that dephlogisticated 

 air is in reality nothing but dephlogisticated water, or water deprived of its phlo- 

 giston ; or, in other words, that water consists of dephlogisticated air united to 

 phlogiston ; and that inflammable air is either pure phlogiston, as Dr. Priestley 

 and Mr. Kirvvan suppose, or else water united to phlogiston ;* since, according 

 to this supposition, these two substances united together form pure water. On 

 the other hand, if the first explanation be true, we must suppose that dephlo- 

 gisticated air consists of water united to a little nitrous acid and deprived of its 

 phlogiston ; but still the nitrous acid in it must make only a very small part 

 of the whole, as it is found, that the phlogisticated air, which it is converted 

 into, is very small in comparison of the dephlogisticated air. 



I think the second of these explanations seems much the most likely ; as it 

 was found, that the acid in the condensed liquor was of the nitrous kind, not 

 only when the dephlogisticated air was prepared from red precipitate, but also 



* Either of these suppositions will agree equally well with the following experiments ; but the 

 latter seems to me much the most likely. What principally makes me think so is, that common or 

 dephlogisticated air do not absorb phlogiston from iuflammable air, unless assisted by a red heat, 

 whereas they absorb the phlogiston of nitrous air, liver of sulphur, and many other substances, with- 

 out that assistance ; and it seems inexplicable, that they should refuse to unite to pure phlogisto^ 

 when they are able to extract it from substances to which it has an affinity ; that is, that they should 

 overcome the affinity of phlogiston to other substances, and extract it from them, when they will not 

 even unite to it when presented to them. On the other hand, I know no experiment which shows 

 inflammable air to be pure phlogiston rather than a union of it with water, unless it be Dr. Priestley's 

 experiment of expelling inflammable air from iron by heat alone. I am not sufficiently acquainted 

 with the circumstances of that experiment to argue with certainty about it ; but I think it much 

 more likely that the inflammable air was formed by the union of the phlogiston of the iron filings 

 with the water dispersed among them, or contained in the retort or other vessel in which it was 

 heated ; and, in all probability this was the cause of the separation of the phlogiston, as iron seems 

 not disposed to part with its phlogiston bv heat alone, without being assisted by the air or some 

 other substance. — Orig. 



