3 1 S Dr . Priestley’s Experiments and Obfervations on 
ence of the atmofphere till it becomes phlogifticated air, as 
may be feen in my former experiments. In this manner I 
now always treat the bladders in which 1 make experiments on 
air. It prevents them from putrefying, and gives them a 
firmnefs of texture fimilar to tanning. 
That nitrous air contains water, and that this water can 
contribute to the formation of fixed air, is evident from the 
following experiment. I heated five grains of charcoal of 
copper in eight-ounce meafures of nitrous air, till it was in- 
creafed to ten-ounce meafures, and the charcoal had loft one 
grain. Examining the air, I found about one-fifth of it to be fixed 
air, and the remainder phlogifticated. It feems, therefore, that 
nitrous air confifts of water, and fomething that may be called 
the balls of nitrous acid, or that fubftance which, when united 
to dephlogifticated air, will make nitrous acid ; and this feems 
to be pure phlogifton, fince it is found, as the preceding expe- 
riments fhew, in the purefl inflammable air. May we not 
hence infer, that the nitrous is the fimplell of all the acids, 
and perhaps the balls of all the reft ? 
It is evident, that more water than enters into the compoft- 
tion of nitrous air is neceflary for the change of it into what 
I have called dephlogijiicated nitrous air , becaufe the contact of 
iron will not, without water, produce that change in it. 
Though fixed air, as I have fhewn, contains water as well 
as nitrous air, it cannot be deprived of it, and be decompofed, 
by the fame means ; for I have heated iron in it by a burning 
lens, and have alfo made it pafs repeatedly through a hot 
earthen tube containing turnings of iron, without producing 
any change in it. 
In the former Paper I faid, that manganefe of itfelf gives 
only the pureft dephlogifticated air by heat ; but I have now 
a quantity 
