Acidity , the Decomfojition of Water , and Phlogijlon, 3 1 5 
acid, by its making a precipitation with a folution of filver in 
nitrous acid. But this mixture of marine acid, he obferves, 
is conftantly found to accompany the produftion of nitre in 
the operations of nature. Whether the different fubftances 
from which the dephlogifticated air was extracted made any 
difference in this cafe, I cannot tell ; but that which I gave Dr. 
Withering was from minium, and that which Mr. Keir 
examined was from manganefe. 
: In the notes which i took of the firft production of this 
liquor I termed it blue , and Dr. Withering alfo calls it blue, 
and once a greenijh blue ; but that which I gave Mr. Keir, 
and all that I have got fince, is a decided and deep green , 
which Mr. Keir thinks to be owing to the phlogiftication of 
the nitrous acid. 
Thofe philofophers who are unwilling to admit the doftrine 
of phlogifton, will perhaps fay, that, in thofe experiments in 
which a calx is revived by means of inflammable air, this 
air joins the dephlogifticated air that w*as in the calk ; and 
that, in confequence of this, the metal, being freed from a 
foreign fubftance, refumes its proper form and qualities, with- 
out having received any addition whatever. 
But fince it appeared in the preceding experiments, in which 
inflammable air was procured by means of fteam, that the 
metal did not become a calx, except in confequence of parting 
with inflammable air (or rather with fomething which, when 
united to water, is inflammable air) it cannot be fup- 
poled to recover its metallic form without re-imbibing the 
fame thing that it had loft, which thing may be termed 
■phlogijlon, 
Confequently, inflammable air being (in the opinion of 
thole who do not admit the do&rine of phlogifton) the fame 
Vo l. LXXVIII. U u thing 
