160 Mr. Kirwan’s Remarks on 
_ Farther : ‘there is no fubftance which yields dephlogifticated” 
, but yields alfo fixed air, even precipitate per /é not except-" 
ah (3 Priest. £6.) and what is remarkable, they all yield fixed” 
air firft, and dephlogifticated air only towards the end of the — 
procefs. Does not this happen becaufe metallic calces attra& phlo-" 
gifton fo much more ftrongly, as they are more heated? ‘Thus 
raany calciformy iron ores become magnetic by calcination, though’ 
they were not fo before; fo alfo do all the calces of iron when ex-’ 
pofed to the focus ofa burning elafs (5 Did. Chy. 179). Thus® 
vaercury cannot be calcined’ but in a heat inferior to that in which: 
it boils; thus minium cannot be formed but in a moderate heat,’ 
and if heated {till more it returns to the ftate of mafficot, 1 in. 
which it was before it became minium, and much -of it js re=- . 
duced. So if a folution of luna cornea in volatile alkali be tri+ 
turated with mercury, the filver will be revived, and the ma- 
rine acid unite to the mercury, which fhews this acid has a 
ftronget attraction to Mercury than to filver; yet if fublimate’ 
corrofive and filver be diftilled in a {trong heat, the mercury’ 
will be revived, and the marine acid unite to the filver, which 
fhews that the attraction of mercury to phlogifton increafes' 
with the heat applied. ; 
Before I conclude this head, I will mention another experi~' 
ment, which I think decifive in favour-of my opinion of the’ 
compofition of fixed air. If filings of zinc be’ digefted in ‘a’ 
cauftic fixed alkali in a gentle heat, the zinc will be diflolved: 
with effervefcence, and the alkali will be rendered in great 
meafure mild. Butif, miftead of filings of zinc, flowers of zine 
be ufed, and treated in the fame manner, there will be no 
folution, and the alkali will remain cauftic. In the firft cafe 
the effervefcence arifes from the production of inflammable air, 
which’ 
