on the fpecific Gravities , &c. of Saline Subfiances . 2 17- 
Thirdly, If the electric fpark be taken through common air, 
this air will be diminifhed one-fourth, and a folution of lime, 
if contiguous, will be precipitated, and a folution of turnfole 
tinged red. 1 pr. 184. 186. Whence could the fixed air here 
produced proceed, but from the common air, and the phlogifton 
of the metallic conductors ? This excellent philofopher has even 
fhewn it could proceed from nothing elfe ; for after that air 
had contributed all it could to that production, that is, was 
diminifhed to the utmoft, he changed the liquors, but could 
produce no change in their colour, nor the leaft fign of fixed air. 
This experiment has alfo been repeated in France, and the 
infide of the glafs tube, in which the common air was con- 
tained, was moiftened with a folution of cauftic fixed alkali, 
and the alkali, after the operation, was found cryftallized ; 
but when the tube was exhaufted of air, and the experiment 
repeated, no change whatfoever was found in the alkali. EJfai 
fur VElettricite, par Air . Le Comte de la cepede, vol. I. 
P- 155- 
Fourthly, If lead and mercury be agitated in a phial, partly 
filled with common air, this air will be diminifhed one-fourth, 
and the refiduum will be found completely phlogifticated. The 
diminution will be ftill greater if the phial contain dephlo- 
gifiicated air. 1 pr. 149 . The lead is converted into a calx, 
calcination being the known effeCt of the amalgamation of 
the bafe metals ; and this calx abforbed the fixed air produced, 
for Dr. priestley expelled this air from it. 1 pr. 144 . ; and 
hence an amalgama of lead and mercury decrepitates when 
heated*. Whence could this fixed air proceed, but from the 
refpirable air ? For furely neither lead nor mercury contain 
any. 
Vol. LXXII. 
* I MALOUIN. IO5. 
F f 
If 
