40 6 Dr. Priestley's Experiments relating to Phlogijlon , 
and to have no fixed air in it. At another time, in eight ounce 
meafures of alkaline air I got 1 5 grains of lead, befides what 
was diffolved in the mercury, which feemed to be a good deal 
in proportion to it. It was obfervable, that there remained in 
this prpeefs 3! ounce meafures of phlogifticated without any 
mixture of fixed air in it, though the maflicot which I ufed at 
this time gave by heat only a good deal of pretty pure fixed 
air. Tliefe experiments with alkaline air well deferve to be 
refumed, and Ilhall not fail to do it at a proper opportunity. 
Having thus produced lead in inflammable air, I proceeded 
in my attempts to revive other metals from their calces by the 
lame means ; and I fucceeded very well with tin, bifmuth, and 
filver ; tolerably well with copper, iron, and regulus of co- 
balt ; but not at all with regulus of antimony, regulus of ar- 
fenic, zinc, or the metal of manganefe. 
I was defirous alfo of afeertaining by this means the quantity 
of phlogifton that enters into the compofition of the feveral 
metals ; but in this I found more difficulty than I had expedfed : 
and this arofe chiefly from the allowance that was to be made 
for the inflammable air which entered into that part of the 
calx which was only partially revived ; and it was not eafy to 
revive the whole of any quantity of calx completely. 
After many trials, I think I may venture to fay, that an 
ounce of lead abforbs 100 ounce meafures of inflammable air, 
or perhaps fomething more ; for in one refult it feemed to have 
imbibed in the proportion of 108 ounce meafures. 
An ounce of tin abforbs inflammable air in the proportion of 
377 ounce meafures to the ounce. An ounce of copper from 
verditer abforbed 463 ounce meafures ; from a folution of blue 
vitriol, precipitated by fait of tartar, and afterwards made red- 
hot with fpirit of nitre, 640 ; but from blue vitriol itfelf 909 
4 
ounce 
