3 g.8 Dr. Priestley’s Obfervations 
be fixed air, and the refiduum of the ftandard of 1.7. Laftly* 
I heated 8 J gr. of perfect charcoal in 70 oz. m. of dephlogifti* 
cated air, of the ftandard of 0,46, when it ftill continued 70 
oz, m* ; but after wafhing in water it was reduced to 40 oz. 
m. of the ftandard of 0.6, and the charcoal then weighed i£ 
gr. ; fo that from this experiment with common charcoal, as 
well as from the preceding with charcoal of copper, it appears, 
that about one-fourth of the weight of fixed air is phlogifton, and 
confequently that the other three-fourths are dephlogifticated 
air. 
Having done this, I proceeded to afcertain how much fixed 
air was adlually formed by breathing a given quantity both of 
atmofpherical and of dephlogifticated air, in order to determine 
whether any part of it remained to enter the blood, after 
forming this fixed air. 
For this purpofe I breathed in 100 oz. m. of atmofpherical 
air, of the ftandard of 1.02, till it was reduced to 71 oz. nn 
and by wafhing in water to 65 oz. m. of the ftandard of 1.45. 
When the computations are properly made, as directed in a 
former Paper, it will appear, that, before the procefs, this air 
contained 67.40Z. m. of phlogifticated air, and 32.60Z. m.of de- 
phlogifticated air; that after the procefs there remained 53.10 5 
oz. m. of phlogifticated air r and 11.895 oz. m. of dephlogifti- 
cated air ; and that there were only 6 oz. no. of fixed air pro- 
duced ; for the quantity abforbed during the procefs could only 
have been very inconfiderable. It will therefore be evident, that ? 
in this experiment, 20.7 oz. m. of dephlogifticated air, which 
would weigh 12.42 gr. difappeared ; whereas all the fixed air 
that was found would only have weighed 4.4 gr., and one- 
fourth of this being phlogifton, the dephlogifticated air that 
entered into it would have weighed only 3.3 gr. ; confequently 
9.12 
