344 jft>be fontana’s Experiments and 
parts of a meafure I exprefs in common numbers ; 
for inftance, when I fay II- 1 6 and 11 + io, the firft ex- 
preflion means, that after having introduced into the 
tube two meafures of common air, and one meafure of 
nitrous air, the fpace occupied by the mixture of thefe 
two airs was two meafures — 16 parts, or 6oths of a 
meafure: and the fecond expreffion fhews that, after 
having introduced another meafure of nitrous air,, 
the fpace occupied was two meafures + io parts. The 
reafon and particulars of this method will be given here- 
after in a paper exprefsly written upon the method of 
determining the degree of the falubrity of the air by 
means of nitrous and inflammable air. 
Having introduced eight cubic inches of common air 
into the fame bladder, I breathed it as long as I could ; 
beginning after a natural expiration as in the experi- 
ment above related. I breathed it thirty-four times fuc- 
ceffively, and afterwards found it very much altered, fo 
that it extinguished a light many times fucceffively. An 
animal introduced into a veflel of that air immediately 
gave ligns of uneaiinefs : and the air being tried with the 
nitrous air gave 11 + 20, III +15; whereas, before it had 
been breathed, it gave with the fame nitrous air II- 15, 
II+18. 
This 
