i j2 Mr. cavendish’s Account of 
The trials, called fontana abridged, were made in the 
Abbe fontana’s manner, except that only one meafure of re- 
fpirable air was ufcd, the nitrous air being added by one mea- 
fure at a time as ufual. The column marked i at top is the 
hulk of the mixture after one meafure of nitrous air was added ; 
that marked 2, its bulk after two meafures were added, and 
fo on. 
It mud: be obferved, that in thefe experiments a confiderable 
diminution took place in taking the ted of the unmixed phlo- 
gidicated air, or that whole dandard is marked o in the table 
but, notwithdanding this, the air, as far as I could perceive, 
was perfectly phlogidicated, the diminution being caufed merely 
by the abforbtion of the nitrous air by the water. What fhewrs 
this to be the cate is, that if common and nitrous air are mixed 
in fuch proportions as that the nitrous lliould be predominant, 
fo as to be confiderably diminished by the mixture of common 
air, this mixture will produce as great a diminution with ni- 
trous air as the phlogidicated air ufed in thefe experiments ; 
and if plain nitrous air is added to nitrous air, the diminution 
is dill greater. This (hews, that a confiderable diminution is 
produced by mixing perfectly phlogidicated air with nitrous air, 
and alfo that air may be perfeflly phlogidicated by liver of 
fulphur. 
Thefe experiments alfo fhew the necedity of uling fuch a 
quantity of nitrous air as is fufficient to produce the full dimi- 
nution, in order to form a proper edimate of the goodnefs of 
air ; for if the quantity of nitrous air is much l'efs than that, 
the air you try will appear very little better than air of a much 
inferior quality. For example, if in taking the ted of very 
good dephlogidlcatcd air, only an equal bulk of nitrous air is 
ufed. 
