Mr. Cavendish’s Experiments on Air. 3 8 J 
contained any phlogifticated air, all this. phlpgifticated air, 
joined to as much of the dephlogifticated air as mu ft unite to it 
in order to reduce it into acid, that is, two or three times its 
bulk, would disappear, and no more; fo that the whole dimi- 
nution could not exceed three or four times the bulk of the 
phlogifticated air ; whereas, if the diminution proceeded from 
the burning of the inflammable matter, the purer the dephlo- 
gifticated air was, the greater and quicker would be the dimi- 
nution. 
The refult of the experiments was, that when dephlo- 
gifticated air, containing only W, of its bulk of phlo- 
gifticated air, (that being the pureft air I then had), was con- 
fined between fliort columns of foap-lees, and the fpark pafled 
through it till no further diminution could be perceived, the 
air loft _To of its bulk ; wdiich is not a greater diminution than 
might very likely proceed from the firft-mentioned caufe ; as 
the dephlogifticated air might eafily be mixed with a little 
common air while introducing into the tube. 
When the fame dephlogifticated air was confined between 
columns of diftilled water, the diminution was rather greater 
than before, and a white powder was formed on the furface of 
the quickfilver beneath ; the reafon of which, in all probabi- 
lity, was, that the acid produced in the operation corroded 
the quickfilver, and formed the white powder; and that the 
nitrous air, produced by that corrofion, united to the dephlo- 
gifticated air, and caufed a greater diminution than would 
otherwife have taken place. 
When a folution of litmus was ufed, inftead of diftilled 
water, the folution foon acquired a red colour, which grew 
paler and paler as the fpark was continued, till at laft it be- 
came quite colourlefs and tranfparent« The air was diminiftied 
Vol. LXXV. Eee by 
