Mr. Cavendish's Experiments on Air. ^ 383 

 contained any phlogiilicated air, all this phlogiflicated air, 

 joined to as much of the dephlogifticated air as miift unite to it 

 in order to reduce it into acid, that is, two or three times its 

 bulk, would difappear, and no more; fo that the whole dimi- 

 nution could not exceed three or four times the hulk of the 

 phlogiftlcated air : whereas, if the diminution proceeded from 

 the burning of the inflammable matter, the purer the dephlo- 

 giilicated air was, the greater and quicker would be the dimi- 

 nution. 



The refult of the experiments was, that when dephlo- 

 gifticated air, containing only -^.^ of its bulk of phlo* 

 giflicated air (that being the pureft air I then had), was con- 

 fined between (hort columns of foap lees, and the fpark pafled 

 through it till no further diminution could be perceived, the 

 air loft _±^v ^^ i^^ \^\!X^ ; which 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 lurface of 

 the quickiilver 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 corroiion, 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 diminiflied 



Vol. LXXV. E e e by 



