Mr . C A V r, N D I sn' s Experments on Atr, 38 1 



in the latter from turbith mineral. In the firft experiment, the 

 quantity of foap-lees iifed was 3 ; meafures, each of which was 

 equal in bulk to one grain of quickfilver ; and that of the air 

 abforbed was 416 fuch meafures- of phlogifiicated air, and 914 

 of dephlogifticatedi.. }n the fccond experiment, 778 meafures 

 of fonp-leea were nfed, nnd they abforbed 1920 of phlogifti- 

 cated air, and 48^0 of dephlogilricated. It mulf be obferved, 

 however, that m b<^th experiments fome air remained in the 

 tube uucondcnfed,- whafe degree of purity I had no way of 

 trying; fo that the pTop&rtion.of" each fpecies of air abforbed is 

 not known with mucli exaclneisi 



As far a.s the experiments- hitherto publiflled extend, we 

 fcarcely know more of the nature of the phlogifticated part of 

 our atm.ofphere, than that it is not diminilh^d by lime-water, 

 caultic alkalies, or nitrons air; that it i3 unfit to fupport fire^ 

 or maintain lit© in animals ;- and that its fpecific gravity is' 

 not much lefs than that of common air : fo that, though the 

 nitrous- ncid, by being united to phlogilfon, is converted into 

 air policlicd of thefe properties, and confequently, though it 

 was reafonable to fuppofe, that part at leaft ot the phlogiill- 

 cated air of the atmofphcre confifts-of this acid united 'to phiO- 

 gilfon, yet it miglit fairly be doubted .whether the whok is of 

 this kind, or whether there are not in reality many ditfeTent 

 fubftances confounded together by. us under the name of phlo- 

 gifticated air. h therefore made an experiment to determiney 

 whether the whole of a. given iportion of tlie pklogifticatcd air 

 cf the atmofphere could be reduced to nitrous acid, or whether 

 there was not a part of a different nature from the reft, which 

 v^ould refufe to undergo that change. The foregoing experi- 

 ments indeed in fome meafure decided this point, as much the 

 greatefl: part of the air let up into the tube loft its elaftlcity;. 



yet. 



