j82 Mr. CAVE-smsfCs Experiments on Air, 



yet, :^,o iome remained unablorbed, it di^^ not appear for certain 

 whether that, <was at the fame nature as the reft or not. For this 

 purpofe I dlminiihed a iimiiar mixtu:e of dephlagifticated and 

 common air, in the lame manner as before, till it was reduced to a 

 fmall part of its original bulk. I then, in order todecompor.nd 

 as much asIcould.ot" the phlogiilicated air which remained in-j 

 the tube, added i^niQ dcpiilogiilicated air to ir, and continued the 

 ipark till no furtht;r diminution took phice. Having by thefe" 

 means condenfed as much as I could of the phlogldicated air, I- 

 iet up ibme folution of liver of fulphur to abforb the deplilo-; 

 gilficated air ; after which only a fmall bubble of air remained 

 unabforbcd, wliich certainly was rjot more than ^L.^ of the 

 bulk of the phlogifticated air let up into the tube; fo that if 

 there is any part of the phlogiilicated air of our atmofpher©. 

 which ditters from the rell, and cannot be reduced to nitrous ' 

 acid, we may fafely conclude^ that it is not more than t-t^- 

 part of the whole. 



The foregoing experiments fhew, that the chief caufe of. 

 the diminution which common air, or a mixture of common^, 

 and dephlogiilicated air, fuffers by the ele€lrlc fpark, is the 

 converfion of the air into nitrous acid; but yet it feemed not: 

 unlikely, that when any liquor, containing inflammable mat- 

 ter, was in contacl with the air ia the tube, fome of this : 

 matter might be burnt by the fpark, and thereby diminifh the • 

 air, as I fuppofed in the above-mentioned Paper to be the cafe. 

 The bed way which occurred to me of difcovering whether 

 this happened or not, was to pafs the fpark through dephlogiifi- •■ 

 cated airj included between different liquors: for then, it the 

 diminution proceeded folely from the converlion of air into 

 nitrous acid, it is plain that, when the dephloglfticated air was i 

 perfedlly pure, no diminution would take place ; but when it » 



contained 



