432 ^ Jiemarh mjWxed Gnsrs, 



' Above the temperature of 65° Mr. Schmidt 

 seems to think! the force of steam in air the 

 same' .as the force of pure steam of the same 

 temperature ; which is the principle I maintain 

 for the -whole scale; but below that temper- 

 ature he infers from teh above table, compared 

 with that shewing the expansion of pure steam, 

 that steam mixed -or combined (whichever it 

 be) with air, has less force than when pure. — 

 This* deviation arises from his operating with 

 a variable pressure; if he had done in the 

 manner ihavc, namely, have kept a uniform 

 atmospheric pressure at all temperatures, and 

 marked the expansion accordingly, he would 

 have found, as I did, that the expansive force 

 of vapour in any part of the scale of temper- 

 ature is precisely the same when mixed with 



