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(that is beneath 170^), and moft in the loweft, and in thofe 

 whofe bore is fmallefl ; hence much heat is loft in vanquifhing 

 this adherence, and, when it rifes or falls, it does fo by irregular 

 •jumps or ftarts, to fay nothing of the internal inequalities of 

 the bore, nor of the adherence of the mercury which confines 

 the air. 



The perfon who, as appears to me, has moft fuccefsfuUy 

 ■avoided or leffened moft of thefe obftacles is Mr. .Schmivjc, 

 Profeffbr at Gieffen. The defcription of Jiis apparatus is too 

 prolix for infertion and cannot be underftood without a plate. 

 It may be feen in 4 Gren's Journal. His experimeuts were made 

 partly on air artificially dried, and partly on air artificially 

 moiftened, but the degree of moifture was determined by no 

 known hygrometer. However he found the expanfions of 

 dry air to be exadlly proportional to the degrees of heat it was 

 expofcd to, and in this point he agrees with D'Amontons, Lam- 

 bert and De Luc. Sir George .Schuckburg, abating fome in- 

 confiderable variations, draws the fame conclulion in all heats 

 from 32*^ to 83^ under a preflion of 30,5 inches of mercury, 

 and infers from the mean of thirteen experiments that 1000 

 meafures of air gain 2,43 by each degree of Fahr, above 32° 

 and gain the fame increafe under a prefTure of 40 inches or 

 23,5 inches of mercury. This laft point however is contra- 



dided 



