DILATATION OF THE GASES. Jll 



. about 80 inches. He concludes from this, " That the fame Much force from 

 degree of heat, however fmall it maybe, can always more [^^"turfm^ 

 and more augment the fpring of air, if this air bears a weight condenfed air. 

 more and more great." 



If Amontons had begun to reckon from a degree of heat Amontons had 

 better determined than that which he called temperate, which ^Te therraowcl 

 was then hardly poffible, there might have been deduced from ter. 

 his experiments a fufficiently exact dilatation of atmofpheric 

 air ; neverthelefs, as he made them comparatively on volumes 

 of air of very unequal denfity, it may be concluded that how- 

 ever denje a volume of air may be, the augmentation of fpring it 

 receives from the fame degree of heat, is always relative to that it 

 poffeffed before the experiment, 



Nuguet, in endeavouring to verify the refults of Amontons, Nuguet's expe* 



found others very different. In one of his experiments, the "ments differed 



i n • «-i t <•«•!« ii from thofe of 



Volume of air dilated by the heat or boiling water, and the Amontons* 



primitive volume were as 2 to 1, and in two others as 16 to 1. 

 His apparatus confifted of a bottle, which he plunged reverfed 

 into a water bath, and elevated its temperature to that of 

 boiling water. It is eafily feen that this apparatus is ex- fcecaufe his air 

 tremely defective, as the air was always in contact with the was in contact 

 water ; and befides, Nuguet had fufFered fome water to re- 

 main in the bottle. It is no wonder then that he obtained 

 iuch difproportioned and extravagant refults. {Mem, de UAcad. 

 HOS. Lahire.) 



This great difference between the refults of Amontons and Lahlre's repeti- 

 Nuguet on the dilatation of atmofpheric air, and the confide- \™f^™*~ 

 ration that they had fubmitted it to experiments under uncom- ments. 

 raon circumftances, engaged Lahire to purfue the fame ob- 

 ject. His apparatus was the fame as that of Amontons, ex- 

 cepting that the ball contained a tube, which he clofed after 

 having introduced mercury. By this means, the mercury be- ; 

 itig on a level with the ball and fyphon, the air on which the 

 experiment was made, was not more comprefJed than the fur- 

 rounding atmofphere. With this apparatus Lahire founds 

 that air dilated from the degree of temperate to that of boiling 

 water, could not fuftain a column of mercury of one third the 

 Weight of the atmofphere ; he then found in another, the ther- 

 mometer being lower, and the barometer higher than in the 

 £rft experiment, that the air dilated by the heat of boiling 

 water, could not fuftain a column of mercury as great as in 



P2 the 



