2 It) 



Other liquids^, 

 or even fclids 

 ■may affeft the 



jefult. 



Hiftory of the 

 fcience of the 

 expanfions of 

 gafes, &c. 

 Amontons. 



Amontons's re- 

 fults on common 

 air 



♦mechanically 

 comprefTed. 



t>II«ATATION OP THE GASE*. 



fons, I ft. by the lofs of its caloric ; 2d. by that of the water! 

 held in folutioli. Too much dilatation will be here alfo attri- 

 buted io the air. 



In general, whenever liquids, or even folids, as for exam- 

 ple, muriate of ammonia are inclofed in gafes capable of dif- 

 folving them, or of evaporating at the temperature to which 

 they may be expofed, errors in the determination of the gafe* 

 ous dilatations muftneceflarilyrefult. 



Art. II. Short Account oftvliat has been afcertained concern* 

 ing the Dilatation of Gafes. 



The dilatation of atmofpheric air by heat was known before 

 the time of Amontons ; but it appears that this philofopher 

 was the firft who wiflied to know the extent for a given ele- 

 vation of temperature. For this purpofe he enclofed air in a 

 ball foldered to the extremity of one of the branches of a r'e- 

 verfed fyphon, and he plunged this apparatus into a bath of 

 hot water *. The air dilated by the heat comprelfed the mer- 

 cury, and elevated it into the other branch of the fyphon ; fo 

 that he judged of the fpring of the air by the height of the 

 mercury above the level of the ball. 



From the various experiments made on unequal volumes of 

 air he concludes : {Mem. de V Acad. 1 699, 1702.) 



1ft. ** That the heat of boiling water has limits, beyond 

 which it does not pafs. 



2d. " That unequal volumes of air equally augment the 

 force of their fpring by equal degrees of heat, and on the 

 contrary. 



3d. " That the heat of boiling water does not augment the 

 force of the fpring of air beyond the power of fuftaining about 

 ten inches in height of mercury. " 



He then proves, that however comprefTed a volume of air 

 may be, the heat of boiling water always augments the force* 

 of its fpring about one third • that is to fay, that a volume of 

 air comprefTed, for example, by a column of mercury of 60 

 inches, will fuftain (including the weight of the atmofphere}, 

 at the temperature of boiling water, a column of mercury of 



*" The air enclofed in the ball, not being able to efcape when 

 mercury is poured in, is found a little lefs in volume than it natu- 

 rally is j but if no other preffure is defired than that of the atmo- 

 sphere, it will be very eafy to avoid this flight inconvenience. 



aboufci 



