Miscellaneous information. 223- 



fcarcely attainable in thefe experiments. Let us now con- 

 sider the fecond hypothefis. 



In the. Philofophical Journal, Vol. III. page 130, there is Mr. Dalton's 

 a very important paper of Mr. Darton's on the Expanfion of ypot 

 Elaftic Fluids, where he fays, tc In order to explain the man- 

 ner in which elaftic fluids expand by heat, let us aflume an 

 hypothefis, that the repulfive force of each particle is ex- 

 actly proportional to the whole quantity of heat combined 

 with it, or in other words, to its temperature reckoned from 

 the point of total privation : then, fince the diameter of each 

 particle's fphere of influence is as the cube root of the fpace 



occupied by the mafs, we fliall have ^/lOOO: ^1325 (10:11 

 nearly) : : the abfolute quantity of heat in air of 55 Q : the 

 abfolute quantity in air of 212°. This gives the point of total 

 privation of heat, or the abfolute cold, at 1547 Q below the 

 point at which water freezes." 



According to this hypothefis, I have computed the follow- Computations of 

 ing numbers, where the fame is to be underftood as in the laft ^° fa ma e e m 

 table, except the degrees in the firft column, which are thofe 

 of the centigrade thermometer. 



Celfius. Fahrenheit. 



-v/1000 : <J 1 325 : : 10 : 10.983446, 

 which places the real zero at - -— 874,°.12=— -1573°. 43 



-v/1000 : y/1375 : : 10 : 11.1199, 

 which fixes it at - - - —892.93=;— 1607.29 



-V/H67 : yM~325 :: 10.528 : 10.9S34, 

 nearly, which gives - — 952.34= — 1714.2 



^/lOOO : -y/lTo7 :: 10 : 10.528268, 

 and the real zero is at - - —827.77=— 1485.98 



Thefe deductions do not differ nearly fomuch as thofe in the Thefe refults 

 firft table ; yet they give grounds for believing that the fup- XJJ^JSjjL* 

 pofition, or the greater part of the experiments is erroneous. 

 It is no fupport to the validity of this hypothefis to fay, that 

 the firft number nearly agrees with one deduced from a me- 

 thod totally different; for it might have been confiderably 

 greater or lefs than it is, and yet have been nearly equal to 

 pne of thofe in the firft table. There feems to be a flip in the 

 degrees mentioned in Mr. Dalton's paper; for 167 + 158 = 

 325, the whole dilatation between 55* and 212°, while 77±* 

 5 +77f* 



