on some of the leading Doctrines of Caloric, Sc. 187 
the corresponding parts of the scale shortened in the successive 
proportions of 62 to 63; 61 to 63; and 60 to 65; quantities 
taken together nearly equal to 9°, or HS Max i80= 540, 
Whatever reception these speculations may experience, they 
must not be confounded with the experiments on the expansions 
of metallic rods, and the corollaries which have a distinct and 
independent existence. 
§ II. On the Doctrines 5 pent as connected with. the 
preceding Investigation. 
Dr. Crawford and De Luc tried to verify the justness of the 
thermometric indications, by mixing together water at 212° and 
32°; when the former found 122°, and the latter 119°, to be 
the resulting temperature. De Luc’s number is 3° below the 
mean; Dr. Crawford’s is exact. This ingenious philosopher 
afterwards sought to confirm the evidence thus given to the ac- 
curacy of the scale, by other experiments, which were however 
of rather an equivocal import. Both of the above results have 
been condemned and rejected by Mr. Dalton : he states the true 
mean temperature to be not 122°, nor even 119°, but 110°. 
For this deviation, the reasons which he assigns appear, inde- 
pendently of all arguments derived from other quarters, to be in 
themselves inconclusive. He says, “‘ the temperature of the 
above mixture ought to be found above the mean 122°.” ‘*Wa- 
ter of these ae temperatures (32° and 212°) being mixed, 
loses about ;!; of its bulk. This condensation of its volume . 
must expel a quantity of heat, and raise the temperature above 
the mean.” p.7. Again, p. 50, that water increases in its ca- 
* pacity for heat with-the increase of temperature, I consider de- 
monstrable from the following arguments. Ist. A measure of 
water at any one temperature mixed with a measure at any other 
temperature, the mixture is less than two measures. Now, a 
condensatioa of volume is a certain mark of diminution of ca- 
pacity and increase offAemperature+, as in the mixture of sul- 
phuric acid and water; or the effects of mechanical pressure, as 
with elastic fluids. Second, when the same body suddenly changes 
its capacity by a change of form, it is always from a less toa 
greater as the temperature ascends ; for instance, ice, water and 
vapour. Third, Dr, Crawford acknowledges from his own: ex- 
perience, that dilute sulphuric acid, and most other liquids he 
tried, he found to increase in their capacity for heat with the in- 
* That condensation of volume in a liquid, is no proof of the expulsion 
of heat, is shown in iny Essay on Sulphuric Acid, 
t For tie entire fallacy of this reasoning, see my Essay just quoted; ex- 
Pansion of volume should by Mr. D. increase capacity ‘and diminish tem-+ 
Perature, The very reverse is shown in that paper. 
crease 
