on some of the leading Doctrines of Caloric, &c. 101 
Tastes VII. and VIII. 
Darton’s Theory of the thermometric Scale compared with the 
observed Temperatures and Tensions of Vapours. 
Aqueous Vapour. ‘Ethereal Vapour. | 
Darron’s Datton’s| oR D : oF 
geom .Pro- new Scale a P'S Datrox’s 2 oul a Pg { 
ress ion of | of Tem- z| 23 Samal es 3 2 | 28 
Elasticity. | perat. = On y- a i Of 
227inch,| 2020 | 1999 | 93.1 in. 61 | g2e| 32° | 581 | 
30.0 212 212 | 300 9°16 | 52| 466 | 8-67 
39 5 eee 225 | 3911 13°77 | 72 | 62°55) 12:60 | 
520 | 232 | 2386! 503 20.65 | 92 | 79-84! 18-40 | 
69:0 242 | 252:6| 64:5 | 310 {112 | 98°50} 27-2 | 
910 |. 252 2668 | 81:5 46°54 |132 |118:50] 97-7 
120-0 | 262 281-2 |103°5 6988 |152 |139.9 | 56:8 
158 Q72 =96:2 |131 7 10491 |172 |162-4 | 83-3 
208 | 282 311-5 |164°8 1575. |192 |186-5 1118-3 
: 2365 |212 |212- 1169-0 
The numbers of the first and fourth column ought evidently 
to agree, if the theory be just. Their differences, on the con- 
trary, are prodigiously great. At 272° of his scale, for example, 
equal to 2962 of ours, the law of progression makes the elastic 
force of aqueous vapour amount to 158 inches: experiment 
gives 131-7; and I am confident, that the latter cannot be in 
error above an inch or two. Again at 262°, equivalent to 281°-2 
Fahrenheit, his theory gives the force of the same vapour at 120 
inches ; by observation it is only 103°5. Now at this part of the 
scale, my result is confirmed by the concurrence of those obtained 
by Betancourt and Robison. T consider this demonstration com- 
plete. If we compare these very elasticities of Mr, Dalton, with 
the table formerly given by the same philosopher *, we shall find 
discordances which no ingenuity can harmonize. "At that time, 
225° of Fahr.=222° of the new scale, gave a force of vapour 
equal to 38°3; it is now 39°5 . 252°°6 F. = 242° D. then co- 
incided with an elasticity of 58-6 inches; above, it is 69. And 
finally, 281°:2, F.=262° D. were opposite to 90 inches; they 
have become here 120, And yet no new, experiments on the 
vapour of water have been adduced, to justify such immense al- 
terations. 
It may be said, situate that these changes arise merely from 
the substitution of one hypothesis for another ; but the deviations 
from experiment are even more remarkable, since as 282° new 
scale, correspond to 311°*5 Fahr., the difference amounts to 43 
inches, being more than one-fourth of the total elastic force ge- 
nerated at that high temperature. 
* Manchester Memoirs, vol. v. 
G3 When 
