on some of the leading Doctrines of Caloric, &c.. 191 
It deserves to be remarked, that my experiments on the re- 
lative times of cooling a globe of glass, successively filled with 
water, oil of vitriol, common oil, &c. give exactly the same results 
as Mr. Dalton derived from mixtures of two ounces of ice and 
sixty of water. This concurrence is the more satisfactory, since, 
when the Essay on hydrochloric acid was written, I had no re- 
collection of Mr. Dalton’s experiments. I found that from 210° 
to 150° the specific heat of oil bears to that of water the ratio of. 
597 to 1000; and from 150° to 90°, that of 513 to 1000. Now, 
at his highest and middle temperatures of 200° and 120°, which 
come nearest to mine of 180° and-120°, we have. by him. the 
ratio of 176°°5 to 150°. 
- But 597 :513:: 176: 150 exactly, which is a very striking 
coincidence, and affords the happiest confirmation of the accu- 
racy of both sets of experiments, as well as of the justness of the 
principles on which they were conducted, and on which, parti- 
cularly, my reductions were founded. We now see the reason 
why, when equal weights of water at, 32° and 212° are mixed, 
the temperature may be lelow the mean, as was found by De 
Luc. The capacity at the middle temperature is. greater than 
the mean capacity of the two extremes, (that is of the ingredients 
mixed, ice, cold and boiling water,) and therefore the thermo- 
metric tension will be lessened, and its mercury will, descend on 
the scale*. This diminution of temperature will cause a cor- 
responding diminution of bulk, which affords a complete answer 
to Mr. Dalton’s first and only plausible argument, formerly 
quoted against Dr. Crawford’s deductions, and the opinions of. 
DeLuc. With regard, however, to these experiments, of mixing 
hot and cold water to find a mean temperature, there are sufficient 
difficulties to render the result uncertain to two or three degrees. 
Hence, nothing of moment can safely be inferred from them. 
Concerning sulphuric acid in its various states of dilution, I 
beg to refer the reader to my Essay on the subject, where he will 
find several peculiarities relative to its volume at different acid 
strengths, that entirely change its relations to caloric. I have 
not seen these formerly adverted to by any chemist. They were 
evidently unknown to Mr, Dalton. 
Cuapter III. 
On the latent Heat of different Vapours. 
What relation is there between the caloric existing in the va- 
pours of different substances, and the temperatures at which they 
respectively acquire the same elastic force ? 
* Laking Mr. Dalton’s three numbers as correct: then 
= 
176°5 +198 
porters 
152°°25. But 150° in the middle are equal to the former mean of the two, 
Hence, the proposition in the text is demonstrated, 
On 
