. 
1817.] Dilatation of Liquids at all Temperatures. 437 
become greater, and the error committed by neglecting 3 c'T? more 
sensible. 
I shall apply this result to the experiments made by Mr. Dalton 
on the apparent maximum condensation of water in dilatable vessels. 
The experiments are as follows.* I have joined to them the cubic 
dilatation of the vessels employed :— ‘ 
eee 
Cubic dilatation ofMax. condensation} Degrees at which 
Vessels, ditto for 1°  jobserved in degrees|water is equally 
Reaumur. of Reaumur. dilated. 
ee ee ey 
Plint glass......} 0°00003003 4°222° 0 and 8-444? 
Tron ..........| 0°00004578 4°667 9°334 
Copper ........| 0°00006309 6°000 12-000 
Brass ..... «e+e! 0°00007002 6°222 12°444 
Pewter ........| 0:00007266 6°664 13°328 
Lead ..........] 000010689 7778 15°555 
—————— a 
The following table exhibits a comparison of these results with 
our formula :— 
_— ee 
Apparent maximum in degrees of 
Vessels, Reaumur, 
Calculated. | Observed. | Difference. 
Flint glass} 4°236 4:222 | —0°014 
Tron ....| 5°072 4667 —0°405 
Copper..| 5°960 6000 | +0040 
Brass ...] 6°319 6°222 | —0:097 
Pewter ..| 6°456 6°664 +0°108 
Lead ...| 8246 | 7778 | —0-468 
The differences existing between calculation and experiment are 
very slight. ‘They may depend upon some slight difference between 
the dilatability of the substances examined by Lavoisier and La- 
place, and those employed by Mr. Dalton in his experiments. This 
is the more likely, because errors in the dilatation are very much 
increased by the smallness of the divisor with which they are 
affected in the expression of T; but as the slight deviations are 
generally negative, [ am disposed to suspect that the water employed 
by Mr. Dalton, at least in some of his experiments, was not quite 
pure, but contained a small quantity of salt, which sank a little its 
maximum of condensation. ‘This explains why, in making use of 
vessels the dilatation of which was almost insensible as stone ware, 
Mr. Dalton found the apparent maximum lower than the ordinary 
* Nicholson’s Journal, x, 93, 
5 
dD 
