110 
DRS. W. RAMSAY AMD S. YOUNG ON SOME OF 
Temperature. 
Volume of 
1 grm. 
Pressures of 
mercury. 
Temperature. 
Volume of 
1 grm. 
Pressures of 
mercury. 
cub. centims. 
millims. 
cub. centims. 
millims. 
190 
11412 
9,837 
230 
1-2122 
21,085 
1T408 
12,813 
1-2101 
31.745 
1T386 
30,029 
1-2079 
42,249 
1Y365 
39,904 
240 
1-2319 
25,276 
200 
1T567 
15,014 
1-2300 
32,452 
1T559 
18,695 
1-2282 
41,614 
1Y538 
30,513 
1T516 
43,901 
250 
1-2516 
30,059 
1-2508 
36,040 
210 
1T734 
14,404 
1-2490 
43,925 
IT 732 
17,488 
1T710 
31,467 
260 
1-2750 
35,028 
1T689 
43,405 
1-2735 
40,210 
220 
1-1915 
17,622 
1-1905 
27,251 
1-1884 
39,432 
II. Vapour-pressures. 
The pressures of the vapour were read from experiments with a larger quantity of 
water in the tube, as well as when the quantity was small ; but uniform results were 
not obtained. The vapour-pressure of water, unlike that of other liquids, depends to 
some extent on the amount of substance present.'" This is to be attributed to the 
fact, that with only a small amount of liquid present, a relatively large surface of the 
tube is exposed to the vapour, and, as there can be no doubt that the vapour adheres 
to the surface, the pressure is lowered to a certain extent. The results, with the 
larger quantity, are therefore given as probably more correct. Each pressure is the 
mean of some seven or eight readings in which the relative volumes of water and 
steam were altered within the greatest limits which the tube allowed. 
The pressures are, as before stated, corrected for deviations from Boyle’s law. 
To facilitate comparison, the results obtained by Regnault and others are placed 
in juxtaposition with ours ; and also columns showing the differences between our 
results and those obtained in other ways. The columns are distinguished as fol¬ 
lows :— 
“ R. and Y. ” stands for Ramsay and Yoitng. 
“ Reg. curve” stands for Regnault’s copper-plate curves, given in the ‘ Memoires 
de l’Academie,’ vol. 26 . 
“ Reg. H.” and “Reg. F.” signify Regnault’s results calculated by Biot’s formula, 
log p — a + baf + c/T, using the constants marked H and F respectively. 
“ Reg K. ” signifies Regnault’s formula K, viz., p — aa* l{l + rnx) 
* See Appendix, pp. 120 and 121. 
