610 DE. A. DUPRE AND F. J. M. PAGE ON THE SPECIFIC HEAT AND OTHER 
Table XII. 
Per cent, of alcohol, 
by weight. 
Volume at 10° C. 
Volume at 20° 0. 
Found. 
Volume at 20° C. 
Calculated. 
Difference. 
0 
100 
100-154 
100-154 
10 
100 
100-212 
100-272 
-0-060 
20 
100 
100-405 
100-386 
+ 0-019 
30 
100 
100-632 
100-489 
+ 0-143 
40 
100 
100-783 
100-601 
+ 0-182 
45 
100 
100-827 
100-652 
+ 0-175 
50 
100 
100-868 
100-700 
+ 0-168 
59-77 
100 
100-914 
100-789 
+ 0-125 
69-70 
100 
100-980 
100-874 
+ 0-106 
79-81 
100 
101-020 
100-954 
+ 0-066 
89-89 
100 
101-052 
101-034 
+ 0-018 
100-00 
100 
101-088 
101-088 
Section VI. — Compressibility. 
The compressibility was estimated in an apparatus similar to the one employed by 
Regnault and Grassi, but of simpler construction. 
The piezometre is a cylindrical glass tube with spherical ends, and has a long capil- 
lary tube attached at one end ; it is about 150 millims. long and 32 millims. in diameter. 
The weight of water contained in it at 4° C. is 114-9727 grms. ; and 1 millimetre of 
the capillary tube has a capacity of 0-000517173 cub. centim. 
Air was forced into the apparatus by means of a small pump, and thus pressure was 
applied simultaneously to the inside and outside of the piezometre; the amount of 
pressure is ascertained by the length of a column of mercury supported by it. The 
compression produced is read off by a millimetre-scale etched on the capillary tube. 
To the compressibilities thus found, 0-000002 was always added as a correction for 
the compressibility of the piezometre, this number being about the mean of the effect 
observed by Grassi when a glass piezometre was employed. 
The numbers in the following Table are calculated for a pressure of one atmosphere. 
Table XIII. 
Weight of water contained in Piezometre at 4° C. 114-9727 grms. 
1 millim. of capillary gauge=0-000517173 cub. centim. 
Per cent, of 
alcohol, by 
weight. 
Depression, 
in 
millims. 
Temperature, 
in degrees 
Centigrade. 
Compression. 
Calculated. 
Difference. 
0 
40-68 
9 
0*00004774 
0-00004774 
10 
36-92 
11-2 
0-00004351 
0-00005387 
-0-00001036 
20 
33-00 
11-5 
0-00003911 
0-00005998 
0-00002087 
30 
32-92 
10-2 
0-00003902 
0-00006584 
0-00002682 
40 
36-88 
9 
0-00004347 
0-00007118 
0-00002771 
45 
39-20 
8 
0-00004608 
0-00007364 
9-00002756 
50 
41-60 
9 
0-00004878 
0-00007600 
0-00002722 
59-77 
48-20 
10 
0-00005620 
0-00008029 
0-00002409 
69-70 
53-25 
10-1 
0-00006159 
0-00008426 
0-00002267 
79*81 
59-96 
9-6 
0-00006942 
0-00008775 
0-00001833 
89-89 
68-76 
11-1 
0-00007950 
0-00009140 
0-00001190 
100-00 
81-36 
9-7 
0-00009349 
0-00009349 
