612 DE. A. DITPEE AND F. J. M. PAGE ON THE SPECIFIC HEAT AND OTHEE 
Table XIV. 
Percentage of alcohol, 
by weight. 
1. 
Theoretical specific 
heat (Table VII.). 
Units of heat divided 
by 3-411. 
3. 
Specific heat thus 
calculated by adding 
columns 2 and 3. 
Specific heat found 
by experiment. 
10 
96-043 
7-823 
103-866 
103-576 
20 
92-086 
12-885 
104-971 
104-362 
30 
88-129 
14-060 
102-189 
102-620 
40 
84-172 
13-152 
97-324 
96-805 
45 
82-193 
11-377 
93-570 
94-192 
50 
80-215 
10-432 
90-647 
90-633 
60 
76-258 
7-992 
84-250 
84-332 
70 
72-301 
5-517 
77-818 
78-445 
80 
68-344 
3-658 
72-002 
71-690 
90 
64-387 
2-258 
66-645 
65-764 
In subclass b a somewhat similar relation exists between the boiling-points and capil- 
lary attraction. Mixtures having the same depression of boiling-point have also the 
same depression of capillarity below that calculated ; and the depression of the boiling- 
point may be obtained by dividing the depression of capillarity, when water rises to 100 
millims., by 3-410 (Tables IX. & X. and Plate LXIV.) ; or the curve giving the depression 
observed in capillarity will be nearly the same as that giving the depression of the 
boiling-point, if water be taken as rising to 29‘3 millims. The numbers, however, thus 
obtained do not agree quite so closely as do those obtained in a similar manner with 
the specific heat and heat produced by mixing ; but it must be remembered that the 
boiling-point cannot be estimated with the same amount of accuracy as the specific heat, 
whilst it also varies with the height of the barometer, and the capillary attraction with 
the temperature. It might thus be possible to select a temperature and pressure in 
which the relation between the two properties would be as perfect as that existing 
between the specific heat and the heat produced by mixing. 
In Class II. subclass c (see Table XII. Plate LXIV.), the rate of expansion, is remark- 
able, inasmuch as the first addition of alcohol, up to nearly 20 per cent., causes the rate 
of expansion to be below that calculated, whilst in all the rest of the mixtures the rate 
of expansion remains constantly above that calculated; and so a mixture about 17 or 18 
per cent, has a rate of expansion identical with its theoretical expansion. 
In subclass cl it will be noticed (Table XIII. Plate LXIV.) that the first additions of 
alcohol, although the latter is much more compressible than water, produce mixtures 
which are less compressible than water, so that a mixture between 45 and 50 per cent, 
has the same compressibility as water. 
Other characters, which have been examined by previous experimenters, are : — 
1. Vapour-Tension . — This falls under Class I. subclass b, reaching a maximum devi- 
ation below the mean, calculated in a similar way, at 30 per cent, of alcohol, according 
to the researches of Dronke, ‘ Ueber die Spannkraft der Dampfe aus Fliissigkeits- 
gemischen. Inaugural-Dissertation, Marburgl862; and Wullner, Pogg. Ann. cxxix. 353. 
2. Specific Gravity ; and 3. Index of Refraction . — The two latter form a new class. 
