[WALKER & HENDERSON] SPECIFIC HEATS OF ORGANIC LIQUIDS 107 
an associated liquid. Aniline is unassociated, and yet when mixed 
with an equal volume of benzene, the temperature falls 3:3°. A still 
more surprising result was obtained with rhigoline B.P. 30°—40° which 
is almost pure pentane and from analogy unassociated. When mixed 
with an equal volume of benzene there was a fall of 4° in temperature. 
Gasoline B.P. 70°—80° gave a similar result with benzene, and with 
the unassociated acetic ether as great a depression as with the associated 
acetone, viz., 5°. It was thought that a determination of the mole- 
cular weight might throw some light upon the results, but a deter- 
mination by the freezing point method gave 73 as the molecular weight 
of rhigoline in benzene, instead of 72, the theoretical value for pen- 
tane. 
Quantitative. In determining with any degree of accuracy the 
heat change during solution it is, of course, necessary to know the 
specific heat of the resulting solution. The latter cannot be taken 
as a mean of that of the two constituents. For this purpose an 
electrical method was adopted, a certain very constant current sent 
through a small incandescent lamp, which was entirely immersed in 
the liquid contained in a silver vessel, serving as the source of heat. 
The lamp was 16 c.p. at 50 volts, and had, instead of a metal socket, 
a glass tube fused on the end through which the copper leads passed. 
The current was measured. by a Weston ammeter and voltmeter, and 
could be read in each case to at least 1 part in 500. The thermometer 
employed was of thin glass with a long, narrow bulb and an enclosed 
milk-glass scale. It was graduated in 7/,,ths of a degree, and could 
be read with accuracy by means of a lens to 0-015°. The calorimeter 
was provided with a well-fitting lid in which were holes for the 
various accessories. It was arranged otherwise as described by 
Ostwald in his Hand und Hilfsbuch. The stirring was done by hand, 
two thin platinum wires passing through the lid serving to raise and 
lower the stirrer. The same volume of liquid was used in every 
experiment. The method seems at first sight to have several grave 
sources of error, and it is doubtless not one of extreme accuracy, but 
as the experiments were all made under the same conditions, and 
are all relative to the specific heat of water which is taken as unity 
most of these errors ought to have been eliminated. The results 
obtained are, of course, the best test of efficiency. In the following 
determinations of the water value of the calorimeter the bath was 
very nearly 16°, and the heating was applied from a few degrees below 
to an equal amount above that temperature. 
Toran Loss OF CALORIES PER DEGREE. 
NOIRE CAE 40 CALE Re DU Ge ZIAD PV HIN On ARR sk te be ot hag RUE ata -2e 21°3 
