954 
DR. J. JOLY ON THE SPECIFIC HEATS 
Referring to Part T., for a general account of the corrections to be applied to these 
experiments, it is only necessary to recall here sufficient to explain the contents of 
the last table. In calculating the correction due to the effect of the thermal increase 
of volume of the vessel upon the contained gas several quantities have first to be 
deduced. The equation for the work done by the gas is 
£ = !P,Vi^fe - ',)] {1 + (« - /8) i ((, - h)]. 
The amount of this correction, expressed as a weight of steam precipitated upon 
the vessel, is to be deducted from the observed weight of precipitation. This sub¬ 
tractive quantity is given in the column headed Cor. I. of the table, the corrections 
being numbered in accordance witli Part I. It is based upon the numbers contained 
in the previous column. The second column contains the initial volume of the sphere 
corrected for temperature only, on a coefficient of thermal expansion (/3) of O'OOOOS. 
The third column contains an approximate estimate of the pressure P;^, in atmo¬ 
spheres, due to the weight, W, of gas in the vessel at the initial temperature, C- 
In tlie fourth column the effect of the pressure upon the volume of the vessel is 
recorded, basing calculations upon the elastic yielding of the vessel experimentally 
found, as above. An estimate of the jmessure, Po, at the steam temperature is given 
in the fiftli column, and the distending effect of this in the sixth. The manner of 
estimating the pressures is described later. The quantitiy, a, is given in the seventh 
column. It is calculated on the equation 
a 
V — P 
(/g — q) Pj 
By use of the second and sixth columns, and the third reduced to denies. Cor. I. is 
calculated. 
Correction II. deals with the elastic distension of the vessel and the effect of this 
in producing thermal effects on the co)'itained gas. For this, the work 
V = PiTi log e 
or, in grammes of water. 
(PPh) {(log Y^-logAh) (2-30)} 
22500 
the second, third, and seventh columns being used. Except in the case of the first 
experiment, however, this turns out to be a negligible correction. 
The column headed correction VII. contains the additive Correction obtained upon 
reducing the weight of precipitated water to vacuo. The other corrections treated 
of in Part I. are found to be negligible for these experiments, excepting, of course, 
that arising from the unequal thermal capacity of the two spheres. Thus, the 
correction for buoyancy due to distension of the sphere, while in the steam, numbered 
4 in Pat t I., affords but 0'02 of a milligramme in the most extreme case, and the others 
