9G4 
DR. J. JOLY ON THE SPECIFIC HEATS 
Into the condenser. The condenser was found to act so perfectly that when a loose 
cork was placed closing the inner tube of copper, and there was no leak at the flanges 
of the calorimeter, the circulation of ether, acetone, or alcohol could be continued for 
hours with little attention and with so little loss of the material as to preserve the 
room almost free of odour. My arrangements did not attain to this state of 
perfection, however, till some costly experience had been acquired.. As application 
of a burner directly beneath the boiler containing ether, acetone or alcohol, would 
have been attended with much risk, the arrangement was adopted of heating it by a 
current of steam derived from a small subsidiary steam boiler placed some 2 metres 
distant. This was found to be a very simple and manageable arrangement. The 
steam boiler had. a small valve which could be set so that the steam could be let 
escape more or less directly into the air, a tube sloped upwards from the boiler to 
the vaporizer beneath the calorimeter, entering at the remote end of the heating 
tube (or “ furnace ”) in the figure. The near end was narrowed by a glass tube in a 
cork, bent downward. It was possible to regulate the supply of steam so that a bead 
of water in this tube remained pulsating for two or more hours without being com¬ 
pletely displaced, and once started, the whole system of circulating steam and vapour 
required but little attention. T had, however, many vexatious failures from leakage 
into the inner chamber, which for long I naturally attributed to bad flange joints, till 
ultimately I traced it to a small leak in the soldering of one of the central tubes. I 
may observe indeed, that the presence of a small quantity of vapour within, whether 
ether, acetone or alcohol, seemed to have little or no eftect as a cause of error. As the 
result of my entire experience, however, with this mode of heating, I think a water 
jacket and thermostatic arrangement would probably give less trouble and certainly 
entail less expense. It would in this case only be necessary to provide sufiiciently 
large valves in the bottom of the outer drum to permit of the rapid removal of the 
water immediately before or after the admission of steam. 
The switch and electrical connection permitting of the heating of the orifices for 
the suspending wires during experiment, are seen in the figure as well as the 
platinum spirals (hardly distinguishable in the figure) and forceps holding them. 
The balance above is a sliort-beam (14 cms.) of Sartorius, and weighs accurately to 
-j-Q milligramme when carrying the spheres. The mode of suspension of the spheres 
from the balance is as described in the ‘ Proc. Roy. Soc.,’ loc. cit. 
Four intervals of temperature were adopted for the experiments : air temperature 
to 100°; 35° (B.P. of ether) to 100°; 56° (B.P. of acetone) to 100°; and 78° (B.P.. of 
alcohol) to 100°. The procedure was as follows in making the experiments. A 
certain weight of carbon dioxide being enclosed within tlie sphere, this is hung on 
the calorimeter; both outer and inner drums closed, and after some hours the air 
temperature in the calorimeter and the barometric pressure determined. The 
equilibration of the balance is now attended to and particulars noted down. Steam 
from the small boiler is then led into the steam ‘ furnace ’ of the evaporator, in which 
