THE SPECIFIC HEAT OF BODIES. 567 
changed places in the vessels of water. In this 
way the effect of any slight difference in the capa- 
city for heat of the vessels will be eliminated. 
The next step will be to determine the capacity 
for heat of the vessels which are to be employed 
in the experiments. These vessels ought to be 
as thin as possible, in order that their capacity for 
heat may be very small in comparison with that 
of their contents. They may be constructed of 
any material incapable of being acted upon by 
the liquids. In order to ascertain the capacity 
for heat of these vessels, one of them must be 
filled with water, and the other partly with water 
and partly with the material of which the vessels 
are made. A platinum wire, whose resistance 
or heating power is already known, must be 
placed in each vessel, and then made to form 
part of the circuit of a voltaic battery, so that the 
same current shall traverse both wires. The 
resistances of the wires and the increase of the 
temperatures will then determine the relative 
capacities of the vessels and their contents, from 
which the specific heat of the material of which 
the vessels are made may be readily deduced. 
For calling the quantity of water in the first 
