570 ON A NEW METHOD FOR ASCERTAINING 
the platinum wire, a column of mercury, inclosed 
in a glass tube of narrow bore, may be chosen as 
the conducting medium. 
2.—Method with Solids. If the solid body be 
insoluble in water, it must be broken into small 
pieces, and placed in the experimental vessel, the 
remainder of which must then be filled with pure 
water. In this case, as well as in the last, equation 
6 applies; the only difference being that the quanti- 
ty a' includes the water in the experimental vessel, 
as well as the vessel itself, considered as water. 
Soluble bodies must be inclosed in small tubes 
or bottles, made of tinned iron, platinum, or glass, 
whose capacity for heat has been previously 
determined. The bottles must be completely 
immersed in the water contained in the experi- 
mental vessel. It will be necessary, in this case, 
to take care to let sufficient time elapse between 
the stoppage of the current and the determina- 
tion of the temperature, in order to allow the 
salt to acquire the temperature of the water. 
Equation 6 applies in this case also, the quantity 
a‘ including, as in every other case, all the bodies 
in the experimental vessel, whose capacities are 
known, considered as water. 
