DETERMINATION OF THE SPECIFIC HEAT OF WATER. 425 
wire were fixed to stout copper wire about 5 centims. long wedged into the bottom of 
cylindrical pieces of ebonite. The ebonite was held in position by brass supports 
soldered to the frame. The upper ends of the copper terminals projected into the 
bottom of cups drilled from above in the ebonite; these holes, which were 9 millims. 
wide and 15 millims. deep, were filled with mercury, and served to connect the coil 
Fig. 4. 



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with the outer circuit. ‘The coil was insulated by a covering of shellac. ‘To obtain a 
thin and uniform layer, the frame was immersed in a weak alcoholic solution of the 
substance, and afterwards heated for half-an-hour in an air-bath at a temperature of 
130° C. This process of immersion and heating was repeated until the insulation 
resistance was higher than that required by the conditions of the experiment, and we 
MDCCCXCV.— A. 31 
