174 
DR. H. T. BARNES ON THE CAPACITY FOR HEAT OF WATER 
Each of the two mica plates was serrated on the two long edges and two bare 
platinum-silver wires, '4 millim. in diameter, wound on side by side. After winding, 
the ends of the platinum silver wire were fused to copper-wires of the same size in a 
blow-pipe flame. The wires on the frames were then annealed at a low red heat by 
passing a heavy electric current through them. After the two mica plates were 
clamped together so as to include the heavy copper-wires at both ends, the copper- 
wires that were fused to the platinum-silver wires were soldered to the end faces of 
the copper-wires protruding into the space between the mica plates. There being in 
all eight ends to be soldered and four heavy copper-wires to solder into, each large 
copper-wire was connected to two of the small copper-wires fused to the platinum- 
silver wire. Each 1-ohm consisted thus of four bare platinum-silver wires, 16 millims. 
Fig. 5. 
in diameter, in parallel; direct solder joins of platinum-silver with copper were 
avoided, and the mica plates were arranged so as to give the best possible circulation 
when immersed in an oil-bath. 
The paraffin oil-bath was made from a square ebonite box, and included, besides the 
two 1-ohm coils, a stirrer and coil of metal tube for a water circulation, fig. 5. The 
coils always remained fastened in the bath, and when it was necessary the bath, 
including the ohms, could be removed from the position assigned for it in the experi¬ 
ment where the ends of the two inverted U-shaped connections from the coils were 
immersed in mercury-cups in two heavy copper forgings in the calorimeter circuit. 
When a comparison was made on the commutator-bridge, the bath was conveyed to 
the place where the bridge was always kept. During a comparison, the stirrer was 
run by a small electric motor and the temperature of the oil taken by a thermometer 
immersed in the bath. For the determination of the temperature coefficient of the 
