THE FORMS OF ENERGY. 125 



Absolute Rowland's Values Corrected ergs 



Temperature in ergs and in degrees on 



above C. absolute degrees. hydrogen scale. 



16 4-187 4-186 



17 4-185 4-185 



18 4-183 4-184 



19 4-181 4-182 



20 4-179 4-181 



21 4-177 4-180 



22 4-176 4-179 



23 4-175 4-178 



24 4-174 4-177 



25 4-173 4176 



26 4-172 4-176 



27 4-171 4-175 



28 4-171 4-175 



29 4-170 4-174 



30 4-171 4-174 



31 4-171 4-174 



32 4-171 4-174 



33 4-172 4-174 



34 4-172 4174 



35 4-173 4-175 



36 4-173 4-175 



These values bring out very clearly that there is a variation in the 

 work required to raise 1 gramme of water 1 at different parts of the 

 scale in other words, that there is a variation in the specific heat of 

 water with temperature. They also point to the existence of a minimum 

 value in the neighbourhood of 30. Rowland's work was the first to 

 indicate the minimum value, and his conclusion has since been con- 

 firmed by others. 



Miculescu's Experiment. In 1892 Miculescu presented to the Paris 

 Faculty of Sciences a thesis, in which he gave an account of a water- 

 friction experiment carried out on new lines. The stirring power was 

 supplied by a 1 h.-p. electric motor which was balanced on knife edges 

 in the horizontal line of the axis of the armature. The spindle of the 

 armature was prolonged through a stuffing-box into the water-stirring 

 vessel, where the paddles were attached to it. The couple exerted on 

 the water was measured by hanging a weight on to a horizontal arm 

 projecting at right angles to the axis of suspension of the motor sufficient 

 to keep the motor from turning round. The water in the stirring-vessel 

 was kept at a constant temperature by circulating round the outside of 

 it a current of colder water passing at such a rate that it took heat from 

 the calorimeter as fast as it was developed by the stirring. The heat 

 was measured by the quantity of cooling water sent round and the 

 difference of temperatures of entrance and exit. This difference was 

 measured by a theirnocouple which was graduated in terms of a Tonnelot 

 thermometer, and ultimately in terms of the hydrogen scale. The tem- 

 perature of the water varied between 10 and 13. We may take the 

 result as making 4-187 x 10 7 ergs equivalent to the heat required to raise 

 1 gramme of water at 11 -5 through 1 on the hydrogen scale. 



