the Elements Carbon, Boron, and Silicon. 173 



Two platinum tubes, closed at their lower ends, 6 centims. in 

 length, 1*2 centim. wide, the walls of the tubes being 1*2 millim. 

 thick, were placed side by side at a distance of 1*2 centim., and 

 held in this position by means of a crosspiece of platinum, from 

 which projected perpendicularly a platinum rod by means of which 

 the two tubes could be moved about at will. 



Two pieces of platinum, of the total weight of 32*39grms.,were 

 brought into one of the tubes ; and in the other such a quantity 

 of the substance under examination was placed as would have a 

 heat- value nearly equal to that of the 32*39 grms. of platinum. 

 The tubes were closed by asbestos stoppers, and placed in a small 

 muffle made of sheet copper about 2 millims. thick, which was 

 entirely closed and then placed at the back of the muffle of a 

 newly constructed gas muffle-furnace, in which any temperature 

 between 500° and 1000° could easily be obtained. From the 

 arrangement and position of the tubes it might with safety be 

 assumed that after the expiry of a sufficient time the contents of 

 both would be at the same temperature. When the tubes had 

 remained in the furnace for an hour, the perpendicular platinum 

 rod was seized by a pair of very hot tongs and the tubes very 

 quickly transported to a double water-calorimeter standing as 

 close by as possible. At the proper moment, while the tubes were 

 held in the operator's right hand, the asbestos stoppers were 

 withdrawn simultaneously by the left hand, and the contents of 

 the two tubes thrown, by a jerk of the right hand, the platinum 

 into one, the carbon into the other calorimeter. After a little 

 practice the time which elapsed from the withdrawal of the hot 

 tubes from the furnace until the moment when the contents of 

 the tubes found themselves in the calorimeter was reduced to 3 

 or at the most 4 seconds. The loss of heat during this brief 

 time affected both tubes in an exactly similar manner, inasmuch 

 as the tubes, in respect of size, shape, material, and temperature, 

 were exact counterparts of one another. Considering the brief- 

 ness of the time and also the thickness of the walls of the plati- 

 num tubes, the reduction in the temperature of the enclosed 

 substances must have been extremely small. Inasmuch as the 

 weights of the two substances were equalized so that the product 

 of the weight into the specific heat was the same for each, the 

 small reduction of temperature might be taken as the same in 

 each case. Against the assumption that the temperature of the 

 platinum was the same as that of the substance under examina- 

 tion at the moment when they both fell into the calorimeter, no 

 argument of importance can be urged. 



The double calorimeter employed consisted of two identical 

 vessels of the thinnest sheet copper placed parallel to one another 

 at a distance of 2 millims. The cover of each instrument had 



