M. E. Wiedemann on the Specific Heats of Gases. 83 



tiras. in length, furnished with a funnel-shaped protuberance, 

 P. In this box is placed the thin-walled copper cylinder, Gr, 

 which has a length of 11 centims. and a diameter of 4 centims., 

 and is filled with fine copper gauze. The gas enters by m n 

 and departs by op. The latter tube is made of copper so far 

 as 5, from s to p it consists of G-erman silver : it is 17 millims. 

 in length. It was found that too much heat was conducted 

 from the warming-vessel to the calorimeter if the exit-tube 

 was made entirely of copper ; the correction-constant, k (to 

 be discussed hereafter), received therefore too high a value. 

 A thermometer passes through the lid of the heating-vessel. 

 The liquid in the warming-vessel is constantly kept in motion 

 by means of a stirrer, which consists of two perforated hori- 

 zontal plates hard-soldered to a stirrup Y, and at a distance 

 from one another somewhat greater than the breadth of the 

 copper cylinder. A cord passing from V over a pulley is con- 

 nected with clockwork, whereby the stirrer is raised twenty times 

 per minute ; it falls again by its own weight. By an arrange- 

 ment of sockets any liquid which might be carried up with 

 the stirrer finds its way back into the warming-vessel. The 

 temperature of the water (or paraffin) was regulated so that 

 it did not vary more than, at the utmost, 1° during the 

 experiments. 



The calorimeter (k) consists of a silver vessel, outwardly of a 

 cylindrical shape, 5J centims. in height and 42 millims. in 

 width, the thickness of the walls being Oo5 millim. Three 

 vertical silver tubes, bound together by little horizontal tubes, 

 are fused into the calorimeter ; these serve for receiving the 

 heat given up by the gas under examination. The gas enters 

 through the tube /3 placed horizontally 8*5 millims. from the 

 bottom of the cylinder (this tube is 8 millims. in breadth) ; 

 thence it pases to the first vertical tube, from the upper end 

 of which it is conveyed to the next tube, and so on, finally 

 making its exit by the narrow tube (2\ millims. wide) q. 

 The individual tubes are 9 millims. in breadth and 41 millims. 

 in height ; they are all filled with silver gauze. Through a 

 lid placed on the top of the vessel pass a thermometer, the 

 stirrer, and the tube q. The bulb of the thermometer is placed 

 between the first and third tube, the stirrer between the second 

 and third. 



Fig. A represents a section of the calorimeter at the level of 

 the entering tube, ft is the tube by which the gas enters ; a, b> 

 and c are the first, second, and third silver tubes respectively ; 

 t is the thermometer, and r is the stirrer. A small quantity 

 of grease is introduced between the rim of the lid and the 

 vessel to prevent the escape of the water which mav be raised 



G2 



