122 Mr. Grove on the Effect of 



difference in the arcs of deflection of the needle at the instant 

 of meeting or breaking contact, whether the wires were in 

 atmospheres of hydrogen or of atmospheric air; nor when 

 parallel platinum wires with their surrounding atmospheres of 

 gas were immersed in a given quantity of water, could I detect 

 any difference in the resulting heat, whether the current passed 

 in the same or in a different direction through each wire. 



My next object was to ascertain whether, in cases of ordi- 

 nary ignition, the same apparent annihilation of lieat took 

 place in hydrogen gas as with voltaic ignition. Two iron 

 cylinders AB, fig. 4<, each weighing 390 grains, were attached 

 to long iron wires bent back Fig. 4. 



in the form shown in the 

 figure. The cylinders were 

 placed together in a crucible 

 of fine sand, and the whole 

 heated to a uniform white 

 heat. The cylinders were 

 now taken out of the sand, 

 placed atthe surface of equal 

 portions of water in the ves- 

 sels C and D ; two inverted 

 tubes, e^f the one of hy- 

 drogen, the other of atmo- 

 spheric air, were placed over 

 them, and the whole quickly immersed in the water, and re- 

 tained by a little contrivance, which I need not particularize, 

 in the position shown in the figure. The temperature of the 

 water at the commencement of the experiment was 60° Fahr. 

 In four minutes the water surrounding the hydrogen had risen 

 to 94;°, and became stationary there, while that surrounding 

 the air had only reached 87°; in ten minutes the water sur- 

 rounding the hydrogen had sunk to 92°*5, while that sur- 

 rounding the air had risen to 93°, which was the highest tem- 

 perature it reached ; thus the respective maxima were 94° and 

 93°; but considering the greater time which the water sur- 

 rounding the air required to attain its maximum temperature, 

 and that being during this time at a temperature above that 

 of the surrounding atmosphere, it must have lost something of 

 its acquired heat, we may fairly consider the maxima to be the 

 same, and that the difference of effect in the two gases had 

 reference solely to the time occupied in the transference of the 

 heat. In a second experiment the results were similar, the 

 maximum being in this experiment 92'5 in hydrogen, and 91 

 in air*. 



* Iron wire produces a similar effect to platinum wire in the voltaic ox- 

 peiiments. 



6 



