Mr. W. R. Grove on the Eledricitij of the Blowpipe Flame. 49 



The flame-cuiTent proper in my experiments is opposed to, and 

 conquers the therrao-cmTeut. 



On advancing the coil from the root of the flame towards the 

 further coil, the deflection lessens, but still preserves its direction 

 until the wires get very closely appi-oximated, when the deflec- 

 tion of the flame-current yields to that of the thermo-current, 

 and the direction of the needle depends on the relative heat of 

 the coils. 



A wire of zinc near the root of the flame with the platinum 

 coil in the full flame gave a much smaller deflection, only 2° ; 

 when the direction of these wires was reversed, the current was 

 stronger, the galvanometer marking 5° : the direction of the 

 deviation was in both instances the same as with platinum and 

 platinum. 



Iron and copper acted as zinc, but rather more feebly. As 

 in these experiments the wires of zinc, iron, and copper respect- 

 ively were stouter than the platinum wire, I attribute the supe- 

 rior amount of deflection when the oxidable metal was in full 

 flame to the greater cooling effect of the thicker wire reduchig 

 the antagonizing thermic curi'ent. 



As the above experiments seemed to show that there was a 

 proper flame-current irrcs])ective of, and even overcoming the 

 thermic flame-current, I was led to expect that by uniting in 

 direction these two currents I might get more marked results. 

 The following experiment, it will be seen, I'calized this expec- 

 tation. 



I formed a little cone of platinum foil of -i^th.^ of an inch in 

 depth, and the same width at the widest part ; I suspended this 

 in a ring of platinum wire and substituted it for one of the 

 coils. 



Being placed in the full flame, the coil being at the root, it 

 was filled with water, and water dropped into it from a pipette to 

 supply that which was boiled away. I now readily obtained a 

 deflection of 20^ in the same direction as in my original experi- 

 ment, and frequently the needles deviated to 30°. When the 

 cone filled witii water was placed at the root and the coil in the 

 full flame, the deviation was only .5°. 



In all the above exjieriments with the blowpipe it will be seen 

 that the direction of the current vyas, as far as a comparison can 

 be instituted, the reverse of that indicated in the experiments of 

 Ilankel, excepting his experiment with the flame of hydrogen ; 

 and also the reverse of the greater part of the experiments of 

 Buff", which lie rightly attributes to thermo-electricity. 



One result of M. Jiutt' [Archives d'Electricite, vol. xvii. p. 275) 

 when he places one wire in tlie centre and the other at tlic outer 

 margin of the flame, is ])robably dependent on a similar cause to 

 Phil. May. S. 4. Vol. 7. No. 42. Jan. 1H54. E 



