RECENT PROGRESS IN PHYSICS. 411 



A, the leaves of the electroscope h fell only to 2^ lines. Hence there 

 was no conducting connexion between B and the lamp, and the 

 charging of B took place in the way indicated above. 



If B was electrified, and while the lamp burned, A was touched, 

 the electroscope collapsed slowly, stood at 3 lines divergence, and 

 even after two minutes the divergence was 2^ lines. B being held 

 horizontally over A, the steam of the lamp struck B ; consequently a 

 conducting connexion existed between A and B. In this case, when 

 the experiments just described were repeated, the electroscope h at 

 once collapsed when A was touched. 



From the results of these experiments, it appeared that the effective 

 steam points extended far beyond the flame and the metallic cylinder 

 surrounding the lamp, otherwise the cylinder would have destroyed 

 the action of the points,, as, in fact, is the case with incandescent 

 bodies. 



When burning spunk was laid upon A, and B properly insulated, 

 was held horizontally over A, A being electrified by contact with one 

 of the poles of a dry pile, the electroscope h immediately diverged ; 

 but this did not happen when the burning spunk was surrounded 

 by a metallic cylinder 13 lines high by 9 in diameter. This shows 

 that the ascending smoke in this case was not a conductor. The 

 action of incandescent bodies, therefore, is not^ like that of flame, 

 produced by steam. At the place where the mass burned, a hole was 

 formed whose edges were prevented from burning by the carbonic 

 acid, &c., produced. Where a number of such holes came together, 

 a projection of unburnt mass remained. By continued burning, these 

 projections became pointed ; and to these points, standing out every- 

 where over the burning body^ all the consequences are applicable 

 which were developed above for the steam points. 



Slow match, pastiles, &c., behaved like glowing spunk. 



Biess modified these experiments in various ways, and always ob- 

 tained results confirmatory of his theoretical views. In all these ex- 

 periments the combustion of the ignited bodies was made as perfect as 

 possible. Spunk and charcoal pastiles (made like ordinary fumi- 

 gating pastiles) were kept burning by constant blowing, and cleared 

 of ashes ; and the spirit-lamp used only for intense ignition. By 

 such precaution, every disturbance of the described effects was avoided. 

 When, on the contrary, the ignition of the body under examination is 

 not perfect, an experiment with one of the kinds of electricity is found 

 to succeed often much more easily, and in a more striking manner, 

 than with the other, Avhich is not the case in perfect ignition. 



The disk A was placed in a vertical position, andB parallel to it, 

 and then on A was fastened a pastile, (a small cone made of pulver- 

 ized charcoal and some saltpetre, mixed with gum tiagacanth,) which 

 was directed towards B. When the pastile was ignited over half of 

 its surface, and covered with ashes, A was touched with one of the 

 poles of a dry pile. If it was the positive pole, the electroscope h 

 diverged very slowly, and at most only 2 lines ; but if the negative 

 pole of the dry pile was applied to A, the electroscope diverged quickly, 

 and more than 5 lines. On the other hand, an electroscope connected 

 with the pastile and the plate A diverged more rapidly, and to a 



