414 RECENT PROGRESS IN PHYSICS. 



described inductive action, and may easily effect the greater part of 

 the charging and discharging. 



Fetrina has endeavored to explain the electrical effect of flame in 

 a very peculiar manner, (Pog. Ann. LYI, 459.) He thinks that the 

 oxygen rushing toward the flame enters into chemical combination 

 only under a definite electrical condition, and he supposes that this 

 condition continues to a considerable distance from the place of com- 

 bination. 



Fetrina has not yet established this hypothesis. 



SECTION THIRD. 



the leyden jar and effects of the discharge. 



§28. Abria on some of the mechanical phenomena accompanying 

 ELECTRICAL DISCHARGE. — When the discharge of a Leyden jar is passed 

 between points, and a glass plate, strewed over with a fine powder, is 

 placed beneath the path of the spark, after a few discharges the pow- 

 der is observed to be arranged in curves with some regularity. 



Abria first observed and described this phenomena, (Ann. de Chim. 

 et de Phys., LXXIV, 186 ; Pog. Ann. LIII, 589.) A clear concep- 

 tion cannot be obtained from his memoir of what kind of curves these 

 are, and this is chiefly due to the fact that the figure, which should 

 serve for the purpose of explaining the matter, does not correspond at 

 ail to the text. Even after having myself become acquainted with the 

 phenomenon by experiment, the figure attached to the memoir is still 

 incomprehensible. 



In order to investigate tho subject I made the experiment in the 

 following manner : The interior coating of a jar was connected with 

 the conductor of the machine. In the path which the electricity had 

 to traverse from the interior coating to the exterior, Henley's universal 

 discharger was placed. A glass plate was laid on its stand, thinly 

 sprinkled with minium or with flour of sulphur. The result was the 

 same for both powders ; the particles arranged themselves as shown 

 in figure 46. 



Fig. 46. 



The two points between which the 

 sparks passed are represented by a 

 and h; beneath them is the plate 

 c d e, on which the regularly strew- 

 ed powder arranged itself after re- 

 peated discharges, in the manner 

 represented by the curved lines. 



The curves are modified, of course, 

 when the distance of the plate from 

 the line of the points a and h is 

 changed. They are not continuous, but composed of short broken por- 

 tions, as shown in the figure, and I cannot, therefore, comprehend how 



