]54 * EST CONSTRUCTION OF A VOLTAIC APPARATUS. 



means of a fine screw, through a collar of leathers, and the 

 distance between the points was ascertained by a small mi- 

 crometer attached. This receiver was inverted over well 

 , dried potash over mercury, ;md suffered to stand a couple 

 of days, to deprive the air it contained, as thoroughly as 

 possible, of moisture. The 1 250 plates being excjted pre- 

 cisely to the same degree as the great battery, mentioned in 

 the beginning of this communication; and the little receiver 

 Striksr." cIip- placed in the circuit, I ascertained its striking distance to 

 tancs'02 of an be r \ of an inch. That I might be certain, that the air in 

 whites*' ' ' *' ie a PP ara tns had not become a conductor by increase of 

 temperature, I repeated the experiment several times with 

 fresh cool air, and always with the same result; but perhaps 

 it will be objected, that the striking distance was so small, 

 #s not to afford a satisfactory refutation of the argument al- 

 luded to, when it is considered tohow very great a distance, 

 comparatively, the spark of the common electrical machine 

 This distance can pass through air. The answer to this is obvious: in- 



jnight be m- crease the number of the plates, and the striking distance 

 creased. . . 



will increase; for we see throughout, the intensity propor- 

 tioned to the number, and it probably may be carried to 

 such extent, as even to pass through a thicker plate of air, 

 Another proof than the common spark. The great similarity of the ap- 

 tity. " l Cn * P ea rance of the electric light of this battery in vacuo, and 

 that of the common machine, might also be urged as an ad- 

 ditional proof of the identity of their nature. 

 Numerous The effect of this large combination on imperfect con- 



■eombmation (] uc tors was, as may be supposed, very great; but of the 

 fused but little ' J . r £ • j? ' 



platiaa, same platina wire, of which the lour-teet plates fused 



eighteen inches, this battery melted but half an inch, though* 



had the effect been in the ratio of their surfaces, it should 



have fu;-ed nearly fourteen inches. 



Effect of the ^ ne absolute effect of a Voltaic apparatus, therefore, 



apparatus '» seems to be in the compound ratio of the number, and size 



mtk>of the" q ° of tnC !>»ates : the intensity of the electricity being as the 



»|pjbej&size. former, the quantity given out us the latter; consequently 



regard must be had, in its construction, to the purposes for 



which it is designed. For experiments on perfect conductors, 



very large plates are to be preferred, a small number of 



which will probably be sufficient; but where the resistance 



•I 



