DOVE ON THE ELECTRICITY OF INDUCTION. 181 



then an imperceptible portion only passes through it ; for if u 

 is in constant metallic connexion, and I and II are connected 

 by the voltameter, no decomposition ensues. Similar relations 

 are observed with I and III when connexion is broken at u in 

 azimuth 90°, or 90° and 270°, i. e. when the voltameter, after 

 having formed for some time a secondary connexion, now be- 

 comes the chief connexion. Gas is then produced in the volta- 

 meter between I and II, with one break only in azimuth 90°, 

 therefore with a current in a like direction, and moreover much 

 more gas with empty spirals than when iron is contained in 

 them. 



The chemical effects therefore correspond with the phaeuo- 

 mena observed with the sparks. Here also the phaenomena de- 

 pendent upon the extra current are more distinct, when the hand 

 of the pachytrope is arranged for physical than when it is ar- 

 ranged for physiological effects. 



86. Lastly, it may be asked, what phaenomena will occur when 

 the current flowing at the commencement in a metallic circuit 

 without any secondary connexion is on the breaking of this cir- 

 cuit closed by the voltameter .-' In the drawing, the moment con- 

 nexion is broken at m, I and III or II and III must first be con- 

 nected by the voltameter. This is effected in the following man- 

 ! ner: — Suppose the primary current to be only once inteiTupted 

 i| in azimuth 90°, and that the voltameter is inserted between 8) 

 I and 15). The springs 13) and 14) are inclined so much to- 

 I wards the left upon the cylinder W4*, that when the spring 3) 

 I comes in contact with wood, the spring 14) on W4 touches metal, 

 ,1 and vice versa, whilst 13) is constantly in connexion with metal. 

 l| Besides this, 7) is connected with 12) by a cross wire. As long 

 I as 3) is in contact with metal on w^, the connexion is made from 

 I «>3, through 5), 6), the spiral, and 1), 3) to w^, whilst the vol- 

 I tameter, in consequence of the interruption on w^, forms no se- 

 I condary connexion. When however 3) reaches the inserted 

 I wood, the connexion from w, to w^ is then effected through 5), 

 I 7)j 12), 13), W4, 15), the voltameter, and 8), 9); the spiral 

 I is therefore excluded. It is obvious however that the true ac- 



• The inserted plate of wood on u\, wliich is next to the cylinder u-^, is in- 

 tended for alternatinn; currents, and covers therefore only one-sixth of tlie cir- 

 cumference, as it again occurs in a diametrically opposite position. The inserted 

 Siece of wood nearest to the end of the axis B occupies on the contrary one- 

 alf of the circumference of the cylinder. 



