M. E. Stohrer on an Improved Induction Apparatus. 55 



the mesolin of Berzelius, but that is Levyne). I would propose 

 that the unmeaning mesotype be exchanged for the expressive 

 natrolite ; that mesolite, as being in reality the intermediate 

 mineral, be retained ; and that mesole give place to Faroelite, 

 after the locality whence we obtain the choicest specimens of the 

 mineral. 



From their composition they will rank as follows : — 



Natrolite . NaO, SiO^ + APO^, SiO^ +2H0. 



Fargite ? . (2NaO, CaO) 2810^ + 3(AF 0^ SiO^) + 7H0. 



Faroelite . (NaO,2CaO) 3Si03 + 3(A12 0^, SiO^) + 8H0. 



Mesolite . (NaO,2CaO) SSiQa + 3(A12 0^, SiO^) + 8H0. 



Scolezite . . CaO, SiO^, + APO^ SiO^ +3H0. 



VII. On an Improved Induction Apparatus. 

 By Emil Stohrer*. 



SINCE attempts have been made to construct induction 

 apparatus of larger dimensions in order to obtain elec- 

 tric cun-ents which should, as it were, stand midway between 

 those obtained from the electric machine and those obtained 

 from the voltaic battery, several physicists and artists have 

 been occupied with the study of the phsenomena connected with 

 the subject. Probably what has already been accomplished is 

 far from the perfection which it is possible to confer upon 

 these instruments; and there is no strong reason against the 

 supposition, that, with comparatively small means, sparks several 

 inches in length may be obtained at the extremities of the wire 

 of the induction coil, if the necessary insulation can be effected 

 without removing the wire too far from the central core. The 

 surrounding layer must be completely impenetrable to sparks 

 which might spring from one series of coils to another. 



In the year 1854 I constructed an induction apparatus in 

 which I endeavoured, as M. Sinsteden has done, to turn to ac- 

 count the advantage possessed by magnets of the horseshoe form 

 over bar magnets. The result was not that which I hoped for ; 

 for after the removal of the iron crossjiiece which united both 

 limbs of the magnet, each bar singly showed a strong induction 

 current. It may be that the magnetic inertia of the massive 

 piece of iron is the cause of this, although subsequent experi- 

 ments on the advantages of bundles of iron wire over the 

 massive iron core showed that too much weight must not be 

 attached to the action of the iron by its temj)orary magnetism. 

 The same was observed by I'rof. Poggendorff. According to him, 



* From Poggeudoift's Annakn, May lS5fi. 



