INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 729 



fill ; it experienced an attraction of 2*94 grms. ; although, if the 

 protoxide were the only magnetic agent in the hydrate, this 

 attraction should have exceeded 6 grms., because the protoxide 

 was now comparatively nearer the magnet. 



However, the attraction of the freshly-prepared protoxide of 

 nickel exceeded the attraction of the original ; perhaps because 

 the expulsion of the water was still not complete. 



22. Lastly, a third series of experiments was made, the results 

 of which 1 shall collect in the following table, which corresponds 

 to the former one. The magnetism in this case also was excited 

 by six Grove's elements. 



1 part iron, 25 lard 



1 part magnetic iron ore, 25 lard 



Gray oxide of manganese before being"! 



heated to redness. Powdered. J 



Gray oxide of manganese after being 1 



heated to redness. Powdered. j 



Crystals of protosulphate of ii-on. Pow- \ 



dered. J 



Protonitrate of nickel. Solution 



Protochloride of nickel. Solution 



grms. 

 10-850 

 11000 



23-901 

 22-869 

 15-978 



1-377 

 1-671 



86- 135 

 8-470 



18-570 



6-300 



1-450 

 1-830 



D. 



grms. 



203-592 

 0354 



0-812 



0-394 



grms. 



505-300 



1-053 

 1-095 



The attraction of the empty watch-glass, the former with an- 

 other ground glass cover, simultaneously with this and the brass 

 ring, amounted to 



0-375 grm. ; 



and when filled with lard only, to 



0-240 grm. 

 From the attractions found by the direct weighings, the latter 

 number has been deducted in the case of the lard mixture in the 

 third column, and the former in the case of the powdered sub- 

 stances : in the solutions, making an approximate allowance 

 for the diamagnetism of the water, we deducted 

 0-275 grm. 

 The attraction given in the column D refers, in the case of the 

 (as finely as possible) powdered magnetic iron ore, to this inde- 

 pendently of the lard mixed with it. 



• The weights of the quantities of protoxide of nickel obtained from the two 

 solutions were respectively — 



1-751 grm. 

 2-123 grms. 



