INTENSITY OF MAGNETIC AND DIAMAGNETIC FORCES. 7^7 



36. The relative magnetism of the atoms of those substances 

 which have been examined may be readily deduced from the 

 tabular sketch given in paragraph 23 ; for when we have deter- 

 mined the relative magnetism of the iron in the various chemical 

 compounds, for the same weight, this is also the relative mag- 

 netism of the atoms of these substances, provided they contain a 

 single atom of iron only. When the compound atoms of the sub- 

 stances contain 2 or 3 atoms of iron, we must multiply the num- 

 bers given in the table by 2 or 3, to find the magnetism of these 

 atoms. Thus, for instance, if the magnetism of the atom of iron 

 be placed at 100,000, the magnetism of an atom of green vitriol 

 (FeOSO^ + 7H0) is equal to 385, whilst that of an atom of per- 

 sulphate of iron (Fe^O^SSO^) is = 2-349 = 698. 



The tabular sketch moreover gives about 45 as the number 

 representing the magnetism of the nickel in the protoxide of 

 nickel, and the number 180 as that of the hydrated protoxide of 

 nickel. The proportion of these numbers is also the proportion 

 of the magnetism of an atom of protoxide of nickel and that of 

 an atom of hydrated protoxide of nickel. However, to be enabled 

 to compare these numbers with those relating to iron and its 



compounds, we must multiply them by - , the quotient of 



the atomic weight of iron into that of nickel. 



For the same purpose we must first multiply the magnetisn^ 



of the manganese contained in the hydrated oxide (Mn^ O^ 



-1-HO), for which the table gives 116, by 2, on account of the 



double atom of manganese ; the magnetism of the protoperoxide 



(MnO + Mn^ O^), which was determined to be equal to 230, by 3, 



on account of the ternary atom of manganese, and then in both 



cases the quotient of the atomic weight of the iron into the 



X • . w r., 1- 344-684^ 



atomic weight of the manganese by *. 



* When at one time we speak of the magnetism which a giren quantity of 

 iron in different chemical compounds possesses, and at another of the mag- 

 netism of the atoms of these different compounds, we express ideas wiiich arise 

 from totally different views. It lias however already been stated that both 

 ideas stand in exact relation ; and this will be still more clearly seen from the 

 following remarks. 



If e.g. we take iron and the peroxide I., we have as the relation of the 

 magnetism of these substances, for the same weights, where about a gramme of 

 each is uniformly diffused within the watch-glass, by the table in paragraph 23, 



1 00,000 : .500. 

 To deduce the relation of the magnetism of the atoms from this, we must divide 

 the above numbers respectively by the number of atoms contained in each 



