738 



PLLTCKER OX THE DETERMINATION OF THE 



37- The following table, which indicates the magnetism of the 

 atoms of some chemical compounds of iron, nickel and man- 

 ganese, has been calculated in accordance with the preceding 

 paragraph. 



1. Irou 



2. Magnetic iron ore 



3. Peroxide of iron I 



4. Peroxide of iron II 



5. Red haematite 



6. Micaceous iron ore 



7. H ydrated oxide of iron 



8. Blood-stone 



9. Pyrites 



10. Persulphate of iron 



1 1 . Green vitriol 



12. Protoxide of nickel 



13. Hydrated protoxide of nickel 



14. Hydrated oxide of manganese , 



15. Protoperoxide of manganese... 



In solution. 



1. Protosulphate of iron . 



2. Persulphate of iron .... 



3. Pernitrate of iron 



4. Protonitrate of nickel . 



5. Protochloride of irou 



6. Perchloride of iron . . . . 



7. Protochloride of nickel . 



Composition. 



Fe 

 FeO + Fe^Qs 



Fe' 03 



Fe2 03 + 2HO 

 Fe2 03-|- HO 



FeS- 



Fe2 03 3S03 



Fe0S03 + 7H0 



NiO 



NiO + HO 



Mn2 03 + HO 



MnO + 2Mn03 



FeOSO' 



Fe2 03 3SO' 



Fe2 0='3NOs 



NiONOS 



FeCl* 



Fe2C13 



NiCl 



Magnetism 

 of the atom. 



100,000 



166,656 



1,428 



818 



392 



1,522 



592 



480 



321 



698 



385 



47 



190 



224 



696 



594 

 938 

 820 

 219 

 490 

 1,474 

 229 



I need hardly point out expressly, that I cannot regard the 

 numbers in the preceding, as also those in the former table, as 

 by any means definitely fixed. They will certainly undergo cor- 



gramme of the two substances, or what is the same, multiply them by their 

 respective atomic weights. In this manner we get in the above example — 



350 . 100,000 : 1000 . 500 = 100,000 : ^^ . 500. 



3a0 



Hence, if we again place the atomic magnetism of iron at 100,000, that of the 



peroxide is 500, multiplied by its atomic weight and divided by the atomic 



weight of the iron. 



On the other hand, if we take a given quantity of iron, at one time in its 

 pure state, at another in combination with oxygen, in the form of peroxide, 

 the magnetic attraction is different in both cases. To find the magnetism of 

 the gramme of iron in the peroxide, we must evidently multiply the magnetism 

 of this oxide,, for which the table in the 23rd paragraph gives 500, by 



1000 

 n . ooO' 

 in which n denotes the number of the atoms of iron contained in an atom of 

 the compound. 



From this example we see that the magnetism of iron, in any of its chemical 

 compounds, is equal to the magnetism of the atoms of this iron compound, 

 divided by the number of atoms of iron which an atom of this compound con- 

 tains, provided that in each case we take pure uncombined iron as the point of 

 comparison. 



