330 OXIDATIONS 0* IRON, 



vSnpposed has been differently explained, according to the manner I* 



causes or this. w hich metallic calces were considered. Previous to *he 

 Loss ofphlogis- pneumatic theory, the magnetism was ascribed to the pre- 

 sence of phlogiston. After the labours of Lavoisier had 

 #xigenaii©n. shewn, that the formation of metallic calces was owing to 

 the combination of oxigen with the metal, chemists naturally 

 inferred, that the oxigen destroyed the magnetism : and as 

 on the other hand facts seemed to prove, that magnetism 

 was annihilated in oxides highly loaded with oxigen, it was 

 established as a principle, that oxides of iron at a maximum^ 

 Or red oxides, were not magnetic. 

 Tfiis incomis- This principle, which does not agree with the fact I 

 f act5 have just related, embarrassed several philosophers in ex- 



Oxide at a plaining certain phenomena. The celebrated Baron von 

 magnetic. Humboldt,, who discovered magnetic polarity in a serpen- 



tine, could not account for this property in a mineral, 

 which appeared on analysis to contain only superoxigenated 

 This denied bv oxide. On this occasion Guyton observed, that the term 

 uy on, of superoxigenated, employed by the Baron, was inaccu- 



rate, for these two properties of being magnetic and super- 

 oxigenated were incompatible ', and that the magnetism of 

 the Saxon serpentine, and of othe« minerals which do not 

 afford green oxide by analysis, should lead us to suppose 

 Hauy's mode cf intermediate oxidations of iron. Mr. Hatty, the learned 

 the°re"tyration natlira -l philosopher, to whom magnetism is indebted for 

 of magnetism very perspicuous elucidations, has likewise suffered himself 

 ^o an o. e by ^ ^ j C( j awa y jjy ^he c h cm ists ; and, endeavouring to ac- 

 count for the magnetism, which some red oxides of iron ac- 

 quire when strongly heated, says, that u this is owing to 

 *' the heat reducing some particles of the oxide, at the same 

 * c time that it assists the magnetic action of the globe, &c.'* 

 At first I subscribed to such respectable authorities, be- 

 cause, as Bacon observes, onortet cdiscentem credere ; and 

 because, in the commencement of these researches, I tried 

 several red oxides, obtained from different solutions of iron, 

 •as well as several aperitive saffrons of steel, which did not 

 Magnetic qxI- give me the least sign of magnetism. But as I afterward 

 Acs with much p £r ceived ? that oxides greatly loaded with oxigen, or such 

 as contained '50 or -56, retained their magnetism, whilst 



others 



