MR. HA.TCHETT ON MAGNETICAL PYRITES. 



15 



obferved confpicuoufly powerfal in one fpecie!: of iron ore, this 

 has been always emphatically called the Magnet, * and is faid 

 to conlift of metallic iron combined with from 10 to 20 per 

 cent, oi oxygen. 



From the Tadis, however, which have been recently dated. The fulphuret 



I /• 1 n 4i '^ ^ different 



we now hnd that there is another natural lubJtance, apparently ^^^ ^^ xfngaeu 



very different from the magnet in chemical compofition, but 

 nev^rtiielefs approaching very nearly to it in power, which is 

 found in feveral parts of our globe, and particularly in a pro- 

 vince of this kingdom, where it conftitutes a vein, running 

 north and foutb, of a coniiderable extent, and feveral yards in 

 width and thicknefs. 



From the experiments alfo, which have been made on the The pliofphuret 

 arliBcial preparation of this fubftance, we find, that it is capable " 

 o{' receiving the magnetic properties when the proportion of 

 fulpluir amounts to 37 per cent, and is ftill powerfully attraded 

 when a much larger quantity of fulphur is prefent. There 

 is, however, fome point at which all thefe effeds ceafe, and 

 this point appears to be, when the fulphur is in fome proportion 

 between 45 or 46 and 52 per cent. The preceding experiments 

 have aifo proved, that iron when combined with phofphorus, 

 likewife polfeffes the power of becoming a magnet to a very 

 remarkable degree ; and, by the fimilarity, in this refpecl, of the 

 carburet of iron called fteel, to the above fulphuret and phof- 

 phuret, a very remarkable analogy is efiabliflied between the 

 efFcds produced on iron, by carbon, fulphur, and phofpho- 

 rus. 



Carbon, when combined in a very large proportion with iron, of arhwets, 

 forms the carburet of that metal called plumbago; a brittle P'"""''3go '* n*^ 

 fubftance, infoluble in muriatic acid, and def^itute of rriagne- other fteel cotn- 

 tical properties. But, fmaller proportions of carbon, with the pounds form po^- 

 fame metal, conflitute the various carburets included between S - ^ 



black call iron and foft caft fteel;t bodies which are more or 



Mi 



* In a future Paper, It is my intention to give an account of 

 fome comparative analyfes of the varieties of this fubftance. 



f " When the carbon exceeds, the compound is carburet of iron 

 ** or plumbago: when the iron exceeds, the compound is fteel, or 

 ** caft iron, in various ftates, according to the proportion. AU 

 ** thefe compounds may be confidered as fubcarburets of iron.*'— 

 ThoiTiibn's Syftem of Chemiftry^ Vol. I. p. Idj. 



Mr. 



