13S Analysis of the magnetical Pyrites. 



was added after the liquor had been boiled for a conbidcrs- 

 ble lime. The precipitate thus obtained was boiled wiili 

 lixivium of potash ; it was then edulcorated, dried, made 

 red-hot with wax in a covered porcelain crucible, was com- 

 pletely taken up by a magnet, and, being weighed, amounted 

 to 80 grains. 



C. The lixivium of potash was examined by muriate of 

 ammonia, but no alumina was obtained. 



D. To the filtrated liquor from which the iron had been 

 precipitated by anjmonia, muriate of barvtes was added 

 imtil it ceasea to produce any precipitate : this was then 

 digested with some very dilute muriatic acid ; was collected, 

 washed, and, after exposure to a low red heat for a few 

 minutes in a crucible of platina, weighed 153 grains. If, 

 therefore, the quantity of sulphur converted into sulphuric 

 3cid by the preceding operations, and precipitated by ba- 

 rytcs, be calculated according to the accurate experiments 

 of Mr. Chenevix, these 155 grains of sulphate of barytcs 

 will denote nearly 22*50 of sulphur ; so that, with the addi- 

 tion of the 14 grains previously obtained iu substance, the 

 total quantity will amount to 36'30. 



E. Moreover, from what has been stated it appears that 

 the iron which was obtained in the form of black oxide 

 weighed 80 grains ; and, by adding these SO grains to the 

 36-50 of sulphur, an increase of weight is found = 1(3*50. 

 This was evidently owing to the oxidlzement of the iron, 

 which, in the magnetical pyrites, exists quite, or very nearly, 

 in the metallic state, hut, by the operations of the analysis, 

 had received this addition. The real quantity of iron niu?t, 

 on this account, be estimated at 63"50. 



IQ.0 grains, therefore, of the magnetical pyrites yielded 



Sulphur I j^^ 22-50} ^^'^^ S™"^' 

 Iron - E. = • C3-50 



100' 



This analysis was repeated in a similar manner, excepting 

 that the whole was digested in nitric acid imtil the sul- 

 phur was entirely converted into sulphuric acid. To the 

 li({uor which remained after the separation of the iron by 

 ammonia, muriate of baryles was added, as before, and 

 formed a precipitate which weiohed 245 grains. Now, as 

 the sulphuric acid in sulphate of barytcs is esVimau'd by 

 'Mr. Chcuevix at 23*5 per cent., and the sulphur which is 

 I required 



