556 



ANALYSIS OF PYRTTES. 



V. 



Ariatifsis of three Species of Fyrites^ hy Mr, Bucholz *. 



Analysis of 

 pyri(es. 



iVJlESSRS. Gehlen and Bucholz having particular reasons 

 for wishing to examine the observations of Proust on the 

 two compounds of iron and sulphur, they made their ex- 

 periments on an artificial sulphuret with a maximum of 

 sulphur, because they had not any native. Having after- 

 ward procured three difl'crent specimens of native pyrites; 

 Mr. B. determined to analyse them carefully, in consequence 

 the difference between the results of some eminent chemists. 

 The following are the component parts of pyrites: 



Component 

 parts according 

 to different 

 <Luthors. 



Sulphur. 



Iron. 



according to 

 Proust 

 Hatchet - 



Guenivcau f - 



Bucholz and Gehlen 



{i 



52-64 

 46-7(J 

 47-24 

 46-60 

 46-31 

 52-07 

 52-64 



Usual process 

 consumes much 

 time and acid. 



Procesf?adopt- 

 p«t to sare buth. 



47-36 

 53-24 

 52-76 

 53-40 

 53-69 

 47-93 

 47-36 



As the process generally adopted, which consists in 

 treating pyrites with weak nitric acid, requires a great deal 

 of acid and of time, Mr. Bucholz first endeavoured to find 

 a process, that should convert the pyrites into oxide of 

 iron and sulphuric acid with the least possible expenditure of 

 both, without occasioning any loss, and without giving in- 

 accurate results. 



. After various trials, the following method appeared to 

 him most speedy and certain. 100 grs. of pyrites, reduced 

 to very fine powder, were diffused in half an ounce of water 

 in a twelve ounce phial ; and concentrated nitric acid was 

 added, drop by drop, as long as a brisk effervescence took 

 place, with the evolution of red fumes. The mixture 



* Abnui^sd from the Annales de Chim. vol. Ixviii., p. 134. 

 translated from the Genuan by Bcrard. 



■\ For a careful analysis by Guenivcau, where the proportions 

 aie 45 iron, bb sulphur, see Journal, vol. xxi, p. 142. C. 



being 



