1820.] ^- Stromeyer on Polyhalite. 439 



Therefore 100 parts of polyhalite consist of 



Anhydrous sulphate of hme. ..,.••• 44-5026 

 Anhydrous sulphate of magnesia. . . 19-50by 



Sulphate of potash n qa'^o 



Red oxide of iron ^-'^^•^■j 



91-9144 



It now remained for me to determine the quantity of muriate 

 of soda met with in polyhalite, having ascertamed ^ro^^he pie- 

 cedhig experiments that this salt is always f«^'^d mixed with he 

 mhreial, although only accidentally, and in such a small portion 

 as frequently to be disregarded. . , 



For this purpose, since the eye, however assisted, is not able 

 to detect aLr^ticle of salt in the fossil, I dissolved m nitric acid 

 7°088 -rms of finely powdered polyhalite, and having poured a 

 conskieS)i; quantity of water on the solution, kept dropping lu 

 some nitrate of silver until the precipitation of the muriate of 



"'fthen sTthe' deturbated liquor by for some days in a dark 

 Dlace in order that the precipitate might subside and atter- 

 Cds carefully collected the muriate of silver, which, bemg weU 

 rlripd weio'hed 0'033 grm. , ■ -^ i. j u,. 



But now° 100 parts Sf muriate of soda, ^^^en precipitated bj 



nitrate of silver, according to the e^P^""^^^^*?^^^ ^°^^V f uriat 

 143-5 parts of muriate of silver; whence 0-033 grm. of inunate 

 of sUver are equal to 0-01355 grm. of muriate of soda ; so that 

 100 parts of polyhalite contain of muriate of soda or rock salt, 



O-l^l^- (G.) 



But if we take the average of what we collect respecting the 

 p^ortLTonhe various -nstituent parts of Uns mm^^^^^^^^^^ 

 each of these experiments and analyses, it follows that in lut. 

 parts of polyhalite there are 



,jr . 5-9335 



Water • •. AA.iAOOi 



Anhydrous sulphate of lime. .•.•••• ^4 /^^^ 

 Anhydrous sulphate of magnesia .. ^^'^J^!' 



Sulphate of potash ''o-1910 



Muriate of soda ^ ^ 



Red oxide of iron ^-66(0 



98-9434 



On reckoning the portion of sulphate <>f l^"^^, ^^ JE^f^he 

 combined with water, and judging its quantity ^om tha^ot the 

 water found in the fo3sil, there are in 100 parts of polyhalite 



