Inielligence and Miscellaneous Articles. 479 



Sulphur 19-24 



Antimony 29'77 



Silver 24'77 



Lead 24-91 



Copper 00-62 



Iron 00-26 



Zinc 00-36 



99-93 

 The above results indicate the constitution of the mineral to be 

 5 equivs. sulphur, 2 equivs. antimony, 1 equiv. silver, 1 equiv. lead. 

 In composition it approaches the schilfglaserz, described in Dufre- 

 noy's Mineralogy, containing, according to Wohler, — 



Sulphur 18-74 



Antimony 27-38 



Silver 22*93 



Lead 30 27 



99-32 

 Considerable difference in the composition of these two substances 

 is however observable ; the crystallographical characters of the 

 schilfglaserz serve to distinguish one from the other ; in fact, the 

 latter mineral crystallizes in the system of the right rhombic prism, 

 and gives well-marked cleavages ; whilst the new mineral has a 

 shining uneven fracture, without any indication of cleavage. It is 

 to be expected, however, that it will at some time be found in regular 

 crystals. 



The specimen brought by M. Castelnau comes from the Mexican 

 mines, and weighs about 14 lbs. One of its surfaces is sprinkled 

 with iron pyrites. From its size and appearance it may be pre- 

 sumed to form a workable seam. 



M. Damour proposes for this substance the name of brongniardite, 

 as a tribute of respect to the memory of the late M. Brongniart. — 

 Annates des Mines, vol. xvi. p. 227. 



ACTION OF SULPHATE OF MAGNESIA AND SULPHATE OF ZINC. 



M. SchaeufFele states, that when a saturated solution of sulphate 

 of magnesia is put in contact with pulverized sulphate of zinc, the 

 salt obtained differs from that procured by the inverse operation. In 

 the first case the crystals contain 12-59 per cent, of magnesia and 

 11*60 of oxide of zinc, whilst in the second case the quantities are 

 27-84 of oxide of zinc and only 0*27 of magnesia. 



The same fact is observed with regard to sulphate of iron in com- 

 bining with sulphate of zinc. If the first of these salts be taken in 

 powder, and the second in saturated solution, the crystals of the 

 double salt obtained contain 13-80 per cent, of oxide of zinc and 

 12*10 of oxide of iron ; whilst, on the contrary, if a saturated solu- 

 tion of sulphate of iron be taken, and the sulphate of zinc in powder, 

 the double salt formed contains 14*63 of oxide of iron and 12*05 

 only of oxide of zinc. 



