2G0 



THE GEOLOGIST. 



form large stalactites in caverns near a mine of copper-pyrites ; its 

 colour is that of sulphate of copper, in the parts freshly broken (but 

 with a green ochraceous tint on the exterior), whilst its crystalline 

 form is that of sulphate of iron. On analysis, it turns out to be sul- 

 phate of protoxide of iron, in which part of the oxide of iron is replaced 

 by a corresponding quantity of oxide of copper. The figures obtained 

 in M. Pisani's analysis are as follows : — 



Oxygen. Proportion. 

 Oxide of copper . . . 15.56 . . 3.14) , 

 Protoxide of iron . . 10.98 . . 2.44 j * * 

 Sulphuric acid . . . 29.90 . . 17.94 . . 3 

 Water 43.56 . . 38.72 . . 7 



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This composition leads to the formula : — | 0, SO^ + 7 HO. 



We have also analysed this new mineral, and our figures coincide very 

 closely with those above.* The formula arrived at is that of common 

 green vitriol in which a certain quantity of iron is replaced by cop- 

 per, the crystalline form having remained intact. It is probable that 

 the natural production in question has been formed in the waters that 

 filter through the beds of copper-pyrites, and that it could be formed 

 artificially in the laboratory. 



Tungsten is a metal which has been hitherto little studied in a 

 practical point of view. It appears destined, however, to operate a 

 complete revolution in the manufacture of steel. It has been lately 

 affirmed that an alloy formed of 80 per cent, of steel and 20 per cent, 

 of tungsten, possesses a degree of hardness that has never yet been 

 obtained in the manufacture of steel. This alloy works upon the 

 latter, and can even cut it. Experiments have been made with this 

 new composition at Vienna, Dresden, and at Neustadt-Ebertswalde, 

 and considerable quantities of the alloy are being manufactured, it is 

 said, in that part of the world. Many old tin-mines have been bought 

 up with a view of extracting tungsten-ore, and considerable sums 

 have been given for mines that had ceased to be worked long ago. 



* Another sample of the same substance analysed by ourselves gave the follow- 

 ing result : — 



Oxygen. Proportion. 



Oxide of copper . . .15.86. . . 3.17) , 



Protoxide of iron . . .11.00. . . 2.44 j " * * 



Sulphuric acid .... 28.08 . . . 16.85 ... 3 



Water 45.06 . . . 40.05 ... 7 



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Formula :-~(Fe"Cu) S + 7 ll. 

 In the result given in the text there is evidently a slight excess of acid in pro- 

 portion to the quantity of oxide found. We have proposed for this mineral the 

 name of Vitriolitc.—T. L. P. 



