328 Progress of Foreign Science. 



our Journal, p. 169, we have described M. Berthier's mode of 

 analyzing minerals which contain alcaline matter. The follow- 

 ing Table of results seems important: 



The domites from Puy de Dome, and the vitreous lava, have 

 been called feld-spar lavas. 



1. Analysis of the CTT/stallized Calamine of Limbourgh (Elec- 

 tric oxide of Zinc, Haiiy,) by Professor Berzelius. (From 

 Schweigger's Journal for last December.) 



Mr. Smithson first distinguished several varieties of cala- 

 mine which have since formed a single species. That now.under 

 consideration was by him found to consist of, silica, 25 ; oxide 

 of zinc, 68.3; and water, 4.2=97.5. 



The silica and oxide are in the equivalent proportions, but 

 the water is in this respect anomalous. With a view of settling 

 this point, M. Berzelius undertook a careful analysis of the 

 minerals. On redissolving in ammonia, the precipitate by 

 subcarbonate of soda, from the sulphuric acid solution, he se- 

 parated completely the oxide of zinc from the lead, and found 

 of the latter 0.003 parts. The following is his result : 



Silica . . 

 Oxide of zmc 

 Water . . 

 Carbonic acid 

 Oxide of lead 



. 24.9 

 . 66.84 

 . 7.46 

 0.45 

 0.28 

 99.93 



f 26. 

 \ 66. 

 I 7. 



26.23 

 37 

 40 



100.00 



Representing this compound by the formula 2 zn.S-f-aq., and 

 subtracting the carbonate of zinc. 



2. Analysis of an arsenical pyrites, from Zinnwald, by Dr. du 

 Menil ; specific gravity, 6.064 ; constituents, iron 42.44, arse- 

 nic 52.12, sulphur 2.4. 



