B. G. Bredberg o7i the green Garnet of Sala. 423 



The difficulty with regard to fluoboric gas consists, probably, 

 in its affinity for sulphuric acid, which, as Dr. Davy has 

 shown, is so great as to raise the sulphuric acid with it in va- 

 pour. The experiments will however be continued on these 

 and other gases, in the hopes that some of them, at least, will 

 ultimately condense. 



LXXXVIII. Ati Examination of the green Gar?iet of Sala. 



By B. G. Bredberg.* 

 T^HE garnet of Sala, according to Haliy's crystallographical 

 -*■ nomenclature, is Grenat trapezoidal, since it is bounded 

 by 24 trapeziums, which are perceptibly striated parallel to 

 the greater diagonal. The crystals are of a brownish yellow, 

 sometimes of a yellowish green colour. Their surface has a 

 resinous lustre ; fracture uneven ; lustre of the fracture dull ; 

 m thin splinters transparent; sometimes the crystals are semi- 

 transparent throughout. They occur in a matrix of com- 

 mon limestone with crystals of calcareous spar, galena, and 

 blende. At present this gai'net is only met with in collections, 

 since it has not been found for a long time in the mine itself. 

 The specific gravity of a regular crystal was 3*746. Its re- 

 sult before the blowpipe is described in Berzelius's treatise on 

 the application of that instrument as translated (into German) by 

 H. Rose, p. 259.-t- The experiments with the blowpipe there 

 mentioned, were undertaken with that species of garnet which 

 is the subject of the analysis No. 2 ; that which was made use 

 of for analysis No. 1 gave, on trying it before the blowpipe, a 

 perfectly similar result. The analyses were made in the la- 

 boratory of Prof. Berzelius, where I had a favourable oppor- 

 tunity of acquiring the most preferable analytical method. 



For the analysis No. 1 regular crystals were employed of 

 a beautiful specimen, which, with sevei'al others, was found in 

 the old mine b}^ M. Pihl, captain of the mines, in the year 1 780. 



In No. 2, intended as a correcting analysis, crystals from 

 the collection ot Prof Berzelius were made use of. The 



* Orij^inally published in the Trans. Roy. Acad. Stockh., but above from 

 a translation in Schwcigger and Meinccke's Journal, N. R., band viii. p. 11. 



-f- In Mr. ChiUh-en's valuable translation of" this work into our own 

 languaj^e the results obtained by subjecting tliis mineral to the agency of" 

 the bl<)W[)i|)e are tims described, at p. 282. " Fuses (without lulditiou), with 

 strong intumescence, into a black brilliant jjlass. With horax fuses slowly 

 and difficultly into a glass coloured by iron. With salt of phonphorus de- 

 composes slowly, and leaves a silica skeleton. The tint from iron disap- 

 pears on cooling. With soda decomposes and intumesces, but afterwards 

 fuses into a black brilliant globule. On platiua foil exhibits traces of man- 

 ganese." — EuiT. 



specimen 



