198 /Miscellanies. 
3. New analysis of Brewsterite—Mr. Connell has repeated the 
analysis of this mineral, which Retzius, according to Berzelius, found 
to contain Silica, - » 57.285 
Alumina, - - 17.011 
Soda, 
Lime, _ E 1.14 
Water, - - - 17.872 
99.932 
Mr. Connell’s specimens were from Strontian, and gave 
Silica, - - 
Alumina, - - 17,492 
Strontia, - - 8.320.2:.c-21 
ta, - - 6.749 15.074 
ime, - - 1.346 
Oxide ofiron, - - -292 
ater, - - 12.584 
100.454 
Its formula may be expressed by oat S?+4AS83-+6Aq; or, if we 
suppose the proportion of the strontia and baryta to be 2 atoms of the 
former to 1 of the latter, the constitution will then be, 2 atoms bisili- 
cate of strontia +-1 atom bisilicate of baryta +12 atoms tersilicate of 
alumina +6 atoms of water.--(Idem. Jan. 1831, p. 35.) 
4. Polarizing Rocks.—The first observations concerning the mag- 
netic polarity of rocks were made by Baron Humboldt in 1796. He 
noticed it in a serpentine rock on the Haidberg, near Celle, in the coun 
try of Baireuth. It was afterwards observed in many other rocks, sucht 
as hornblende-slate, porphyry, trachyte, basalt, &c.** It is app’ 
g 
the property ; as indeed it shows itself with different purely magné 
iron stones in the greatest variety of degrees of strength, and there 
are some of these which show no magneto-polar action. Neither 
there any regularity in the position of the axes either in one and the 
same mass of rock in general, or a fixed correspondence, in the post 
tion of these axes, with the direction of the strata of the rocks. 
* For the discovery of Humboldt and those connected with it, see the saa” 
Blatt Algemeine Literaturzeitung, 1796 and 1797. Neues Bergmann’s Jour. i 
pp- 257 and 542. Gren’s Weues Jour. d. Chem. u. Phys. tv. V- Moll’s ee 
Berg.u. Huiten Kunde, 111, p. 301. V. Moll’s Neues Jahr. d. B. u- Hi, bee e ees 
Gilbert’s Annalen, neue Folge, x1v. Heft 1, p. 89. Goldfusz and Bischot sP As 
Statist. Beschreiburg d. Fichtelgeberges, 1, p. 139, and ibid. altere Reihe, xvitls 
297. 
