S06 
Scimtijic Intelligence. 
have found pyro-electricity in either of these minerals, but only 
in the mesotype pyramidale. The mesotype epointee or apo- 
phyllite indeed, exhibits no electricity whatever by heat,-^ as we 
have ascertained^ with very large crystals, the largest we believe 
that have yet been obtained with perfect summits ; but we have 
found that there is pyro-electricity in the, nadelsteln or meso- 
type aciculaire^ the pyramidal summit having vitreous, and the 
root of the crystal resinous electricity Br Brewster has as- 
certained that Nadelsteln is quite a different substance from 
Mesotype. 
19 . Electrical Fish.-^A fish resembling the Silu7'us electricus 
was brought on board the Congo from Embomma, upon the river 
Zaire. According to the accounts of the natives, it communi- 
cated a severe shock to the hand and arm, if any person touched 
it when alive, or, as they described the effect, ‘‘it shot through 
all the arm.*” Mr McKerrow describes it as three feet six. 
inches long ; head large, broad and compressed ; mouth fur- 
nished with six long cirrhi, four on the under, and tvo on the 
upper-jaw ; mandibles dentated ; tongue short and eyes small ; 
body without scales ; pectoral fins near the branchial openings^ 
the ventral fins near the anus ; dorsal fins soft, and placed near 
the tail ; upper parts of the body thickly spotted blacky and the 
under of a yellowish white; skin exceedingly thick. NarrOr- 
five of an Expedition^ under Captain Tuckey, p. 859. 
I 
MAGNETISM. 
20. Magnetic qualities of Mica. — M. Biot of the Academy of 
Sciences, has lately made some very interesting experiments on 
the magnetic qualities of two kinds of mica, one of which came 
from Siberia, and the other from Zinwald in Bohemia, mixed 
with crystals of tin. Although these two micas are very trans- 
parent, yet M. Vauqtielin found, that the Bohemian mica con- 
tained about 20 per cent, of the oxide of iron. Before he analy- 
sed the Siberian mica, M. Biot examined their magnetic pro- 
perties by the ingenious method of Coulomb, of making a rec- 
tangular plate of each oscillate between the opposite poles 
of two strong magnets. These plates tv ere suspended by a deli- 
* In the Memoirs of the Institute, tom. i. p. 55., HaUy assures us that the- 
pyramidal summit of mesotype possesses resinous electricity ; and in his Traite de 
Mineralogies yol. ili. p. 160,, he says that it possesses vi(reovs electricity.' 
