116 Scientific Intelligence. 
MgSi+6H i in accordance with this principle, are isomorphous. ‘Thus 
chrysolite and serpentine may be isomorphous. ‘The composition of 
the first, Mg3Si, is anhydrous and constant. Serpentine is hydrated 
and has a varying composition, wherever found, not affording a chem- 
ical formula. But examined with reference to M. Scheerer’s views, 
we observe that in all the best analyses of serpentine, the oxygen 
of the magnesia and of the protoxide of iron, added to one third 
the oxygen of the water, is equal to that of the silica; and ‘conse- 
quently serpentine is a variable mixture of two isomorphous silicates, 
Me3Si, and Mg2Si--3#. M. Scheerer has brought forward numerous 
other examples from among silicates, sulphates, &c. 
M. Scheerer has also discovered that oxide of copper may be re- 
~ placed in an isomorphous manner by two atoms of water. 
‘We inay now see clearly why so many hydrated minerals have never 
given uniform results, even with the most careful analyses. 
The memoir of Scheerer will appear in two or three er in Pog- 
gendorff’s Annalen at Berlin. ‘The facts here briefly stated were com- 
municated by him to the Academy of Sciences at Stockholm, at its 
last session. 
16. Influence of Magnetism on Crystallization ; by R. Hunt, (Phil. 
Mag., Jan. 1846, p. 1.)—It has been supposed by many writers that 
electric or magneti¢ currents must have an influence on the position 
and character of forming crystals. The experiments of Mr. Hunt 
illustrate and — ere point in an interesting and satisfactory 
manner. ~ 
A tube containing a concentrated solution of nitrate of silver, was 
placed against -the poles of a permanent horse-shoe magnet, and an- 
other tube was set away by itself. Crystallization commenced first 
in the former, and the crystals started at different angles from the glass 
where it was in contact with the magnet; none forming above the 
magnet. In the other tube the crystals had no regular arrangement. 
Ina second and third experiment, by using for comparison another 
metal, he shows that the cooling influence of the metal was not the 
cause of this arrangement of the crystals, The crystals, when both 
poles of the magnet were placed against a capsule containing the same 
salt in solution, and a piece of metal not magnetic on the opposite side, 
formed in the fluid almost wholly adjoining the north pole ; only three 
long crystals appeared opposite the south pole, and these were directed 
towards those springing from the north pole. The same result was 
obtained i in four ee of the experiment. 
“~ steel needle ign dh rac aicaena one, to each pole of a ‘ie gda mag: 
. © were made to dip into a solution of nitrate of silver in 
