ON THE PHENOMENA OF CRYSTALLIZATION. 
285 
mass were similarly fitted up ; these, however, 
like the princij)al one, proving: almost value- 
ie'S. the Professor declined making further 
trials, and finally laid aside all thouglits of the 
matter. 
Some years afterwards, I think in 1781, my 
father, casually rummaging a Uimher-hox 
which stood under his woih-bench, perceived 
some small fragments of ihe almost foigotten 
loadstone surrounded by iion filings and other 
ferruginous dust, and remarking that one of 
tliese fragments carried a huger heard of filings 
than the others, he was thereby induced, at 
his fir.'t leisure, to bestow, what he then 
thought, a little hopeless labour in grinding 
it to a proper shape with due regaid to its 
poles. J he diminutive iron arms were attach- 
ed in a temporary manner hy means of a 
thiead, wlien, to his great surprise, its first 
load, though liasiily applied and supposed to 
be in excess, required sensible force for its 
reiiioval. 
It now seemed woithy of some additional 
labour; the form in legard to polarity was 
re-ex unineil, and when finished in this res- 
pect, the stone, af'er being weighed, was with 
its arming enclosed in a thin case of goid, 
having a ring at top for suspending it. Its 
load, a pyramidal sliaped friece of soft iron, 
was now made of what was judged a weiedit 
rather undei' its maximum power, that is, 783 
grains; the stone itself weighs precisely tw o 
and a half grains; it cariies, therefore, 313 
times its own weight. 
It is now aliout 55 years since this little 
spark of the mine was fi:st enclosed ; upwards 
of 30 years ago the case was Opened, in oi der 
to apply arms of perhaps a better shape ; the 
old ones, however, appealing'' in all respect.s 
fau’tless, the whole was immediately put 
togeiher in its original slate. 
Scient'fic indviduals have frequently sug- 
gested the pi'opiiety of keeping it with the 
load constantly attached, as a mean, they al- 
lege, of increasing its strength. This, I ap- 
prehend, is lathet a gialuit'ons assumption; 
besides, constant adhei-ion could n t be main- 
tained owing tu the liemors incessantly taking 
[lace in eveiy dwelling house. '1 hong hit is 
not doubted, that, by careful application, the 
load could he increased to considerahly more 
than 800 grains ; still, as there is re'ason for 
thinking that violent separation of the load, 
under such circumstances, might prove 
irijnrions, the trial has never been matle. 
'J'he same mass of iron has been used as its 
load from the leginnitig, and is placed merely 
in contact with tiie arms. The power of 
adhesion seems to be the same as it has ever 
been. 
James Crichton. 
Glasgow, ls< March, 1836. 
PHENOMENA OF CRYSTALLIZA- 
TION. 
When the formation of crystals are ob- 
served under the microscope according to 
Ehrenberg, the first thing which attracts at- 
tention is a rapid action going on about the 
crystal ; suddenly a solid point forms in the 
transparent liquid, appreciable by its opales- 
cence, and increases with astonisliing ra- 
pidity, shewing that this point concentrates 
and condenses the saline particles previously 
dispersed and suspended in the water. This 
concentration supposes a motion towards the 
centre, and one is apt to think that the 
aggregation of the atoms is of such a nature 
that the density will increase towards the 
edge. In this view it is rather surprising 
that there should be no motion nor agita- 
tion in the neighbourhood of the crystal. In 
order to investigate the subject more ac- 
curately, Ehrenberg examined strongly 
coloured crystals. He dissolved bichro- 
mate of potash and sulphate of copper 
in water : he could not discover in either 
case any visible current resulting from the 
concentration of the coloured particles, nor 
an aggregation around the crystal, while it 
increased with great rapidity ; yet even by 
sprinkling a fine powder over the liquid 
which crystallized, uo currents could be 
detected. Hence, crystallization is analo- 
gous to the phenomena which, it is generally 
supposed, take place when masses aggregate 
in space. A nebulous appearance first 
occurs, the matter of wliich gradually 
condenses in the centre, then a kernel is 
formed with an areola, and lastly a properly 
formed world is completed. 
Ehrenberg has carefully studied some 
drops of a solution of common salt, and has 
observed that hexagonal tables are formed 
at the limit of evaporation often very regular 
but frequently deposited one upon the other. 
In the middle of these very delicate hexago- 
nal tables a point was suddenly formed 
which attracted to it the mass of tables. 
Immediately the observer noticed there a 
small tube increasing with immense rapidity 
and enlarging as the tables diminished. 
The waters of the Baltic and N. Sea are par- 
ticularly fitted for these observations. Con- 
ceiving that the phenomena might be owing 
to the presence of two different salts, he 
made an experiment upon common salt, 
chemically pure and dissolved in distilled 
water. In this case he observed the same, 
only not so frequently ; the cubes being 
generally formed immediately. Mitscher- 
lich has shown that common salt forms 
hexagonal plates at very low temperatures. 
But in the present case the temperature 
was that of the atmosphere. Did the cold 
produced by the evaporation influence it ? — ■ 
Poggendorff^s Ann. No. x., 1835. 
PRESERVATION OF ANIMAL SUB- 
STANCES BY CARBONIZATION. 
[A short notice of this new discovery ap- 
peared in our 667th Number. The following 
