Mineralogy. lxxx¥ 
sioned the most laborious part of the investigations of mineralo- 
gists. .The known forms of calcareous spar exceed 600; and 
perhaps those of iron pyrites and of some other species, if they 
were fully examined, would not be found much fewer. Leblanc 
was ‘the first of the modern chemists that attempted to ac- 
count for this diversity; but the progress which he made was 
inconsiderable. The subject has been lately taken up by M. 
Beudant, who hes published a most interesting and elaborate 
paper on the subject. I regret that I am prevented, by want of 
room, from laying the substance of his researches before the 
reader. I can do no more than merely state the general results 
which he obtained. : ; : 
1. The state of the atmosphere, the greater or less rapidity 
of evaporation, the form of the vessel, its nature, the quantity 
of liquid, the state of its concentration, seem to have no effect 
whatever upon the crystalline forms which salts assume ; they 
merely influence their beauty and size. 
2. When the atmosphere is moist, the salts have a tendency 
to form crystalline vegetations on the edges of the vessel. 
3. Very dilute solutions, excluded from the air and prevented 
from evaporating, may yield crystals after a longer or shorter 
interval of time. But this is particularly the case with those 
salts which have but little solubility. 
4. The nature of the vessels, by exercising different attractions 
on the salts, occasions the crystals to deposit themselves more 
or less quickly, and to accumulate in different ways in different 
parts of the solution. If the vessels are covered with a coat 
of grease, the crystallization takes place only at the surface. 
5. The position in which the crystals are deposited in the 
midst of a liquid mass, has no other influence than that of pro- 
ducing more or less extension of the crystal in one direction, 
rather than another. The bounding faces are always of the 
usual number, and in the usual position. 
6. The temperature and electrical state seem to have no in- 
fluence on the forms of crystals ; excepting that at high tem- 
peratures crystallization is very irregular, and the saline masses 
produced are very fragile. 
7. Substances in suspension, almost permanent in a saline 
solution, have no effect in varying the crystalline form. These 
substances are often deposited in the crystal in concentric 
layers. 
8. The crystallization of a salt cannot take place in the midst 
of a deposit of foreign matters in very fine and incoherent par- - 
ticles, unless the deposit be covered to a certain height by 
the liquid. Crystals, formed in these circumstances, always 
contain a portion of the foreign matters which are found disse- 
minated more or less regularly in their mass, and never deposit- 
ed in concentric Jayers. When the solution is not much con- 
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