88 
Miscellany. 
acid of a specific gravity of 1.850. A precipitate of Prussian blue will 
be formed of good quality. 
Where an impure blue is wanted, an ounce and a half of a solution of 
sulphate of iron is to be mixed with a gallon of the lime water with 
which the gas has been purified. Fourteen ounces of sulphuric acid then 
to be added, a precipitate will form consisting of Prussian blue, com- 
bined with sulphate of lime. Repert. of Arts. 
Colouring principle of Cornelian. From the observations of Dufay, and 
the experiments of M. de Claubray, it appears that the colouring matter 
of the cornelian is not an oxide of iron, but of an organic nature. The 
latter chemist found that when powdered cornelians were mixed with 
black oxide of copper, in a porcelain retort, and heated to redness, car- 
bonic oxide and carbonic acid were disengaged, and hydro-acetic acid and 
a pyrogenous oil were formed. Jlnnal. de Chim. 
Crystallized Tin from Solution. Professor Mather states that having 
occasion to form a solution of muriate of tin, some muriatic acid was 
poured upon an excess of spongy grain tin. The solution was formed on 
the sand bath, and it was so concentrated as to be oily in its consistence. 
The solution being more concentrated than was desired, it was diluted 
and allowed to stand on the sand bath, exposed to the air. In a short 
time the undissolved tin was observed to be coated with crystals of me- 
tallic tin. Some of the crystals were small and granular, having many 
facets ; some were long acicular prisms, and others were in foliated plates 
and plumose, like the precipitated lead of the arbor saturni. One of the 
acicular crystals, of the diameter of a horsehair, was mounted on the re- 
flective goniometer. It had four brilliant planes, giving distinct reflected 
images, and each face inclined to the adjacent ones at angles of 90°. 
The experiment of crystallizing tin was repeated many times with the 
same result, using not only the spongy, but also the columnar grain tin. 
In the latter, the acid dissolved a crystalline structure, and probably it is 
owing to this crystalline structure that tin emits a peculiar crackling 
noise when bent. 
If the solution containing the crystals of tin be set aside in a cool place, 
for twenty-four hours, they redissolve. The concentrated solution, when 
set aside until cool, and then diluted with water, will also vegetate, but 
the crystals form more slowly than when the hot solution is diluted. The 
crystallization can be shown before a class in the lecture room, and it is 
more beautiful than that of the arbor Dianse. 
Arner. Journ. Sci. and Arts. 
