MANUFACTURE OP PROTOCHLORIDE OP TIN. 
41 
triangles, and which upon closer examination under the 
microscope are formed exactly like those scalariform pyra- 
mids, composed of innumerable cubes, of chloride of potas- 
sium, chloride of sodium, &c.; the spicula above-mentioned 
are likewise scalariform pyramids, elongated in one direc- 
tion, and upon which numerous minute, very regularly 
formed cubes usually occur. When the separation takes 
place more slowly from less concentrated liquids, and espe- 
cially when large quantities are operated upon, very regu- 
lar four-sided columns are obtained. When, on the con- 
trary, a solution of tin is made to support a stratum of 
dilute muriatic acid, or a mixture of muriatic acid and solu- 
tion of tin, a stratum of water or concentrated muriatic 
acid and water, and a bar of tin is carefully inserted, crys- 
tals are immediately formed, but which, on account of the 
rapidity of their' formation, resemble more closely the 
flowers of chloride of ammonium; just as sal-ammoniac 
separates on slow crystallization in cubes, but when quickly 
evaporated produces the well-known arborescent figures. 
Above and beneath the spot where the crystals of tin 
separate, a thin black layer is formed, consisting of finely- 
divided copper with some tin when commercial tin is used, 
which always contains copper and some iron; when several 
such bars are connected, after the manner of Zamboni's 
battery, in adjacent glasses containing strata of tin solution 
and water, crystals are formed in each of the glasses ; but 
the black deposit appears at first always in one direction, 
being on one side of the bar of tin above, and upon the 
other side below the limit where the two liquids touch ; but 
after a time this sediment is formed both in the water and 
in the tin solution of each glass. 
Copper resembles tin in its behaviour, but it requires 
from eight to fourteen days to obtain regular octahedrons. 
When this electrical process is applied to the preparation 
of the protochloride of tin on a large scale, the ordinary 
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