Miscellanies. 371 
of soda, the manganese was precipitated, and then dissolved in nitric 
acid, and again ignited. In two grammes of the coal was found 
0.108 oz. of iron, and 0.034 protoxide of manganese. 
11. On the Expansion of Bismuth and its Alloys during conge- 
lation.—(Prof. Marx, of Brunswick.)—Bismuth is known to be a 
very remarkable instance of apparent exception from the general 
tule, that fluids contract when becoming solid ; and it corresponds 
with water in this respect also, that it communicates this property to 
other bodies, particularly metals, if it forms a certain portion of the 
alloy. Where the maximum of density lies, and in what degree the 
volume of the solid metal exceeds that of the fused, has, as far as we 
know, not yet been ascertained ; but the former is probably very near 
the point of congelation ; and of the latter, an approximate evaluation 
may, according to Prof. Marx, be made in the following manner. If 
a quantity of bismuth be fused in an iron spoon or a glass tube, and 
then removed from the fire, the mass remains fluid for some time ; 
it then congeals at the surface, but after the whole seems to be quite 
solid, all at once a large quantity of globular masses protrude from 
the surface, which are always proportional to the quantity of the met- 
al employed, and may perhaps serve to determine the quantity of the 
expansion : this was according to several experiments of Prof. Marx, 
found to be about ;!, of the weight of the whole, and consequently 
less than a third of the expansion of water. The force with which 
bismuth expands is so considerable as to break glass tubes in which 
the fused metal is allowed to cool; thus, if a thermometer tube is 
plunged into fused bismuth, and then filled with it by sucking the me- 
tal up, it always breaks within a short time, with a loud cracking, and 
in several directions, but mostly longitudinally, so as to form long 
parallel glass fibres. For the success of this experiment, It 1s, how- 
ever, necessary to make the column of metal long enough, otherwise 
its longitudinal increase will cancel the expansion. , 
12. Bismuth, Tin and Lead.—The alloy B*T'L", is known 
for its great fusibility, the point of fusion being below 180° F, On be- 
Coming solid, the surface is rather depressed, and the mass seems ac- 
_ cordingly to contract ; and in most cases, however, the thermometer 
tubes burst longitudinally a long time after the mass has become solid. 
he tin seems accordingly, ~under these circumstances, to overbal- 
ance the equalizing force of lead. 
