994 Scientific Intelligence. [Marcn, 
am not aware of any chemical book in which they are men- 
tioned. . 
The melting points of these metals, as determined by Mr. 
Creighton, are as follows: 
WON oe ae «cg + meetin ieee 
Wismiuit .”. ose. sas siees «ic eA ETO 
a aa br cage Pp ansye yt oa a 6 han eee 
Now the curious circumstance attending these metals is this : 
When they cool down to the melting pomt, bismuth imstantly 
sinks 8°, and immediately rises again; tin imstantly sinks 4°, 
and immediately rises again; while lead undergoes no change 
whatever, but remains stationary at 612° till the whole is 
congealed. 
It is well known that water in certain circumstances may be 
sunk down considerably below the freezing point without 
congealing ; but the mstant it begins to congeal, it rises 
again to 32°, at which it remains stationary till the whole is 
converted into ice. The subsidence of the bismuth and the tin 
is obviously analogous to that of the water, and the subsequent 
rise is doubtless owing to the commencement of congelation in 
these metals. The curious circumstance is, that each sinks a 
definite number of degrees, and that lead does not sink at all. 
I conceive that these phenomena depend upon the latent heat of 
these liquid bodies. When water is cooled down below its 
freezing point, it gives out a portion of its latent heat. The 
evolution of the latent heat, as it congeals, raises the temperature 
to 32°, and keeps it at that point till the whole water is converted 
into ice. Bismuth and tin, in like manner, may be cooled down 
several degrees below their point of congelation, and the heat 
they give out is a portion of their latent heat. When they begin 
to congeal, that portion which becomes solid gives out the whole 
of its latent heat, and this evolution keeps up the temperature at 
the melting point till the whole has congealed. But the latent 
heat of lead is much smaller than that of the other two metals. 
It seems this metal is incapable of parting with a portion of its 
latent heat. The whole of it escapes at once in proportion as 
the metal congeals: consequently the thermometer must 
remain stationary. The latent heat of these three metals, 
according to the experiments of Dr, Irvine, is as follows : 
Bismuth. ...... 550° It loses 1, of its latent heat. 
pF apt en ooh OUU It loses +45. 
Lead. .....:-+ 402 
III. Japan Copper. 
Bergman states the specific gravity of copper at 9°3243 (De 
Niccolo, Opusc. ii. 263), Cronstadt states the specifie gravity 
of Japan copper to be 9-000. X have never myself been able to 
