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XXXIII. Conductibility of Mercury and Amalgams. By F. Ceace-Calveet, Esq.., F.C.8., 
Mem. Boy. Acad, of Turin, &c. Ac., and Eichaed Johnson, Esq., F.C.S., Mem. Phil. 
Soc. of Manchester. Communicated hy Professor Stokes, Sec. B.S. 
Eeceived April 14, — Eead May 19, 1859. 
We have the honour to lay before the Eoyal Society the second part of our paper on 
the Eelative Powers of Metals, Alloys, and Amalgams to conduct Heat. Having in our 
former paper described our experiments upon metals and their alloys, we now give the 
results obtained vdth mercury and amalgams. 
The method followed in the investigations described in this paper is the same as that 
detailed in oiu’ former one. When the amalgams were solid, we melted and cast them 
in square bars, and filed them down until they were 1 c. m. square and 6 c. m. long ; 
but when the amalgam was fluid, we introduced it into the small iron box (see former 
paper. Philosophical Transactions for 1858, p. 354) and determined its conducting 
power. 
Before stating the results obtained with amalgams made of pure metals in equivalent 
and multiple quantities, we wish to draw attention to the remarkable manner in which 
heat is conducted by mercury. 
But before entering into the details of our experiments, it is necessary that we should 
state that, having completed our researches some time since, we forwarded the results 
to the Jimior Secretary, Professor G. G. Stokes, for presentation, when he kindly 
made to us the remark that mercury might be a worse conductor than we had found it 
to be, and that the means adopted by us were not sufficient to prevent the mass of 
mercury in the httle Iron box becommg heated through currents ; and lie suggested that 
we should tilt our apparatus, and ascertain what would be the influence of various angles 
on the conductibility of mercury as determined by our method. 
By following out this suggestion, we were led to the interesting discovery that mercury 
is the worst conducting metal known, when the heat is so applied as to prevent the 
mass becoming heated by currents. 
To attain this object, we filled our little iron box with pure mercury, and having 
ascertained by its weight that it was quite full, we introduced 1 cub. cent, of it into 
each of the wdcanized caoutchouc vessels ; we then poured 50 cub. cent, of cold water, 
and waited until it had arrived at the temperature of the atmosphere of the laboratory. 
The larger vessel was in its turn filled with 200 cub. cent, of water at 90°. The apparatus 
was so arranged that the large vessel, or the source of heat, was placed perpendicularly 
over the small one. The temperature of the large one was maintained at 90° during 
