22 ROYAL SOCIETY OF CANADA 
* 
in the drawn-out glass tubes, and the electric current, with a bell in the 
circuit, is employed to note the moment of fusion. (For details of pro- 
cess, see Journal of the Society of Chemical Industry, Sept., 1590.) In 
using this apparatus we found it practically impossible to obtain con- 
cordant results throughout a series of determinations owing to the ex- 
treme difficulty of introducing the same amount of mercury into the 
tube containing the fat. Thus, necessarily, the pressure upon the fat 
varies somewhat with each determination. Since slight differences of 
pressure affect materially the apparent melting point, we decided, if 
possible, to materially modify the method, avoiding the use of the 
drawn-out glass tube, and eliminating, as far as practicable, the factor 
of pressure. In this we were, in a large measure, successful. 
The apparatus is depicted in the accompanying illustration and 
may be described as follows:—(a) water-bath, (b) porcelain dish hold 
ing mercury, (c) small porcelain capsule also containing mercury, (d) 
thermometer reading to one-fifth degree, (e) cone, through which a wire 
closing the circuit passes. The disc of fat rests on the plane surface of 
the cone and insulates the exposed part of the connecting wire, (f ) bat- 
tery, (g) bell, (A) metal mould for making fat discs. 
The cone is conveniently made by passing a copper wire about ten 
inches in length through the stem of a small funnel and then pouring 
in melted sealing wax, keeping the wire central. The surface of the 
wax, after solidification, is smoothed with a file, the end of the copper 
wire projecting, say, 2 millimetres, beyond the plane. 
The circular mould (4) may be made from a piece of sheet lead. 
Its diameter should correspond with that of the mouth of ‘the cone (in- 
verted funnel) and have a thickness of, say, 4 millimetres. 
Having obtained the weight of the cone (e) with its projecting wire, 
a calculation is made to ascertain the diameter of a disc of fat of the 
thickness of the mould necessary to displace a volume of mercury equiva- 
lent to the weight of that of the filled cone. A circle of metal of such 
a diameter is then cut from the mould, which now presents the appear- 
ance of a washer. Its surfaces are amalgamated to prevent adhesion of 
the fat. 
Modus operandi: Fill the water-bath so that the surface of the 
porcelain dish (6) below the ring is in contact with the water. Pour 
mercury in (b) to the depth of about half an inch, and insert ther- 
mometer, as shown in illustration. Arrange the height of the capsule 
(c) so that the end of the copper wire from the cone dips about half an 
inch under the surface of the mercury, but taking care that it does not 
rest upon the bottom of the capsule. 
The disc of fat is made by placing the mould (A) onthe base of the 
cone (conveniently held inverted in the left hand) and filling the cen- 
tral space with the fat to be tested. This is most easily done by using 
