ME. GEOEGE GOEE ON ELUOEIDE OF SIEVES. 
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Fluoride of silver in a platinum crucible within a heated cast-iron muffle with a bar 
of zinc near the crucible, melted at a temperature much below redness, and at exactly 
the same time as the zinc ; its fusion-point therefore is about 434° C. 
50 grains of the salt was melted in a platinum crucible ; 20 grains of scraps of pla- 
tinum was now added, and the lower end of the retort (enclosed within a glass test- 
tube) heated in a bath of melted zinc during half an hour to a temperature varying both 
above and below its fusion-point, the exit-tube of the retort being connected with a 
glass receiver over mercury. Only a trace of gas was evolved, and the retort and its con- 
tents lost only '05 grain in weight. The salt therefore is not decomposed by heat alone 
at the temperature of melting zinc. According to Fremy also (Chemist, New Series, 
vol. i. pp. 556 & 557) the anhydrous salt is undecomp osable by heat. 
In some cases of evaporation of fluorides I have used the following arrangement to 
prevent the products of combustion from the gas-flame coming into contact with the 
substances. It consists of a triangular sheet-iron cap, fig. 1, without a bottom, fitting 
over the top of a common iron tripod. In the upper surface of the cap is a large hole 
A, to receive the evaporating dish. The cap has a short chimney, B, and two flaps of 
sheet iron, C, C, with hinges to admit of a gas-burner being placed beneath. 
In other experiments in which tubes were heated to redness, I have employed a row 
of Bunsen’s burners (fig. 2), with a moveable table A A of sheet iron fixed to them at any 
desired height by the screws B, B. The table was for the purpose of supporting the 
tube, which lay in two notches in its edges in the direction C C ; it was also used for 
supporting notched plates of fireclay to increase the heat. To fix the tube securely to 
the table, two peculiar hooked-shaped pieces of iron, provided with screws, were em- 
ployed, as shown in fig. 3. 
In numerous experiments requiring the fusion of fluorides See., I have employed a 
