THE CHEMISTRY OF THE HIVE. 
593 
wax, when solidified, may be easily removed. These 
should be also slightly oiled, to prevent adhesion. 
The receiver should be placed on a cooler part of 
the stove, or be in some way gently heated during 
the process, while hot water, 2in. or 3in. deep, should 
be placed within it at starting ; by this means the 
wax will be kept fluid, and the impurities will settle 
to the bottom of it, from which they may be sliced 
off when it has thoroughly set. These appliances save 
labour, and are very cleanly, altogether preventing the 
danger of boiling over, so likely to occur where combs 
are placed in water, as the molten, swimming wax in 
this case impedes the escape of the steam. 
Wax may also be obtained by the solar extractor, 
which depends for its action upon the curious fact that 
glass is diathermanous for heat from luminous rays, and 
athermanous for obscure rays — i.e., heat direct from the 
sun passes through glass easily, but by contact with 
material substances it is changed into obscure, or 
non-luminous, heat, which, as such, cannot re-traverse 
the glass. The accumulated temperature of green- 
houses, if exposed to direct sunlight, is thus accounted 
for, the heat passing into the house, but being unable 
to pass out again. The solar extractor is of most simple 
structure, and is, practically, a box having a sheet, or two 
or more sheets, of glass, one within the other, for its 
lid. Beneath comes the perforated bed, on which 
rest the combs. The wax drops through the per- 
forations, and must be duly received below. It is 
sometimes mounted on a leg-stand with a universal 
joint, so that the glass may be presented to the sun 
wherever he may be situated. As it works dry, it 
VOL. II. 2 Q 
