134 THE MANUFACTURE OF GLUE. 
two inches thick. The slabs are carried on piles to the drying- houses, 
where they are laid upon network frames, a thorough draught of air being 
constantly maintained over their surface, by the sides of the shed being 
open to the four winds of heaven. The slices are turned from time to 
time, and gradually dry into the hard compact form in which glue enters 
the market. 
This part of the process is a most critical one, a slight variation in 
temperature being sufficient to spoil a whole batch in a very short time. 
In winter, a sudden sharp frost will do a hundred pounds worth of 
damage in a few hours, by freezing the soft cakes, and cracking them 
into an infinite number of fissures. A sudden rise in temperature will 
have a disastrous effect from the opposite cause. The rise in the heat 
will sometimes increase the solvent power of the water contained in the 
glue to such an extent, that the cakes partially liquify and drop through 
the meshes of the network. Again, in damp, foggy weather, a sort of 
fungoid vegetation is apt to form on the surface of the cakes, destroying 
the transparency of the glue, and rendering it unsaleable. Several 
remedies have been tried for this latter misfortune, but none appear to 
answer perfectly. 
To transform glue into the gelatine of the shops, it is simply neces- 
sary to dissolve it in water and allow it to settle. Clarifying agents are 
also used to destroy the last vestiges of colour. 
There is almost as much fashion in glue as there is in bonnets — 
workmen showing themselves absurdly ignorant and capricious in their 
choice of various forms of glue. We say forms designedly, for many 
carpenters are not aware of the fact that the best glue is that which is 
made with the greatest care, whether in London, Salisbury, or Scotland ; 
whether it is in long, broad, or thin cakes : has a piece of string run 
throught it, or is destitute of that appendage. Others, again, have a 
fancy that the darkest glue is the strongest ; but this is also a decided 
error. Thus, the principal difference between " Scotch " and " London " 
glue is, that the former is cut a little narrower than the latter, and has 
a string run through several cakes. 
Size is a weak solution of glue allowed to gelatinize. About size, 
too, the most erroneous notions have obtained credence among work- 
men, most of whom fancy that the darkest is necessarily the best. This 
absurd notion has led certain manufacturers to adopt artificial means of 
colouring their size. 
The cakes being dry and hard, they are taken off the nets, the 
marks made by the meshes appearing in cross-barred impression on the 
surface. If the glue has caught the " mildew," or has become dusty, each 
cake is scrubbed with a brush and hot water, to give it a clean and 
polished appearance. The cakes are then stacked in stores, in which 
every particle of moisture is driven out of them by artificial heat. 
Such is the simple process of glue-making, the real secret of success 
in which is care and cleanliness. — * The Ironmonger.' 
