The glue-boiler should, in all cases, be prepared to undertake the preparation of the glue stock himself. The following arrangements are required for the purpose:
Let us assume that the glue factory is located on a stream of water. In the immediate neighborhood of the stream a sufficient number of pits to prepare all the glue stock used, each about 6½ feet deep and 6½ to 10 feet in diameter, and lined with cement, are so arranged that their bottoms are about 3 to 3½ feet above the level of the water. They are supplied with water by means of a pipe line connecting one with the other. Each pit is provided with a discharge pipe to draw off the dirty water.
As the glue-stock, before undergoing other operations, has to be freed from the lime by washing with water, the simplest plan is to place the limed stock in nets or wicker baskets suspended in running water by means of a traveling crane or other contrivance erected on the bank of the stream. This elementary method, however, is open to several disadvantages, as it fouls a large volume of water and may lead to legal interference, and its very simplicity is apt to lead to neglect of precautions, such as brushing away solid particles of lime or softened animal matters. Further, the great quantities of water carry off small pieces of glue-stock and fat, if catch-basins are not provided sufficiently large to allow fat, glue-stock, hair and lime to separate from the water.
The object is better accomplished and in a shorter time by the use of a washing drum. This consists of a perforated iron cylinder about 6 feet in diameter and 4 feet in length, and open on both ends. Around the inside of the cylinder are fixed a number of wooden shelves 6 inches broad, which, as the cylinder revolves, carry the glue-stock partly round, ultimately falling to the bottom again, the movement dashing it about under a spray of water. In the cylinder is also arranged an iron plate supported by stays from the outside. While the washing is in operation the plate is turned perpendicular; on completion it is brought to a horizontal position, forming a table, on which the glue-stock falls, and the latter is then removed to a hand-press to squeeze out the water. The washed stock is then removed to the drying ground, which should be in a sunny and airy location, and provided with an inclined floor of planks or cement so arranged as to allow of the admittance of air from beneath.
As it is well known that small quantities of liquid, frequently renewed and thoroughly drained off each time, effect the most complete and economical washing, and in the shortest time, S. Rideal recommends the use of pits or vats with proper arrangements for stirring, draining and inspection. The lime scum from the pits can be used in the manufacture of fertilizers.
The glue-stock washer shown in Figs. 2 to 5, is the invention of W. A. Hoeveler (American patent), and it relates to the construction of apparatus for washing glue-stock.
In apparatus for this purpose the stock is very commonly damaged by being broken up too much, and considerable loss results, besides, from the fact that the small particles are allowed to escape with the wash-water. By the present construction and arrangement these defects are remedied and other advantages derived.
Fig. 2 is a transverse vertical section on line x-x of Fig. 3 of this apparatus;
Fig. 2.
