The cut or cast cakes are next placed upon network frames, and a series of such frames are placed on a bogey. The bogey is run along tram lines into the drying tunnel, through which air is forced or induced by a fan. Many such bogeys are, of course, passed into each tunnel, and as many tunnels as required may be constructed. Care is necessary to expose the cakes evenly to the action of the air. It is mostly necessary to warm the air at the inlet by means of steam pipes and so increase its drying power. This is especially necessary in winter or wet weather. In summer, however, it is often arranged that the air is cooled before entering the sheds. This is accomplished by passing the air through pipes from a refrigerator. When heated air is used, it is stated by Lambert that the maximum temperature should be 25.5° C. (78° F.); Rideal considers 21° C. (70° F.) should be the maximum. In all cases the drying power of the air is easily ascertained from a wet-and-dry bulb thermometer, and the amount of air passing along the shed from a wind gauge. Lambert states that drying normally occupies four to five days. The final product is still a gel, of course, and contains from 10 to 18 per cent. of water. It appears, however, very hard and solid. The dried cakes are removed from the frames and transferred to the warehouse, where they are sorted according to quality and packed in bags or tin-lined boxes. Some material is ground to powder. The network of the drying frames has been made from many materials. Cotton or string netting is very common, but is liable to sag and to get dirty. It also has a short life. Ordinary galvanized iron soon loses its galvanizing cover, and the iron then is liable to rust. Attempts have been made to use sheet zinc and other alloys, which are cut or punched into nets with square or diamond-shaped holes. These were found to warp and break. Rideal's conclusion, which is confirmed by the general experience, is that the best material is a heavily galvanized iron wire netting. He suggests that it should have 15 to 25 per cent. of its weight of zinc, and that it should be strengthened by stiffer ribs arranged both longitudinally and transversely. Many attempts have been made, and many patents taken out, with the object of making the cooling, cutting, and drying processes as continuous and as quick as possible, and with a view to saving labour, which is rather costly at this stage. These attempts, however, have only met with indifferent success. A common idea is that a continuous supply should fall upon a revolving appliance, and be instantly congealed in a thin state, which last lends itself to more rapid desiccation. Vacuum drying has also been attempted. REFERENCES. "Glue and Glue Testing," S. Rideal, D.Sc., pp. 68-74. "Glue, Gelatine, and Allied Products," T. Lambert, pp. 30-35. _Chem. Zeit._, 1911, 85, 17 (Cavalier). PATENTS. Eng. Patent (1894) 11,426 (Hewitt).