258 ANIMAL PROTEINS 



entering the sheds. This is accomplished by passing the 

 air through pipes from a refrigerator. When heated air 

 is used, it is stated by lyambert that the maximum tempe- 

 rature 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. lyambert 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. RideaTs 

 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 

 stiff er 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. 



