10 



BULLETIN 661, U. S. DEPARTMENT OF AfiRICULTTJRE. 



trucks to hold the trays, and the curd mill. Several creameries may 



combine to maintain a central drying plant and ship their green 

 curd to the plant for drying; this is advisable if each plant, because 

 of the small quantity of curd handled, can not afford a complete 

 equipment. 



TUNNEL DRIEK. 



The best type of drier is made of tongue-and-groove boards nailed 

 both sides of the studding, the space between being filled preferably 



Fig. 2. — Well-constructed double-tunnel drier lined with galvanized iron. Two large 

 pipes take off the heated air after it has passed over the casein. Steam radiator for 

 heating the air shown at top and farther end of tunnel. 



with dry sawdust or other insulating material. It is advisable to 

 line the tunnels with galvanized iron if they are to be used continu- 

 ously, as the large volume of heated air passing through them dries 

 the boards out to a considerable extent. A cheaper type of construc- 

 tion consists in nailing tongue-and-groove boards on only one side 

 of the studding. While, because of leaks and other losses, that kind 

 of drier is not so economical of the heated air, it gives satisfactory 

 results. It is more economical of both space and construction to 

 have a double-tunnel drier built along the wall where it will be least 

 in the way. The tunnel should be made one inch wider than the 

 trucks and drying trays, to allow sufficient room for moving the 



