MANUFACTURE OF CASEIN. 11 



stacked trays freely through it. Many tunnels are made 31 or 32 

 inches wide to accommodate the 30-inch-square drying trays which 

 can be purchased ready-made. The tunnels used in our experiments 

 were 21 inches wide (fig. 2). A double-tunnel drier, 22 feet long, 

 5 feet high, and each tunnel 24 inches wide, when filled with drying 

 trays will hold the casein from 20,000 pounds of buttermilk. The 

 driers can be made of any length and height but it is advisable to 

 have them high enough to allow a man to walk in without incon- 

 venience when pushing the trays in or out. Full- width doors are 

 placed on each end of the tunnels, so that the trucks stacked full of 

 trays may be pushed in at one end and out at the other, which facili- 

 tates and systematizes the work. The cost of a drying tunnel can be 

 ascertained by considering the type of construction and the price of 

 material and labor available in the locality. 



BLOWEB AND HEATING APPAEATUS. 



A low-pressure blower of sufficient capacity to provide a large 

 volume of heated air over the ground curd is required. jSTo exact 

 figures as to the cost of a blower can be given. One of the casein 

 jobbers quotes a price of $35 on a blower and $50 for a heater which 

 has sufficient radiating surface to heat the air to the required temper- 

 ature. The additional expense of installing the apparatus, supposed 

 to have a capacity for drying the casein from 15,000 pounds of milk 

 daily, should also be considered. It may be possible to make a pipe 

 heater at the factory more cheaply than it can be purchased, but if 

 the best results are to be obtained care must be taken to have the 

 proper radiating surface. 



DEYING TEAYS AND TETTCKS. 



Satisfactory drying trays of the desired size can be made of -|-inch 

 square strips and galvanized screening. A rectangular frame is made 

 of the strips, Avhich are mortised and glued at the corners. Another 

 strip is mortised lengthwise of the frame. Galvanized screening, 

 16 meshes to the inch, such as is used for windows and doors, is 

 tacked to one side of the frame, after which ^-inch by f-inch strips 

 are placed over the screen, flush with the lengthwise strip, and fas- 

 tened with screws. The three strips forming the bottom of the tray 

 allow a free circulation of air through the stacked trays, and in 

 addition materially strengthen it. Canvas or unbleached muslin 

 used on the bottom tray of each truck, in place of the screening, serves 

 to catch the fine particles of dried casein that drop through the 

 upper trays. With galvanized-wire screening at the prices that 

 prevailed in 1911, when the experimental equipment was installed, 

 the 23 by 30 inch trays may be made for $7 a dozen and the 30 by 30 

 inch trays for about $9 a dozen. 



