THE DETERMINATION OF CANE SUGAR 



501 



which differs only in details from that employed by Spencer, to whom the 

 routine is due, is shown in Fig. 332. A is a cylindrical container 6 ins. 

 diameter by 10 ins. high, provided with a wide flange B at the top and per- 

 forated at the side near the bottom as indicated at C. D is a cylindrical 

 vessel with a flange E corresponding to the flange B. At the bottom of 

 this container is located a hot element, F, which may be either a steam 

 coil, or an electrically heated resistance. The bottom of the vessel D is 

 perforated. Across the top of the bagasse container is laid a cover G, in 

 which is inserted a tube H, allowing of connection to a source of vacuum. 

 The three parts B, E, and G may be drawn together by means of clamps K, 

 and a tight joint secured. On making connection to the source of vacuum, 

 a current of hot air following the direction shown by the arrows is aspirated 



FIG. 334 



through the bagasse. The size of container given will hold 1,000 grams of 

 bagasse and drying wilfbe complete in two hours. 



Vacuum Oven. The vacuum ovens usually found in sugar laboratories 

 are essentially of the pattern devised by Carr 8 . They are obtainable from 

 dealers, but more conveniently and at less cost can be constructed in the 

 field. One made by the writer is shown in section in Fig. 333, while a 

 perspective view is given in Fig. 334. It consists of a piece of 6-inch copper 

 pipe 9 inches long. A chamber b is arranged round the pipe, into which 

 is conducted exhaust steam, the condensed water being carried away by 

 the pipe c. The vacuum chamber of the oven is connected to the last cell 

 of the evaporator by a half-inch pipe d. The door of the oven is a 

 stiff iron or steel plate h, on which is arranged a washer of some soft 

 material such as asbestos packing. The external pressure keeps the door 

 in place and thumb-screws are unnecessary. A pipe g serves to break the 

 vacuum. A vacuum gauge and thermometer are shown at/ and e. 



The arrangements specifically mentioned here may be modified by 

 filling the space between the oven and jacket with water and heating by a 



