j^S PARA RUBBER. 



under vacuum the boiling point of water is reduced from 212 

 Fahr. to about 95 Fahr. 



THE PASSBURG VACUUM DRYING CHAMBERS. 



Passburg vacuum drying chambers are already in use on 

 several Para rubber plantations in Ceylon and Malaya. It is 

 interesting to note that two are in use at the Lanadron Estate 

 (of "block rubber" fame), Muar, Malay, one at the famous 

 Culloden Estate, Ceylon, and also at the Vallambrosa and 

 Highlands and Lowlands Estates. 



We are indebted to Mr J. Livingston, the British and 

 Colonial agent for Passburg drying apparatus, for the following 

 particulars in regard to them : 



" The vacuum drying chamber is designed to remove the 

 water rapidly and at low temperatures especially from such 

 materials as, on account of their sensitiveness to heat, could not 

 be dried by methods hitherto used without altering their chemical 

 composition, or required to be subjected to the drying process 

 for too long a time for practical and economical purposes, and 

 these difficulties increased when the articles to be dried were of 

 perishable nature. But also for such substances as can be dried 

 without injury under a higher temperature, this dryer can be 

 used with great saving in time, fuel, cost of plant, and working 

 expenses. 



" The dryer consists of a cast or wrought iron chamber or 

 cylinder which is closed hermetically at one or both ends 

 by doors. 



" The chamber contains a number of closed steam or heating 

 shelves or pipes (also for hot-water heating) arranged one above 

 the other, in which small pipes for the admission and exit of the 

 heating steam or hot water are fitted. The shelves are, as a 

 rule, made strong enough for a test pressure of 90 Ibs., the pipes 

 for a higher pressure. 



" On these are placed iron, copper, galvanised perforated iron 

 or earthenware trays, or trolleys, which contain the material that 

 is to be dried. After the door of the dryer, which is fitted with 

 an india-rubber joint, has been closed, a high vacuum of at least 

 28 inches of mercury or more is created by means of an air pump, 

 whilst exhaust or live steam or hot water passes through the 



