RUBBER 669 



by the Department. Towards the end of last year and 

 early during the present year (1914) the experiments were 

 carried a step further and a number of shallow trays 

 utilized for the purpose in a " Jackson " smoking cabinet., 

 which is essentially a small smoke-house with walls and 

 roof of galvanized iron, with a small furnace below in 

 which compressed coconut fibre, especially treated by 

 the inventor, is burnt. The fumes are very rich in creo- 

 sotic vapours and cause a very rapid smoked appearance 

 in ordinary sheet and crepe rubber. It was found possible 

 to coagulate layers representing a pint of pure latex in 

 trays 24 in. by 9 in. in twenty-four hours or less. These 

 trays should be constructed not more than I in. deep and 

 placed in tiers with about J in. space between each tier 

 and J to i in. space between each tray in any one tier, 

 in order to give sufficient space for the smoke to pass. 

 If the space thus left is insufficient for a good draught 

 an exhaust fan could be employed. Pure latex containing 

 25 to 30 per cent, of dry rubber, or, say, 2*5 to 3 Ib. 

 per gallon, should be used, as there is less water to 

 evaporate and coagulation takes place more readily. The 

 capacity of chamber required can easily be calculated for 

 any daily yield of latex. Thus the actual cubic content 

 required per pint of latex on the above assumption would 

 be 480 cub. in. with trays I in. deep, allowing I in. 

 space between each tier of trays and I in. between 

 each tray, or, say, 2.\ cub. ft. per gallon of latex, i.e., 

 a chamber 5 ft. square and 9 ft. to the eaves would be 

 sufficient for 100 gals., or, say, 300 Ib. of dry rubber 

 per day. A number of small cabinets would probably 

 be preferable to one large chamber. It may be found 

 possible to coagulate a deeper layer of latex than is 

 represented by a gallon of latex spread over an< area of 

 12 sq. ft., in which case a large volume of latex could 

 be treated at the same time in a chamber of the above 

 size. 



Each layer of latex in a tray is smoked for twenty-four 

 hours or less, and the following day a similar layer is 

 added, the addition being continued till the trays are full, 

 which takes from one to two weeks, according to the 

 depth of tray used. 



