At present there would seem to be only two methods which are successful in the prevention of a "rusty" appearance in the dry rubber. Singularly enough, the two methods appear to be directly opposed in principle. They are: A. THE HOT-WATER TREATMENT.--This method has been in constant use on estates which have old trees giving rich latices. These latices are always diluted to a uniform standard daily. Some estates which formerly suffered from the defect now experience no difficulty, and in other instances, where no complaint has yet been received, the treatment has been followed consistently. (1) After the sheets have been through the marking rolls, it is the general custom to allow them to drip for about three hours. This interval is really excessive for the mere draining away of the surface water, but as a rule it is just sufficient to allow a portion of the liquid retained in the rubber to exude. It has been shown that this liquid may contain some protein matter in solution. Sometimes in the case of thick sheets which have been subjected to pressure so much of this matter is exuded as to form a thin surface slime which is distinctly evident to the touch. If the sheets are allowed to hang overnight, the presence of the exuded matter may be detected also by its odour. (2) Obviously, any method which will remove this surface film should be of great benefit. It is found that the best results are obtained by allowing sheets to drip for about two hours, and then placing them in hot water for five or ten minutes. The water should be hot as the hand can conveniently bear, and it need hardly be pointed out that the same water should not be used for the whole day's output. For preference there should be three or four vessels, each capable of holding a fair proportion of the total number of sheets, and frequent changes of hot water. (3) After remaining in the hot water for the period mentioned, the sheets are removed singly, each one being surface washed or swilled as it is taken out.