66 PARA RUBBER. 



has been tapped the drip is allowed to commence. By these means 

 the latex is to a great extent prevented from drying up on the stem 

 and is carried rapidly towards the base ; the latex tubes not being 

 blocked by the coagulated substances continue to give forth the 

 latex for a long period. It is claimed that this invention will greatly 

 reduce the amount of scrap, and that the laticiferous tubes are more 

 nearly emptied by its adoption. 



It is certainly an advantage to be able to secure, when necessary, 

 the latex in such a state that it will remain in a liquid condition 

 until the formalin or ammonia is driven off. The accompanying 

 sketches are, by favour of the patentee, here reproduced on Plate 15. 



The above refers to the more complex type of drip-tin, but 

 several others designed on an improved and simpler plan and more 

 suitable for coolies have already been made by the same patentee. 



Keeping the Latex Liquid and Settling Tanks. 



On small estates where few and widely-scattered trees are being- 

 tapped the planter is often compelled to resort to the production of 

 rubber on a small scale ; this frequently involves a daily repetition 

 of the same process and much petty hand labour. The latex can, 

 however, be kept in a liquid condition for several days or even weeks, 

 without doing any harm to the finished product, and the rubber 

 can be manufactured on a big scale when a sufficient quantity of 

 latex has been accumulated. 



The latex can be kept in the liquid condition by the addition of 

 ammonia, formalin, sodium carbonate, and any alkaline chemical 

 which is readily soluble in cold water. It is better to use either 

 ammonia or formalin and to avoid any of the mineral salts ; the 

 former can be readily removed and may even escape on exposure to 

 the air in the ordinary processes of manufacture. 



In one invention, patented by Brown, the latex is kept in covered 

 settling tanks supplied with (1) a drip-tin apparatus filled with 

 chemicals to retain the milk in an alkaline condition, and (2) with a 

 paddle to keep the latex in motion. If a receptacle containing 

 ammonia is exposed to the air, the reagent will evaporate and the 

 latex coagulate within a few days. If, however, the receptacles are 

 covered or sealed, the ammonia cannot easily escape and the latex 

 can be accumulated in a liquid state indefinitely. 



Formalin has a similar effect, as it stops putrefaction and 

 therefore prevents the development of acidity. The ammonia 

 probably neutralizes the acids as they are formed and thus maintains 

 the latex in an akaline or neutral state, and thereby prevents the 

 precipitation of the proteid matter. By the use of such reagents 

 and apparatus a great saving of labour may be effected. 



The Editor of the India Rubber Journal has recently reviewed a 

 translation of a privately circulated French pamphlet, on the sub- 

 ject of exporting the latex in a liquid condition in order to allow the 

 manufacturer to prepare his materials at the first coagulation. 



