Oums, Resins, 



468 



[Dec. 1906. 



DEMONSTRATION IN THE TREATMENT OP LATEX. 



After going through the plantation the party returned to the Laboratory 

 where Mr. Wright gave a brief demonstration in the treatment of latex. Mr. 

 Wright said :— We had all heard lately about the difference in the physical pro- 

 perties between rubber obtained from five, six and thirty year-old trees. I have 

 here samples from trees 29h years. [The biscuits were handed round and tested and 

 proved to be of excellent strength and resiliency.] These have all been treated with 

 a little formalin. They are not smoked. We have now gone through practically 

 every process at Peradeniya and Henaratgoda. You have seen the trees that have 

 been tapped and got information regarding the yields obtained, &c, and you have 

 seen every development at Peradeniya in the manufacture from the latex. There is 

 very little of interest left to go over except to describe a few of the characteristics 

 of fresh latex. 



Mr, Wright then experimented with a quantity of latex to ascertain the 

 amount of acid required to coagulate. He remarked that the latex, as it came from 

 the field, or as it is issued from the tree, was either neutral or a little alkaline. Mr 

 Wright dipped some red and blue litmus paper in the latex and asked them to notice 

 that the blue remained blue and the red remained nearly the same It was almost a 

 neutral solution. So long as it remained in that condition coagulation would not 

 take place. If they wanted to effect coagulation they must either let the latex stand 

 to allow the acids to develop or use some acid. Washing eliminated a certain 

 portion of the acid added, but if they determined the quantity by means of litmus 

 paper, he thought it would do away with a good many cf the objections that were 

 put forward by people at home to the use of these reagents. The point was to 

 add just sufficient acetic acid to neutralise the latex, until it was just on the 

 turning point and then allow it to settle. 



Mr. RYAN :— What proportion of acid ? 



Mr. Wright :— You never know the proportion beforehand, because the 

 composition of the latex varies very much. 



Mr. Wright then demonstrated with blue papers adding acid until they 

 began to get red. 



Mr. Cameron :— May I ask what proportion of water is in the latex ? 



Mr. Wright :— A very large proportion. Pure water makes no difference 

 to the rubber. Many people have used impure water which has pre-disposed the 

 rubber to tackiness. 



Continuing, Mr. Wright said that in future their programme would be 

 considerably changed. They had now arrived at the stage when they could 

 despatch their latex to Peradeniya, Formerly the Foreman prepared the biscuits 

 at Henaratgoda. Now their latex could be sent to Peradeniya and manufactured 

 there so that they hoped to make good samples of rubber. 



The Hon. E. Fielding :— How do you preserve it on the way ? 

 Mr. Wright :— By the addition of ammonia or formalin. 

 The Hon. E. Fielding :— Does it matter how much ? 



Mr. Wright ;— You soon get to know how much you want. It depends a 

 great deal on the amount of water you add and acidity present. 



Mr. Parkinson !— Do you ever find that for a natural coagulation it takes 

 longer when you have a large quantity of water ? , 



Mr. Wright i— I cannot say I have had that experience. Have you ? 



Mr. Parkinson £—1 have found it so., and I think you will find it so, 



Mr* Ryan :— My experience is the same as Mr. Parkinson's* 



