[31] “Preparation and Vulcanisation of Plantation Rubber” (Eaton, Grantham, and Day), Bulletin No. 27, F.M.S. Department of Agriculture, 1918.
The second claim has been the subject of much controversy. Experiments made on estates under the supervision of, or in the absence of, the patentees have given conflicting results. When varying factors have been eliminated, the general conclusion was that no increase in weight of rubber was obtained.
Private laboratory investigations led to a similar verdict, and Eaton[32] records a confirmatory finding. More recently the claims made for the process were investigated in Java[33] under varying conditions. Three series of experiments were made:
[32] Ibid.
[33] “Archief voor de Rubbercultuur” (De Vries and Spoon), Central Rubber Station, Java, May, 1921.
(1) During the rainy monsoon and at a height of 1,800 feet.
(2) During the dry monsoon on a low-country estate.
(3) In the experimental gardens at Buitenzorg during bright sunny weather and the most favourable conditions.
The agents used were (a) a mixture of alcohol and fusel oil, (b) alcohol and petrol (benzene).
In these experiments no advantage in weight of rubber was obtained by the Ilcken-Down process, and it would thus appear that the principal claim fails to be substantiated.