THE 



TROPICAL AGRICULTURIST 



AND 



MAGAZINE OF THE 



CEYLON AGRICULTURAL SOCIETY. 



Vol. XXXIII. COLOMBO, JULY 15th, 1909, No. 1. 



Reviews, 



TACKY RUBBER. 



[Ueber einige einleitende Versuehe zur 

 Klarung der Ursache des Leimigwerdens 

 voa Rohgummi. Von. Dr. D. Spenee 

 (Universitab Liverpool). Souder-abdruck 

 aus Zeitschrift fiir Chemie und Industrie 

 der Kolloide, Bd. IV., Heft 2 und 3.] 



The author has for some months been 

 engaged in the study of the causes of 

 tackiness in rubber, and has issued a 

 preliminary account of some of his 

 experiments. He refers rather causti- 

 cally to the various theories which have 

 been propounded in explanation of this 

 phenomenon, e.g., oxidation, putrefac- 

 tion, the action of Bacteria, and 

 Enzymes, and points out that none of 

 these is based on any scientific experi- 

 ment, He agrees with Professor 

 Bertrand, who read a paper on the 

 subject at the Rubber Exhibition of 

 1908, that Bacteria cannot be the direct 

 cause of tackiness. Unfortunately, the 

 Report of these lectures is not yet 

 available. 



"Thanks to the experimental researches 

 of Bertrand, we have no longer 

 much to fear from Bacteria with regard 

 to tackiness. To pacify those who still 

 pin their faith to the theory of the 

 bacterial origin of tackiness, it may be 

 pointed out that it remains to be proved 

 whether bacteria have not perhaps an 

 indirect influence, in so far that they 



may possibly create a suitable medium 

 in which tackiness can afterwards occur. 

 I refer here especially to the formation 

 of acid substances through the action of 

 bacteria on the protein substances and 

 their constituent carbohydrates in raw 

 rubber. To me it is quite unthinkable 

 that bacteria can have any direct action 

 upon the actual caoutchouc, but it is 

 however imaginable that they might 

 exert a small indirect influence in giving 

 rise to conditions which favour tacki- 

 ness. This possibility appears to have 

 been hitherto totally overlooked, aud I 

 bring it forward since it indicates the 

 need of further investigations into the 

 action of bacteria — not on caoutchouc 

 but — in caoutchouc," 



" For the benefit of those who, in 

 spite of the lack of logical experimental 

 evidence, believe in the enzyme theory 

 of tackiness, I may point out that I have 

 taken the trouble to prepare a large 

 number of rubbers from latices which 

 were freed from enzymes as far as 

 possible, and that, even in those pre- 

 parations to which I had given the 

 greatest conceivable care in the removal 

 of the enzyme before coagulation, I have 

 several times observed exceptionally 

 well-developed tackiness. Consequently 

 the enzyme is not directly concerned in 

 the production of tackiness, though 

 naturally here again the possibility of 

 an indirect action because of the pre- 

 sence of the enzyme in the rubber must 

 be taken into consideration. It can be 



