INDUSTRIES DEPENDING ON ANIMAL PRODUCTS 



1687 



121 7 - On the Action of Alkalies and Acids on Rubber. — Eatox, b. j ., in The Agricultural 



Bulletin of the Federated Malay States, Vol. IV, No. 6, pp. 162-167. Singapore, March 1916. 



In a previous number of The Agricultural Bulletin (Vol. IV, N^. 2, Nov. 

 191 5), it was shown that solutions of caustic soda and of carbonate of soda 

 perceptibly hastened the vulcanisation of rubber obtained from planta- 

 tion Para rubber, Hevea brasiliensis. Since it had also been demonstrated 

 that vulcanisation is retarded by coagulation with excess of acetic acid, 

 the h^^pothesis was put forward that the acceleration produced b3' soda 

 was due to the neutralisation of the residual acid, and the production of 

 a more favourable medium for the organisms which are believed to cause 

 the more rapid vulcanisation. 



In order to see whether it was b}' direct chemical action on the rubber 

 that the alkalies hasten vulcanisation, further experiments were carried 

 out on finished rubbers, that is rubbers in a crepe form. In this way the 

 possibilit}^ of biological action was precluded b}^ the drv^ness of the sam- 

 ples. Two t^'pes of rubbers were chosen, a fast and a slow curing rubber. 

 The first 'had been prepared in the usual wa^' by crepeing slab rubber which 

 had been left standing at least six da^'s, and the second by crepeing fresh 

 coagulum on the day of coagulation. Solutions of caustic soda and caustic 

 potash were used. From the results of these esperiments the following 

 conclusions ma}' be drawn. 



i) The effect of soda and potash on rubber is to increase markedh- 

 the rate of vulcanisation. 



2) This effect is similar on slow and fast curing rubbers. 



3) The effect of alkalies appears, at present, to be due to chemical 

 action on some constituent of the rubber, but the evidence on this point is 

 still incomplete, and further researches are being carried out. 



4) Sulphuric and other mineral acids, potash alum and probably 

 other mineral salts retard vulcanisation. Their effect is greater with 

 quantities beyond the minimum necessarj^ for coagulation. 



5) The results obtained with mineral acids are important in con- 

 nection with estate practice in view of the probable substitution of sul- 

 phuric acid for acetic acid, and show that great care will have to be taken 

 in maintaining standard conditions, more so than in the case of acetic acid, 

 in which a moderate excess over the minimum necessary for coagulation 

 has little effect. 



The use of alkalies in the preparation of raw rubber has a deterio- 

 rating eft'ect on manufactured rubber goods. This entirely confirms the 

 deteriorating effect found to occur even on the raw rubber after keeping. 



1218 - New Dairy Industry Legislation in New South Wales, Australia. — o' Callaghan, 



M. A., in The Agricultural Gazette of New South Wales, Vol. XXVII, No. 6, pp. 409-414. 

 Sydney, June 2, 1916. 

 The " Dairj'- Industry Act " which was passed December 21, 1915 and 

 came into force June 21, 1916, amends the '" Dairy Supervision Act " of 

 1 901 and other acts dealing with the same matter. 



The new law regulates the manufacture, sale, storage, transit and 

 export of dairy produce, including margarine, the testing, mixing and 



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