44 SCALE PESTS OF COFFEE 



was difficult and required supervision if the mixture was to 

 be properly made. The correct proportions of the ingredi- 

 ents, and the order in which they were to be added, were 

 some of the important details which could not be entrusted 

 to coolies. The mixture contained, as already stated, 

 one pound of soda to a pound of each of the other ingre- 

 dients. It was soon found that this quantity of soda was 

 excessive and could be reduced safely to eight ounces. As 

 a matter of fact, this is the quantity usually given in 

 formulffi for the preparation of resin washes. With the 

 introduction of soda ash (anhydrous sodium carbonate) 

 this quantity could be reduced to four ounces. The 

 excessive quantity of soda originally used served no 

 useful purpose. On the other hand, experiments conduct- 

 ed by the Department showed that a spray mixture with 

 this quantity of soda had a very. much more markedly 

 scorching effect on the leaves than had mixtures, with a 

 smaller quantity of soda. 



To avoid the difficulties enumerated above and to 

 reduce the cost, it was suggested to Mr. A. K. Menon, the 

 Oil Chemist and Soap Expert of the Madras Fisheries 

 Bureau, that a new insecticide should be made out of the 

 fish oil manufactured in large quantities on the west 

 coast. He had considerable experience of the preparation 

 of soaps while in England and was engaged in experi- 

 mental work at the Tata Kesearch Institute at the time. 

 Mr. Menon readily took up the suggestion, more especi- 

 ally as this promised to provide a means of disposal of 

 the oil for which there was, at the time, no profitable 

 market. A new soap was made from fish oil to which 

 resin was added according to the formula given. The 

 mixture thus obtained could be easily dissolved in cold 

 water and sprayed. The first samples of the new insecti- 

 cide and the soaps were taken to one of the estates near 

 Chikkenhalli and experiments on spraying were conducted 

 by the junior author early in 1914. The following is a 

 summary of the report of experiments conducted by him 

 from 1st May to 7th of June, 19H:— 



1. " Four different strengths of the emulsion were 

 tried. 



(a) 1 lb. of the insecticide per kerosene tin (4 gals.) 



(b) 2 lbs. 



(c) 3 lbs. „ „ 

 • (d) 4 lbs. 



