9 



(4) The general conditions of soil-fertility are closely connected with 



those of nitrification, good cultivation promotes efficient nitri- 

 fication. 



(5) The rate of nitrification of ammonia corresponds with the re- 



quirements of plants and during the growing season this 

 change takes place quite as fast as is good for the plant. 



INSTRUCTIONS FOR THE USE OF CARBON BI- 

 SULPHIDE AS AN INSECTICIDE. 



By H. H. Cousins, M.A. (Oxon), F.C.S. 

 Introduction. 



Carbon bisulphide is the most efficient insecticide known for the 

 treatment of insects destructive of stored grains, root-boring pests in 

 the soil and insects injurious to stored tobacco, clothing and books. 



It is also of great value for the destruction of insects in granaries and 

 houses where these have become a serious pest 



Owing to its high volat lity and the extremely inflammable nature 

 ,of its vapour, carbon bisulphide requires special precautions in its 

 package for transit and i's p actical use. Owing to the unreasonable 

 prejudice in carrying this article on the part of many railways and 

 steamship companies it is a most difficult article to obtain in the tropics, 

 and the small quantities offered by the retailers in Jamaica are sold at 

 .so high a price— as much as 3/6 per lb —that this valuable insecticide 

 is out of I he reach of the general public for use on any practical scale. 



It seemed desirable, therefore, that the Government should facilitate 

 the supply and distribution of carbon bisulphide for use as an insecti- 

 cide, and through the action of the Chairman of the Board of Agriculture 

 arrangements have been made for the importation and distribution of a 

 trial consignment of this article under conditions most favourable to its 

 use by the public 



It was considered that carbon bisulphide required careful regiila- 

 tion and control under tropical conditions and that its importation, 

 storage and distribution at cost piice could be undertaken by the 

 Island Chemist without unfairness to retailers or departing from the 

 general policy of the Grovernment. 



A preliminary consignment has been received from England at a 

 very favourable rate and of exceptional quality. This will pay the 

 usual ad valorem duty and .an b -■ supplied to the public in special 

 drums holding lOOlbs, lOlbs. or 51bs. each at actual cost price* Packed 

 in a special manner, this bisulphide will be carried by freight trains 

 on the Government Euilway at the Chemist's risk. Arrangements 

 have also been approved for storage and distribution from Govern- 

 ment Petroleum Stores at different cntres in the island. A supply of 

 carbon bisulphide should, therefo-e, be obtainable in any part of Ja- 

 maica at the lowest possible cost and with tlie minimum of risk con- 

 sistent with its safe storage and transit. 



All applications and enquiries should be sent to the Island Chemist, 

 Government Laboratory, Kingston. 



* Price 4d. per lb. 



