Vol. XV. No. 380. 



THE AGRICULTURAL NEWS. 



379 



is the staple crop grown by the Europeans, but rice and 

 various varieties of millet are produced in great quantities 

 bj- native cultivators. Ground nuts and sun flower seeds 

 are beginning to be produced on an increasing scale for 

 the manufacture of oil. Tobacco grows everywhere, but 

 its success from a commercial stand-point entirely depends 

 on cost of production. Its prospects in Mashonaland, 

 and in the vicinity of Fort Jameson are encouraging. It is 

 probable also that in a few years' time Southern llhodesia 

 will export citrus fruits on a large scale to Europe. Apple.s 

 have been tried with varying success, and may in time 

 succeed in the vicinity of Inyanaa. 



Owing to the distance which intervenes between Rhodesia 

 and the markets of the Union, Rhodesia has already been 

 compelled to face the problem of e.xport and to promote 

 co-operation between procucers with ihis objeot. A large 

 tonnage of maize has already been exported. Considerable 

 quantities of tobacco have been sold on the London market, 

 and experimental shipments of oranges have been mide 

 succe.sslully. The export of meat and other cattle products is 

 receiving attention, and one looks forward wibh confidence to 

 the day when Rhodesian chilled meat will be exported to this 

 country via one of the West Coast port.=. But before this 

 (!an occur large herds must be built up and the standard of 

 local cattle improved. This will take time, but meanwhile 

 there is every reason to expect that a considerable export of 

 canned meat will take place, and possibly also of dairy 

 products. 



So far reference has been made only to the possibilities 

 in more elevated regions. In the futura when the Salisbury 

 Railway reaches the Zambesi, there is little doubt that a 

 number of valuable products of a more tropical charactei-. 

 such as cotton, sugar, sisal and other fibres, rubber, and oil 

 seeds, will be raised by p'anters in the lowlying regions 

 which abut on the Zambesi and T.,aungwa Rivers and their 

 tributaries. 



As regards wild rubber, a number of rubber producing 

 plants of the genus Landolphia are met with over considerable 

 areas in Northern Rhodesia. They include sever.al species 

 of rubber vines and of bushes which produce root rubber 

 The quality of rubber produced is excellent, and the 

 payability of the industry depends entirely on the density of 

 distribution of plants and the cost of transport. The British 

 South Africa Company has established a steam factory, at 

 Chambesi, which started work just before the war broke out 

 but which, owing to the shortage of labour brought about by 

 the military operations on the Northern Border, has been 

 temporarily clcsed down. It had, however, been at work 

 sufficiently long to enable samples of the product to be sent 

 home and to supply data in regard to costs of production. 

 As the result of this preliminary information, it may be 

 stated that the production of rubber is likely to become one 

 of the staple industries of Northern Rhodesia. 



Experimental Work in Bombay.— We have 

 been furnished with two annual reports on experimental work 

 at agricultural stations in Bombay. In regard to that dealing 

 with the Nadiad Agricultural Station, reference may be 

 called to the experimental work with cotton in which consid- 

 erable attention has been given to Cambodia Concerning 

 oil seeds the yield per acre of a number of varieties of castor 

 seeds is given together with the percentage of oil. The 

 results of selecting castor seed are also given. The second 

 publication describing work at the Surat Station deals with 

 experiments with cotton, oil seeds (ground nuts), and certain 

 manurial experiments. 



CONCENTRATING LIME JUICE 

 BY FREEZING. 



An interesting piece of investigation, which may lead to 

 results of practical importance, has been carried out by the 

 Agricultural Department, in Dominica. During 1915-16, 

 the Commissioner of Agriculture for the West Indies brought 

 to the notice of the Dominica Department an interesting 

 article on the concentration of cider by freezing, which 

 appeared in the Year-liook of the United States Department 

 of Agriculture for 1914 In this experiment it was shown 

 that it was possible to concentrate cider by this process to 

 one-fifth of its bulk without altering its properties as 

 a beverage. 



It was suggested that experiments be conducted to 

 determine the behaviour of raw lime juice when treated in 

 a similar manner. It is obvious that if raw lime juice, which 

 is shipped for cordial purposes, could be concentrated without 

 changing its essential properties, there would be a very 

 considerable saving in freight, packages, and other charges. 



The phenomenon that solids in solution can be concen- 

 trated by freezing the liquid and removing a portion of the 

 ice formed has been known for a long time, and in the 

 reverse way this has often been made use of in obtaining 

 drinkable water from sea-water. In this case it is the frozen 

 portion which is saved, the amount of sodium chloride which 

 it contains being so smill as to make it moderately drinkable. 



Numerous experiments were conducted during 191.5-16 

 to ascertain how lime juice behaves on freezing, and the 

 results obtained are discussed in the Report of the Agri- 

 cultural Department, Dominica, for 1915-16 



The raw lime juice throughout the experiments was 

 placed in a receptacle of block tin or a glass jar, which was 

 packed round with a freezing mixture of salt and ice, which 

 reaches a temperature of between - 5° and - 10° C. In a short 

 time the juice becomes cooled to a temperature of between 

 - 1° and - 2° C. Shortly after it will be found that ice has 

 separated on the side of the jar, and on continuiug the process 

 this layer gradually thickens until later a core of juice 

 remains and finally a solid mass is formed. 



The sides of the receptable are now warmed, and the 

 solid mass slips out on to a basin where it is cut up with a knife 

 into pieces of suitable size to enable their being readily 

 placed inside the basket of the centrifugal machine. 



The centrifugal is whirled round for a few minutes, and 

 throughout these experiments the whole was melted in stages 

 of known volumes. 



The capacity of the centrifugal machine was such that 

 only 500c. c. of juice could be "conveniently handled 



The general conclusions arrived at are given in the 

 Report, and are as follows: — 



1. Raw lime juice when frozen and treated in the 

 centrifugal can be concentrated without affecting its properties 

 as a beverage. 



2. If the juice is treated once only, the acid content may 

 be increased from about 13 oz. per gallon to over 20 oz. 

 {ler ga'lon. 



3. If this be refrozen a juice containing 30 oz. per gallon 

 can be obtained. 



4. The low testing juices can be converted into citrate 

 of lime, thus eliminating all losses excepting those of handling. 



5. This process enables a very considerable saving to 

 be made in freight, charges, and packages, amounting to 

 between 40 and 60 per cent., the actual amount depending on 

 whether the juice is frozen once or twice. 



