.Vol. XVI. No. 40S. 



THE AGRICDLTURAL NEWS. 



395 



"SoutheiTi States or from Egypt, and we would add, or 

 from Brazil also, in ord^ to prevent the introduction 

 of the boll weevil or the pink boll worm. 



Fixation of the Nitrogen of the Air. 



An article in Nature, August 30, 1917, on the 

 progress of applied chemistry, draws attention to the 

 fact that perhaps no development of chemistry promises 

 greater consequences to mankind than the fixation of 

 the nitrogen of the air. The rival methods at the 

 present time are the direct method of oxidation of the 

 nitrogen to nitric acid, and the production of ammonia 

 by the combination of nitrogen and hydrogen. Various 

 means of bringing about the first result are employed, 

 and it is contended that the Kilburn Scott furnace 

 increases the efticiency of the process by bringing the 

 whole of the included air under the action of the 

 ■electric spark. With respect to the second result, the 

 synthesis of ammonia, the latest refinements of chem- 

 istry and physics are of enormous importance in the 

 very complicated process. The actual combination of 

 the nitrogen and the hydrogen is brought about by 

 catalysts consisting of various metals or combination 

 of metals. The activities of the chemist in producing 

 cheap fixed nitrogen will have a profound inliuence on 

 the mannrial problems of agriculture. 



Progressive Desiccation in South Africa. 



In reviewing a paper on this subject, the reviewer 

 in the Geographical Journal, October 1917, is not 



■ quite convinced that there is positive evidence of any 

 diminution of rainfall in .South Africa during the last 

 two or three hundred years. Whether or not this 

 is the case, it is asserted that the progressive 

 desiccation of the country is evident. Possibly this 

 has been effected through a change in the character of 



. the rainfall from soft soaking rain to violent thunder- 

 storms and cloud bursts, which may be traceable, in the 

 first place, to the extenisive felling of forests and burn- 

 ing of grass land. Such clearings facilitate the rapid 

 run off of water which would otherwise percolate slowly 

 into the soil. This rapid run ofi' of water brings about 

 desiccation and consequent heating of the soil. Such 

 tracts of bare heated land are unfavourable to a well 

 distributed rainfall, the influence being explained as 

 follows: 'If a current of air laden with moisture meets 

 a land surface, the question whether or not the 

 moisture shall be precipitated depends on the tempera- 

 ture of the land surface. If this is cooler than the 

 vapour-laden air, it causes the density of the air to 

 increase, the air becomes .saturated, and precipitation 

 takes place. If on the other hand, the temperature of 

 the ground is higher than that of the air, it causes the 

 air to expand, rise, and carry off the moisture it brought.' 

 It is quite likely that some such effect as this 

 does take place, and that, ceteris paribus, forest- 

 covered country tends to provoke a more uniform 

 condensation than bare country; but the question of 

 the relation between forests and rainfall, although 

 discussed over and over again, cannot, lie •^aid to be 

 definitelj' settled yet. 



Food Conservation. 



The suitability of vegetable oils — coco-nut, cotton 

 and ground nut — for human consumption as substitutfes 

 for butter and lard has often been pointed out. With 

 reference to the present shortage of the butter supply 

 in Great Britain which is reacting on the milk supply, 

 so that a shortage ' of the latter is to be feared— 

 a veritable disaster to infants and invalids — Mr. 

 Hamel Smith, the editor of Tropical Life, suggests 

 a ^remedy. In a letter on this subject dated October, 

 1.5, 1917, which was published in the Financier, 

 Mr. Smith suggests that it is advisable (\) to prohibit 

 the manufacture of butter from cow's milk for the 

 present in Great Britain, and (2) to encourage, perhaps 

 to insist on, the extraction of all vegetable oils, when 

 practicable, at the centres of production, thereby redu- 

 cing the space needed for shipment of the copra and 

 oil seeds in bulk to Europe. This would have the 

 excellent result of leaving behind on the estates where 

 such crops are produced the coco-nut or oil-cake as 

 a valuable food for cattle, pigs, and poultry. Such 

 a course ought in turn to enable many more cattle and 

 pigs to be raised profitably in tropical countries, and 

 to allow of the carcases being exported at a cost 

 low enough perhaps to be .able to compete in British 

 markets with those from .South America. Mr. .Smith 

 believes that in times to come the tropical, rather 

 than the temperate zone, will produce the greatest 

 number of pigs, if only on account of the 'mountains' 

 of poonac, that is to say, the meal left after extracting 

 the oil from the copra, which it does not pay to ship 

 elsewhere for feeding animals on. 



Fresh Fruits and "Vegetables as Substitutes for 

 Meat and Bread- 



Farmer's Bulletin S'/l, of the United .States 

 Department of Agriculture, contains many recipes 

 whereby fresh fruits and vegetables may profitably be 

 employed to take the place of other staple foods. It 

 points out that the principal food substances needed in 

 human diet are starch, sugar, vegetable acids and fibre, 

 fat, protein, mineral substances (such as iron, calcium, 

 phosphorus and others), and also certain substances 

 necessaiy for growth and health, which have only re- 

 cently been discovered, and to which the names vita- 

 mines and hormones have been applied. 



The bulletin points out that peas, beans, and 

 similar legumes are most useful in reducing the quan- 

 tity of meat required in a well balanced ration: that 

 sweet potatoes and similar vegetables are wholesome 

 substitutes for bread, while all fruits and greens, and 

 succulent vegetables supply the diet with mineral 

 substances and the vitamines essential to health which 

 are present in them. If used intelligently, such a diet 

 consisting chiefly of vegetables, will not lack starch or 

 protein. In connexion with these foods, however, it is 

 highlv desirable to, use skim milk, which like fresh 

 fruits and vegetables, is perishable and can only be 

 profitablv u?ed within a short period after its prryjijc- 

 tion. 



