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A populatiou of 38 icillions, such as that of Fracce, 

 borrows then from its alimentation some 80,000 tons 

 of phosphoric acid per annum. If the death-rate of 

 this population be reckoned at 23 per 1,000 inhabitants, 

 the amount of phosphoric acid in their remains 

 represents a proportionate total of the acid, definitely 

 abstracted from arable laud. 



Per contra, the annual dejectiansof acity's inhabitants 

 constitutes a partial restoration of the acid to the soil 

 some forty per cent of it is however totally lost for 

 agricultural wants. The extraction of the fertilising 

 elements from the soil — chiefly phosphoric acid — without 

 any being restored thereto, was one of the main 

 causes of the decay of the empires of Greece and 

 Rome ; of the power of the Arabs and of the prosperity 

 of Spain. When the sources of their food-supply 

 ■were exhausted by a vampire system of cultivation 

 their power and prosperity followed suit. 



Moderns are more fortunate than their ancestors 

 in being able to secure to-day inexhaustible supplies 

 of phosphoric acid. French agriculturists are indebted 

 to the late M. de Molou, for his discovery of natural 

 beds of phosphate of lime. Messrs. Thomas and 

 Gilchrist have utilized the slag, cinders or scoriae, this 

 once useless out-put of metallurgic industry, but now 

 invaluable for its richness in phosphoric acid resulting 

 from the dephosphorization of iron. The employment 

 of phosphorus has become to-day the pahuliom vita 

 of crops. Continental farmers rush after the fertilizer 

 almost like diggers to a gold mine. 



There are 'hree natural groups or sources of 

 phosphates ; nodules, incorrectly called coprolites 

 peculiar to stratified rocks, and containing 34 to 60 

 per cent of phosphate. When ground down to a fine 

 powder it is easily absorbed by plants. Its action 

 is almost equal to that of pho.sphoric acid when 

 rendered soluble in water. The second group is 

 called apatite. It is one of the constituent elements 

 of an eruptive rock, in the middle of which it is dissemi- 

 nated more or less frequently, but ever variable. It is 

 almost pure phosphate — as high as 95 per cent crystalliz- 

 ed, very hard, and imbediled in a vein enclosing potash. 

 The third source is included under the generic name 

 of phosphorite. In structure, it partakes of the shape- 

 less coprolit? and the crystllized apatite. The latter 

 and phosphorite even when reduced to an impalpable 

 powder are less assimilable than the pulverized nodules. 

 Their principal employment is for the production of 

 superphosphates due to their richness in phosphoric 

 aciii and carbonate of lime. However, they are the 

 nodules from the South of France, Nassau, and Spain, 

 which furnish agriculture with four-fifths of its 

 commercial phosphates. 



As already stated, the nodules when in a .'tate of 

 powder, are rapidly taken up by plants. The apatite 

 and phosphorite present a greater resistance to the 

 action of the internal juices of the plant, which take 

 up— by the process of diffusion — through the external 

 envelope of the root, the phosphoric acid of the soil. 

 Obviously, the practical consequences flowing from 

 these remarks is, to reduce the fertilizers to a state 

 of extreme division, before applying them to the 

 soil. And let the dose be liberal, say 2| cwt. per 

 acre, which will tell on four or five consecutive crops. 



The apatite and phosphorite can be quickened iu 

 their action if when reduced to powder they are 

 made into a compost and watered with urine. But 

 as the nodules and slag powders answer so well, and 

 are so cheap, there is no necessity for recurring to 

 the others. In the case of organic superphosphates, 

 the only superiority they can claim over the powders 

 la that of being more immediately soluble. But 

 against ;his advantage must be placed the greater 

 expense. M. Wagner of Darmstadt has clearly proved 

 by his experiments the necessity of employing the pow- 

 dered cinders in a state of great fineness. At Quareux 

 in Belgium, the employment of nitrate of soda with 

 the pulveriz 'd slag has given important results in 

 the culture of oats. The cinders reduced to powder 

 cost fr, 45 per ton, and represented about '23 per 

 cent of phosphoric acid. 



The agricultural problem consists to produce much 



*t A littls outlay • but reojuaerative crops caosot ho 



produced without abundant manurings, no djoto than 

 could a good dinner be prepared from nothing. Here- 

 tofore, soluble phosphates cost half a franc per lb ; 

 now the insoluble acid iu the form of powder costs 

 fifty per cent less. The slag gave wonderful results 

 when applied to grass land. Near Freising in Bavaria, 

 a dose of 8 cwt. of the cinders per acre and cost- 

 ing only 9 fr. doubled the yield of hay. dissociated 

 with nitrate of soda equally gratifying results were 

 produced. 



The movement of opinion for the extension of experi- 

 mental farms is rapidly extending. The Goverrment 

 accords sometimes material aid for the execution of 

 the experiments, but more usually lends its agri- 

 cultural representatives to superintend their carrying out 

 and to report the results. Ordinarily, a spirited pro- 

 prietor places some acres, and all corresponding 

 facilities at the disposal of the oflBcials. These experi- 

 mental acres are ostensibly devoted to the solution 

 of local or rather regional questicnSj such as the 

 most suitable seeds, time and manner of sowings, 

 manures, and the influence of climate i:c. thereon. 

 Each experiment is tested pending four years and 

 controlled by an impartial official. It is on these lines 

 that M. Hardou has placed five acres of his farm near 

 Melun to test wheat-experiments ; at first, the farmers 

 kept aloof, but now they watch the proceedings with 

 something like the interest of a horse race. Nothing 

 is concealed ; all accounts and projjress are open for 

 any person to consult, and a register is kept for 

 visitors to make suggestions or record their impres- 

 sions. In a few years when the reports on these 

 disinterested experimental lauds are co-ordinated, they 

 must give rise to a consensus of practical conclusions, 

 equivalent to a positive code for agriculture in general 

 and for the localities in particular. 



Science has long ago established the indispensableuess 

 of nitrogen in the production of plants, and that 

 agriculture appreciates practically by the importance 

 of that element in the manures furnished to the soil. 

 But what is still uncertain is to know, if the atmosphere, 

 which is an inexhaustible store house of azote, and 

 offers it gratuitously to plants, is the source of 

 nitrogen for the vegetable world. The whole subject 

 has just been discussed at the Congress of Scientists 

 held at Berlin, so we have all that is known up to 

 date on the question of the absorption of free nitrogen 

 from the air. 



We know that an electric spark couverts the azoto 

 of the atmosphere into nitrate of ammonia, and which 

 the rain brings down with it to the soil ; but it is 

 calculated that during a year an acre of ground docs 

 not receive more than 9 lb. in this form. Practice, 

 however, has not the less aflirmeil, that certain 

 plants, clovers especially, had the exceptional power 

 to utilize free nitrogen for the formrttion of their 

 tissues, while at the same time euriching the soil. 

 The I'esults of SchuUz's experiments at Lupitz seem 

 to roughly confirm this opinion. On the other band 

 the researches of Boussmgault are decisive respecting 

 the non-absorption of free nitrogen from the air. 



Boussingault raised leguminous plants on a soil 

 deprived of nitrogen, and so they had no other sourcu of 

 deriving it save from the air. On analysing the plants, 

 he only found in their tissue a quantity of azote 

 equal to that existing in the seed, and so only obtainable 

 during the process of germination. This was precise 

 negative evidence. 



Now the importance of these issues is plain ; if a 

 farmer pursues a system of culture couutiug on tbo 

 air to supply the nitrogen, ho may come to grief, 

 Dietzell unlike Bou.ssingault, operated on the arable 

 soil itself, and arrived at the same results as that 

 distinguished chemist. .Joulieand Berthelot in France, 

 and Frank in Berlin, obtained results opposed to 

 Dietzell. Doctors differ. Joulie asserted that rye; 

 clover and rye grass absorbed free nitrogen from the 

 air. Berthelot only occnpied with the soil itself, 

 stated, that after a lengthened lapse of time a sterile 

 soil, if possessed of a certain warmth, beca-ate rich 

 in nitrogenous compounds, Frank, with a remarkable 

 exactness on the same soil, cropped and uncropped 

 fOHQfl that nitrogen had been absorbed, but iJOW Qf 



