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THE TROPICAL AGRICULTURIST. [SEPXSMBEk i, 1885. 



make default, so as to call for a direct restitution. 

 AVith respect to irou, sulphur, chlorine, soda, silica, aud 

 carbou, the soil is sufficiently supplied with tlie first 

 five, aud the air abundautly rich with carbonic acid for 

 the second, as never to call for special applications. 



Except in the case of soils where lime has to be 

 added for other than plant food ends, the former has 

 only to occupy himself with potash, nitrogen, and phosp- 

 horic acid. Now the average yield of an acre of wheat 

 in France is about 10 bushels, that which means, straw 

 included, an annual removal from the soil of 39 lb. of 

 azote, 27 lb. of potash, and 13 lb. of phosphoric acid. 

 Only a part of this quantity or the moiety at most is 

 returned to the soil under the form of manure. If then 

 laud be not unexceptionally rich, its fertility must 

 diminish. There are grain regions in America and Italy, 

 where such has occurred to the extent of 50 per cent. 

 To augment the fertility of the soil, more nitrogen, 

 potash, and phosphoric acid must be added, than what 

 the grain, milk, meat, &o., produced, carry away, and that 

 the ordinary supply of farm yard manure at best, only 

 represents a part of what has been so carried off. 



It was only in 1810 that Liebig and his disciples ex- 

 plained the true theory of exhaustion of soils. Till then, 

 it was supposed fertility depended on organic matters. 

 By the analysis of soils aud the ashes of plants,^ Liebeg 

 showed that nitrogen, potash and phosphoric aciil were 

 the essential ingredients of fertility, and that the soil 

 itself and the atmosphere sufficed for the rest. But 

 other equally important discoveries remained to be made 

 to complete Liebig's work : that of the absorbent power 

 of the soil for fertilizing substances, as demonstrated by 

 Huxtable, Thompson, and AVay, and what is known as 

 the dialytic phenomena, revealed by Graham. It was 

 presumed that the plant took up by its roots the pot- 

 ash, [ihosphoric acid and nitrogen, that is to say, am- 

 monia, iu a solution of water, and that these matters 

 filteretl out of the soil. Now Way has demonstrated, 

 by direct experiment, that such is not the case; they 

 are held prisoners by the absorbent power of the earth. 

 It is not the same with lime, soda and nitric acid which 

 pass tbro\igh the soil, as if in a filter. This explains, 

 why in water from field drains, springs, and all land 

 waters, these substances are present, while a trace of potash, 

 ammonia, and phosphoric acid can hardly be there detected. 



Schloesing has confirmed, that this potash, &c., cannot 

 exist in the soil in a state of solution. On examining 

 the liquid of fertile laud, he found these nutritive min- 

 erals to be absolutely insufficient to account for the 

 developement of the plant. How then iloes the plaut 

 obtain its food? 



Graham, Sachs, and Foeller have proved by repeated 

 experiments, that animal or vegetable membrane has 

 the power, when surroumk-d by a liquid on one side to 

 dissolve, without filtrating a solid substance placed on 

 the other side, but capable of being dissolved in that 

 li()uid. Now the li(iuid in the interior of plants is acid, 

 and bv virtue of that acidity capable of dissolving min- 

 eral phosphates in contact with the external tissue— the 

 membrane, of the roots, and without the aid of any 

 bathing solution form the soil itself. Hence the practical 

 deduction, the fecundity of a soil depends, first, on the 

 state of dissemination of the fertilizers therein, and 

 next, on their contact vnth the rootlets; the more nu- 

 merous this contact the better the plant will be nour- 

 ished and the more superior the yield. 



The farmer cannot count then on the rain to dissolve 

 the potash, phosphoric acid, &c., he must rely on his 

 own skill to distribute such minutely in the soil, to 

 allow it to absorb them, and so reach the roots every- 

 where. The nitrates, those precious sources of nitrogen, 

 are not absorbed by the soil, as they filter through it. 

 Hence, apply the potash, phosphate aud ammonia 

 manures, when tilling, aud cover in, as deep as the 

 roots of the crop to be cultivated generally penetrate; 

 but in the case of nitrates, apply them only when 

 covering in sowings. For getting this distinctmn, may 

 explain the failure of many chemical manures. IM. Peter- 

 man has experimented with manures, on the same soil, 

 at variable depths, with beet, he obtained returns differ- 

 ing by S.'? to 41 per cent iu favor of manure ploughed 

 down 6 and 12 inches, as compared with that harrowed in. 



INDIA. RUBBER IN MOZ.\MBIQUE. 



The collection of Indiarubber in Mozambique is of very 

 recent date ; but it has so rapidly extended that it 

 now forms the largest and the most valuable export of 

 the Colony. Not less than £50,000 worth of Indiarubber 

 passed through the Custom-house during 1883 ; whereas 

 in 1873, the export was only of the value of £443. 



The rapid extension of the rubber industry is due 

 entirely to the natives, and in its working they have 

 been left from the very commencement to follow their 

 own devices. An enormous number of valuable trees have 

 been destroyed by them. They also bring into the market 

 an inferior quality of rubber extracted from the roots of 

 the trees. When the natives see that no more juice 

 can be drawn from the stem, aud believe the tree to 

 be dead, it is their custom to pull up the root<!, and 

 by pounding and boiling to extract the last trace of 

 rubber from them. It appears that the Indiarubber 

 exported from the northern portion of the province, is 

 drawn from only one species of plant of the genus, 

 Landolphia whereas there is reason to believe that two, it 

 not three, species exist in the same locality. Two new 

 species of this plant, called by the natives Mbuugu aud 

 Mtoha, were sent to the Royal gardens at Kew in 1878. 

 One of these, the Mbungu, is to be found upon the 

 mainland of Mozambique. Consul O'Neil has met with 

 his species upon several parts of the coast, but now here 

 do the natives appear to be aware of its value. Grow- 

 ing upon more humid soil thau the species from 

 which the rubber of Mozambique is extracted, it yieUI.s 

 a more watery juice, which the native has not yet dis- 

 covered a method of congealing. Ou being asked if they 

 never attempted to collect it, they have replied : " It is 

 impossible, it is too watery, we can only use it for 

 making bird traps." Smeared over and about the traps, 

 it adheres to the feathers of the birds, and retarding 

 their flight, makes them easy captives. There is also 

 another species upon the coast land of Mozambique, 

 called by the natives " Kava," utilized for the extraction 

 of rubber, and bearing a like watery juice. The milk of 

 both these may be congealed by the application of the 

 juice of the lime, as is done in the collection of a similar 

 species of rubber in Madagascar. The market value of 

 the rubber drawn from these plants yielding a very watery 

 juice would probably always be less than that which is 

 wound off by hand; for in congealing it carries with it 

 a certain amount of water, it loses weight for months 

 after collection. " But," says the Consul, "this collection 

 is easier, aud in the untouched forests that exist of these 

 distinct species of the rubber plant, I think I may vent- 

 ure to say, there lies an additional source of wealth to 

 tlio province." — Indiantl<her and Giittnpercha Journal. 



THE AMERICAN RUBBER "CORNER" 01' ISS2. 

 The annual product of crude rubber amounts to many 

 millions of dollars, and in its manufacture iu America 

 alone from 30,000,000 dols. to 40,000,(100 dels, are investe<l. 

 Yet within three months, by shrewd and audacious and 

 skilful manipulations, a single individual '' cornered" this 

 commodity, forced up the price from 95 cents to 1 dol. 

 20 cents per poand, and kept it at the latter point for 

 several months, notwithstanding that the nominal price 

 of crude rubber is from CO cents to Co cents a pound. 

 The man who diil all this was one J. C. Gon<;alves ^■ianna, 

 barao de Gondoriz. He bad before shown his ability as 

 a remarkably bold and successful speculator. Once a 

 promising clerk in the rubber exporting house of Victor 

 Itodrigues d'Oliveira, of ParA, Brazil, he was in 1877 

 admitted to partnership, and soon became controlling spirit 

 of the firm. His first great achievement was executed 

 iu 1879, when by skilful scheming he forced the price of 

 rubber from 40 cents to 1 dol. per pouml, and made for 

 himself a fortune of several hundred thousand dollars. 

 In 1881, he attempted a similar experiment, but this time 

 met with less success. Treacherous contracts made by 

 his junior partner with New York merchants involved him 

 in great diflicnlties, and long negotiations, after he saw 

 that he must fall, resulted in his ])aying 52,000 ilols. 

 in cash to two of the manufacturers whom he had 

 treated most shabbily. FaiUng in this attempt, he next, 



