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THE TROPICAL AGRICULTURIST. 



[June 2, 1884. 



THE OEIGIN OF GRAVELLY SOILS. 



[the GABDENEfi'S AND FAEMEr's KEASON ■n'HT.] 



Gravel is a description of sand, but consisting of larger 

 particles of disintegrated rocks, distributed over the face 

 of the earth, chiefly by the action of water. Gravel, having 

 been dispersed by a more powerful agency than that which 

 caused the distribution of sand, differs more widely in its 

 qualities, because of its frequent admixture with various 

 substances, organic remains in a fossil state, and especially 

 clay, loam, flints, iron-stones, &c. Hence there are rich 

 gravels, poor gravels, himgry gravels, sharp gravels. Sands 

 will frequently be found to be the production of flat count- 

 ries, gravels of the mountainous and rocky. The character- 

 istic of gravelly soils is the quantity of loose stones which 

 they contain. These stones will be found to consist of those 

 varieties of rocks which the mountains of the country afford ; 

 and the nature of those rocks will frequently indicate the 

 characters of the soil ; thus, soils of which the stony matter 

 is silicious are generally found to be barren, while those of 

 which it is calcareous are found to be fertile. 



How may gravelly soils be improved? By draining, if 

 they are troubled with springs, which is frequently the case ; 

 by ploughing rather deep ; by mixing them with large quant- 

 ities of clay, chalk, marl, peat, or other earth; by frequent 

 returns of grass crops; by repeated applications of manure; 

 and by irrigation, more especially if the water be fuU of 

 sediment and judiciously applied. The materials to be added 

 to gravelly soils of a calcareous nature, to increaae their 

 fertility, are clay and clay loam. A mixture of carbonate of 

 lime or chalk with clay has also appeared beneficial to such 

 soils. Chalk is particularly recommended for those kinds of 

 gravelly soil which contiguity to springs is apt to render 

 moist in the winter season. The application of chalk is 

 stated as having a powerful effect, not only iu counteracting 

 the redundant moisture, but in correcting the tendency to 

 become parched in the summer — an evil to wliich most 

 gravels are in some degree liable, and which is often so 

 injurious to the crop. The defect of vegetable and animal 

 matters is to be supplied by means of dmig from the farm, 

 in its reduced state ; and much benefit is derived from other 

 animal matters, prepared in the form of composts, with 

 good loamy mould, ashes, clay depositions of rivers and ponds, 

 with other substances of a similar nature. The proper 

 alternation of green vegetable and other crops also contributes 

 greatly to improve the fertihty of such lands. 



What is the origin of clayey soils? Clay is a mixed 

 natural earth, very widely distributed. It consists of a large 

 proportion of alumina, imlted to sihca, of various degrees of 

 fineness, and frequently also a portion of carbonate of lime. 

 The formation of clay deposits took place, according to 

 geological theory, in consequence of the degradation and 

 waste of certain portions of the globe, followed by a re- 

 moval of the materials to localities of comparative tran- 

 quility. In the formation of claj'ey deposits both chemical 

 and mechanical agencies were exerted. The mechanical 

 agency operated in the disintegration of solid parts and the 

 removal of the fragments, and the chemical agency operated 

 in the uniting of alumina, silica, &c., into a compact earth. 

 A clay soil is distinguished above every other for its 

 tenacity. It is principally composed of particles of matter, 

 many of them so small that when separated from each 

 other they are imperceptible to the touch, and will easily 

 float in water ; yet. these minute particles form a soil that 

 is far more tenacious than any other species of earth. 

 Clay always contains iron, iu a higher or lower degree of 

 oxidation ; and it is probable that this metal constitutes 

 an essential part of it. 



How may clayey soils be improved? By a suitable 

 admixture of other soils to amehorate its textm-e, such as 

 common sand, sea sand, and above all limestone gravel. 

 Peat moss, which has for some time been dug up and ex- 

 posed to the action of the atmosphere, may be used with 

 advantage. It is likewise nece.ssai-y, in the course of its 

 cultivation, to enrich it with putrid and calcareous manures; 

 and it may be much improved by having a considerable 

 quantity of ashes mixed with its putrescent manures. 

 Burning part of the clay, to be afterwards incorporated 

 ^vith the soil, to render it more friable, has likewise been 

 attended, iu some instances, with advantage, more especially 

 if there is any marl in its compcsition.— Zcfff/o'. 



BOUKNVILLE, THE "OOOOA" TOWN. 



(Oadbuky's Manufactobt, Bibmingham.) 



After describing the little colony of six hundred workers 

 completely housed and kindly looked by the Messrs. Cadbury, 

 and describing the Cocoa Plant and Pod, the roving corre- 

 spondent whom we quote describes graphically the processes 

 of preparation as follows : — 



AVhen the fruit is quite ripe it is gathered, generally, by 

 being shced from the boughs by a cutlass wielded by the 

 arm of some stalwart negro; the pod being sUt open and 

 the nuts, with then- creamy adjunct which holds them al- 

 together, placed iu casks, where they are pressed down by 

 weights and left to ferment, so as to get rid of the pulp, 

 and, as it is said, improve the flavour of the cocoa. After 

 some httle time has elapsed the nuts are then placed in wide 

 open trays in the Boucan or drying-house, where they are 

 exposed for some days to the sun, after which they are 

 placed in bags and exported to England. 



The first process the cocoa undergoes is to cleanse it from 

 all impurities of dust, dirt, and such-like that accompanied 

 it from the land of its birth. This is done by sifting it in a 

 long cylinder fitted with variously gi-aduated sieves. From 

 these the nuts drop, automatically assorted to several sizes, 

 into boxes below, cleansed from all superfluous substances, 

 and ready for " cookmg " — then- second experience being 

 to be roasted in revolving cylinders over bright coke fires. 

 It is requisite for those who have charge of the cuisine to 

 determine the precise period at which the nuts are sufficient- 

 ly roasted, for very much depends upon this point. A 

 miscalculation of time, of course, would tend to spoil the 

 flavour of the nibs, not to speak of burning them and so 

 rum them altogether. In connection with this process, 

 methods of treatment peculiar to the estabhshment are 

 successively adopted. After being roasted, the nuts are 

 placed in trays to cool, the fresh air speedily reduces the 

 temperature of the cocoa beans, and they are then ready 

 to be what is technically termed "broken down." The 

 now crisp, roasted nuts are placed in a hopper, and after- 

 wards raised by an elevator, and passed through a machine 

 which gentle cracks them, disengagmg the hard thin skin, 

 which by this means can be separated from the nutritive 

 portion of the nut — that is, the rich glossy kernel, known 

 in the market as " cocoa nibs." The separation is effected 

 by a winnowing machine. From the outlet of the cracking 

 machine the husk and nut are carried to a point over the 

 " winnower," and as the cracked nut falls into its allotted 

 receptacle below, a powerfvd blast of cold air blows away 

 the sheUy parts into an upper division of the same receptacle. 

 They are next taken to the grinding room, where a series 

 of revolving mill-stones speedUy resolve them into a thick 

 brown fluid. From this liquid paste the oil is extracted, of 

 which there is some 50 per cent in the nuts; and then the . 

 substance, without the admixture of a single foreign element, 

 but pure as it came originally from the tree, with the excep- 

 tion of being deprived of its fat, having " done Banting," 

 so to speak, is known as "Cadbury "s Cocoa Essence," cele- 

 brated for its purity and nomishing properties all the world 

 over, an essence which indeed has gained the Uttle town 

 on the banks of the Bourn its local habitation and name. 

 The cocoa essence baring been reduced to a very fine 

 powder is then weighed and packed automatically iu the 

 well-known packages familiar to aU cocoa consumers by an 

 ingenious American machine which contrives to measure and 

 put up some twenty thou.sand parcels of this theobromine 



or '• food of the gods," as Linnajus christened it — per diem. 



The next article of Messrs. Cadbury 's manufacture, and 

 one almost as important as that of their cocoa essence, is 

 the Mexican and other sweet chocolate for lionbon'iicij-cssiii(l 

 other dainty uses too numerous to be specified. The pure 

 cocoa is in the first place incorporated with the best white 

 sugar in a machine called a miiunytur or mixer, where heavy 

 granite rollers like millstones set on end, and a double-bladed 

 knife acting as a screw propeller, thoroughly incorporate 

 the substances into each other, after which it is flavoured 

 with vanilla. The "Chocolate," as the material is now 

 called, is then run into moulds, and cooled on stone slabs 

 iu a cellar, the temperature of which approaches more to 

 the freezing point than any other part of the establishment 

 I risited. 



After seeing chocolate thus " put through its faces," in 

 slang phrase, I wss u.shered into the cream moulding room 



