April i, 1886.] THE TROPICAL AGRICULTURIST. 



695 



DECOETICATED COTTON-SEED CAKE. 

 Sir, — M}' attention has been directed to the letter 

 on the above, published hi the Field of the 12th inst., 

 and I can cordially agree with the writer in his sug- 

 gBBtion that buyers should pay more regard to the 

 actual composition of ditferent lots of the aboveiiamed 

 cake. Having had more than twenty years' ex- 

 perience in agricultural analyses, I can testify to ths 

 fact that badly i)rep.'ired decorticated cotton-aeed cake 

 has over and over ngain been the source of serious 

 loss uf cattle and sheep, especially young animalf, 

 who are unable to digest the hard lumps, which being 

 often associated with some cotton wool, render proper 

 separation even imposible, much leiss digestion. 



A great deal of stress has been laid by some 

 chemists upon the reduction of the percentage of 

 oil which has taken place of late years both in lin- 

 seed and cotton cakes ; and in another paper I have 

 already pointed out thai it is not so much the re- 

 duction of oil that is so objectionable, but the hard 

 pressed character of the cake resulting from this 

 extra pressure that is the real cause of so much 

 mischief among stock. 



We must remember that cotton-seed and linseed 

 cakes are merely the residual products resulthig from 

 the extraction of oil, and that the manufacturer will 

 use his judgment as to how far it pays him to 

 employ improved machinery to extract a larger pro- 

 portion of oil than was formerly the custom. 



There will always be a good demand for cotton and 

 linseed cakes, and though no doubt \he price will be 

 reduced, in consequence of the smaller amount of 

 oil thiy may contain, still, I contend that the true 

 remedy is for farmers to employ m:»chines capable of 

 reducing the hard-pressed cake to a tine meal, which can 

 be sprinkled over cut roots and chaff with far greater 

 advantage, in a feeding sen.se, than the present nut- 

 like lumps, which is the condition now too common. 

 By all means let farmers and buyers generally 

 avail themselves of the aid of chemical analysis to 

 distinguish between the different qualities of cake, 

 and let all cakes be sold by analysis, as manures are 

 now solrl ; but if is quite useless" to grumble .ibout 

 the reduction of oil ; for as long as the manufacturer 

 finds it pays him best to e.xtract as much oil as pos- 

 sible, he will continue to do so. 



As for selling meal instead of cake, every practical 

 farmer knows very well that meal, in this' change- 

 able i-liniate, will not keep sweet any length of time, 

 and the best plan is to grind cake as required, from 

 ilay to day.— JoHv Hughes, F.C.S., 79, Mark Lane, 

 E.L'...Tan. 25.— Field. 



THE SCIENTIFIC MANUFACTURE OF TEA. 



To Till; EoiTOIt OF THE " Ho.Mi: .\ND COLONUL M.VIL." 



^-ir,— I have read very carefully Mr. Main's suggestions 

 and ojiinions as to the use of chemically dried air 

 for ilrying and withering tea. and have also consulted 

 scientific authorities and practical men on the subject. 

 The gener.-il conclusioH seems that for drying it is 

 hardly likely to be of much use, because air at 212' 

 (however damp the clima.e may be) is practically 

 drier thau it could be made by ««(/ absorbent. At 

 that Mioderate heat it contains less than 1 percent, 

 of moisture, aud no one seems to believe that 212 

 could by any possibility be injurious to tea, seeing 

 that, in nearly nil the. drying processes now employed, 

 air at from L'nO_ to ulM' lias been used for many years. 

 Still " the possible is imineuse," and, inasiniicli as the 

 system could be so easily put to the test by all who 

 now use our drying cylinders. I will explain more 

 clearly how this preliminary trial can be carried out. 



Inste.-id of lighting a fire in the furnace, (ill it up 

 with lumps of chloride of calcium oranyolher more 

 convenient absorl)ent, and draw the air "through this 

 into tlie fan and drive it through the air-duct into 

 the cylinder precisely as is now done with hot air. 

 If this desiccated air is sufticiently powerful to dry 

 the lei without any addilioicil heiit, so much the 

 better J but if heat also is n nUd, a coil of steam- 

 pipt; ill the air-duct will .supply that want at a cost 



of a few pounds. It will, perhaps, be admitted that 

 the simple and regular movement of the cyliuder is 

 as good a plan as any for enabling air to act evenly 

 and powerfully on the leaf, and hence wouUl give the 

 process a full chance of success. Chloride of calcium 

 per se is a more powerful absorbent than charcoal, 

 pumice, or other porous substances soaked in its 

 solution and redried. As it dissolved it could bo 

 allowed to run iff into a common boiling-pan to be 

 re-evaporated ; the lumps should be fed lu regularly 

 at the upper feed-hole so as to prevent any air getting 

 into the ];an without passing through the absorbent. 

 Such a trial as this would disturb nothing and spoil 

 nothing; would involve no heavy expenditure, and 

 no discarding of a tried resource for an untried one, 

 and no hazardous "Leap in the Dark." If the tea 

 were not dried in once passing through, it could hu 

 sent through again and again, and its quality and 

 market value ascertained. 



Considering that all the air would have thus to 

 pass through a large bulk of the absorbent, that the 

 absorbent itself would bo in its most powerful form, 

 that such air could then be warmed to any desired 

 temperature and kept perfectly pure, that the t»a 

 would be presented to it in the best form for being 

 dreid, and that both tea and ai' could be kept in or 

 let out of fhe cylinder as quickly or as slowly as 

 might be found best, I think it will be admitted 

 that all the conditions for a full, fair, and completely 

 convincing trial would be present. If successful 

 planters would thereupon adopt more readily and 

 widely Mr. Main's patent air-desiccators ; if not, they 

 conld revert to their present processes without trouble 

 or hindrance. 



It is obvious that these same drying cylinders could 

 he used to test the value of desiccated air at rarious 

 temperatures for " withering " also, but for this process 

 they should be rotated very slowly — .say, once in a 

 minute — so that the leaves should only just be lifted 

 up sufficiently to separate one wet leaf from another 

 and give the air free play amongst them. The volume 

 and velocity of the air should be far less thau in 

 drying, aud ths ends of the cyluider closed up to 

 any e.vtent that practice proved to be best, so as to 

 subject the leaf longer to the action of that air. 

 A .series of experiments should be carried out, care- 

 fully raising the temperature one or two degrees at 

 each working — say from 85* the normal heat of the 

 atmosphere, up to 100', 110'"', or any higher degroe 

 that the leaf would bear without deterioration. It may 

 here be useful to record that the practical planters, 

 who were present at my e.xperiments last year, were 

 perfectly satisfied with the withered condition of leaf 

 when subjected to the action of ordinary air warmed 

 to HO-; there was no indication of dried edges or 

 "stewed" centres, the leaves being tough and supple, 

 like a piece of very thin leather. I have no exact 

 data, but probably desiccated air at 100' jwould ho 

 about eipnl in withering power to ordinary air at 

 HO." If I am right in this deduction, and 100" is 

 the maximum heat of desiccatcil air that leaf will 

 bear without getting scorched at the edges by the 

 dryness, it would be an interesting comparative 

 experiment to try one batch of leaves with desiccated 

 air »fr lOO"". and another with ordinary air at 110'", 

 and note the ultimate result in the finished tea; 

 persou.al ly , I believe that th(! result would be nearly 

 the same, but there is nothing like a thorough practical 

 trial for setting such questions at rest. It is a great 

 pity that Mr. Main advises the retention of the clumsy 

 old form of wltliering hou.se, for, however much 

 smaller their dimensions, they arc absurdly wrong in 

 principles and will lead to a wanton and woeful 

 Waste of his (!l;sic(^'lted air. If he drives that air itt 

 at the bottom of the chamber flu; first tiers of trays 

 will saturate it and the upper tiers will begin to 

 retake the moisture from below. If at the top, the 

 most valuable and lighter part of such air will cling 

 to the roof, if at the sides the leaves nearest to the 

 sides will get too dry and those further otf be left 

 out in the cold, and wherever and however it is 

 passetl into, or drawn out of, a roomfull of trays 

 the most exposed leaves will take more thau their 



