S44 



THE TROPICAL AGRICULTURIST. 



[February i, 1884. 



could if needful, -be adjusted to a nicety. If all these 

 particulars are carefully carried out in designing a dry- 

 ing-house, the full value of the fuel will be obtained, 

 and t!ie work done speedily and to a certainty. The 

 arrangeraeut of trays, shohes. etc., or travelling webs 

 of cloth (as for tea witheiing), will always depend oii the 

 nature of the products to bo dried. But, as I have 

 noted before, all wnste spaces must be filled up in such 

 a drj-iug-house. Passages there must not be, as lieated 

 air, like almost eveiy other hod)', certainly will move in 

 the direction where the resistance is the least, — it would 

 take an open passage instead of going through \ our dry- 

 ing shelves. Passages can be ent^'cly filled with move- 

 able trays. So not an inch of space need be lost ; and 

 by working the heated air in this manner a uniform 

 movement is secui'ed. 



To save time I must now refer you to the rude plans 

 which I have here. 



1 . — The ground plan shows the position of f ru^ace, flues, 

 and au' drains. 



2. — Another, part of the longitudinal section of the 

 heating apparatus, with drying-house above. 



3. — This plan shows an end view of the whole. 



4. — Plan of air drain (exhaust) and fans with small 

 water motor, for the same. This requires no spur- gearing to 

 get up s])eed, butwill work with a small quantity of water, 

 and a fall of 12 or 15 ft ; and may be erected at small cost. 



To conclude this part I do not pretend to have invented 

 anything new, hut it may be there are some adaptations 

 or ideas brought together, any or aU of which are cap- 

 able of improvement to au indefinite extent. 



TVji. Cajtbeox. 



TEA WITHEEIXG &C. 



1 have now to make a few remarks on tea withering, 

 and the curing of more delicate products than cinchona 

 bark. In regard to bark there is a wide margin to go 

 upon in the matter of temperature — it may be dried slowiy 

 just, so as to prevent mouldiness. or it may he dritd at a 

 tempirature approaching that of boiling water, as the al- 

 kaluids do not decompose till far above that point. Tea 

 withering — a sort of partial drying— requires far greater 

 cai-e. I may note that what I have to state might have 

 come with a better grace and more weight from an ex- 

 perienced tea maker, which I am not, though drifting 

 quickly into that industry. I may also state that it is on 

 the advice of several of our best tea makers that I have 

 ventured to take up this subject ; and as it is only with 

 some of the tea-making apparatus that I am to deal, it 

 does not necessarily follow that I can make tea, good or 

 bad. From all the information gathered during years, 

 from the best authorities on tea-making, it is clear that 

 the whole of the after processes depend on the iirst, or 

 " withering." This ajipcars clear enough when we consider 

 that the withering puts the leaf into a condition suitable 

 or imsuitable for the process of rolling, bruising or break- 

 ing up, whereby the fermentation will he effected. 



Tea uKikcrs all agree tliat in the wet districts at certain 

 times great loss is sustained by the wa.ste of time, and 

 deterioration of the tea by the "withering" failing, from 

 the excessive dampness of the au-. Some siiy that over 

 their furnaces, in wet weather, the process goes on all 

 right, but the limited space at command renders this of 

 little value. Others say heat is bad for the leaf. It is 

 held by some that light is an essential in tea withering. 

 When such differences of opinion exist, it becomes im- 

 possible to reconcile them : the fact is there is likely .some 

 truth in all these conflicting ideas. The result aimed at 

 is the same, and the difference lies in the ideas of the 

 means by which it is brouglit about. Ligl-t is likely a 

 great help to withering, as the leaves go on breathing 

 m the way of plant-lite, after they ha\e been severed 

 from the parent plant; thus facility for parting with 

 water is continued, even if the contents of the leaf-cells 

 are not giadually being altered, even chemically. So let 

 those who wish it have light in their withering-houses ; but 

 in the sort of weather requiring artificial aid the light 

 will be r.ather weak for an appreciable good effect. 



In view of the withering being yet well and correctly 

 done by artificial means, I have put the question to tea- 

 makers, as to what kind of weather the best teas are 

 made ill. The replies have been invariably the finest 

 weather, dry and equable, settled, etc. 



Now iu designing anything to take the place of naturd 

 the safest way is to imitate the laws of nature, or indeee 

 we are but using them all the time, though storing forces, 

 and directing them iu unusual lines, may at first 

 sight falsely appear to be sometbiug more. Isow for tea 

 withering we have to imitate a dry day, not too hot, 

 or some undesirable change may come in your tea. I have 

 now to describe as briefly as possible furnaces suitable for 

 drying air, for withering tea, or di-yiiig cocoa, cardamoms, 

 or other vegetable products; the same in principle but 

 quite different in construction to the cinchona bark drier. 



A furnace for ordinary fnel is required, with brick fiues 

 or metal pipes, or boiler and hotwater pipes, zigzag- 

 ging in a large outer casing. The flues or pipes are to be 

 siirrounde<l with moietm-e-absorbiug materials, such as brick- 

 bats, coral stones. lumps of cbarcoal, &c., any substances 

 which have the property of quickly absorbing moisture 

 from the air. By suitable openings below in the furnace 

 casing the air can be admitted and discharged heated above. 

 But, say, it is not heated air that we want : it is dried 

 air. Well, to get it we must heat up the furnace till the 

 moisture is driven off through an opening to the outer 

 air; then .«hut all openings till the mass of the materials 

 have cooled down by simple radiation of the heat. This 

 may be greatly assisted by thin metal pipes laid through 

 and through the mass. Xow after cooling down, if air be 

 drawn through these absorbent substances it will part 

 with its humidity till the balance is restored and 

 this dried air we purpose to use for tea withering, or 

 other work of the kind. It may be used at the necess- 

 ary degi'ee of humidity and temperature, which ex- 

 perience may determine. I trust I have made my- 

 self imderstood. N'ow to keep up a supply of this dried 

 air, a second or twiu furnace is required, so that while 

 one is in operation the other is cooling down, to be used 

 in s^cces^i^n. The larger these furnace casings and the 

 mass of the absorbents, the more economical will they 

 be, mthin certain limits. This is little draw-back, as the 

 materials are inexpensive. The rough plan which I have 

 here may assist my descrijtiou a little. 



The dryi/iy-house may be built of any suitable materials, 

 wood, stone, or brick, or glass and iron ; but the outer 

 shell must be made as airtight as possible when at 

 work, the ouly openings being those for the admission 

 and discharge of the drying air. 



For saving of labour and to prevent injury to the more 

 delicate products by too much handling, or bruising by 

 being rolled about, the following plan is suggested, and 

 forms au essential feature in the general plan of this 

 drying apparatus, viy.., to fill and discharge the dryiug- 

 house by travelhug webs, instead of using trays, shelves, 

 or t.iblcs filled and tmptied by hand. 



The construction may be a.s follows : — Suitable frame 

 work of wood or iron to be erected, filling the house 

 entirely, save necessary ])assages, which can be tempor- 

 arily shot, when drying is gomg on. 



Tliis frami work is to carry rollers, pulleys!, gearing, &c. 

 for the moving of endless or reversible webs of cloth or 

 other material of open texture, to support the seeds or 

 leaf to be dried. These webs may be of any workable 

 length and breadth. 



The webs at the feeding end are to be mounted — oil 

 rollers— moving for 2 or 3 feet in slots, so, if the rolleic 

 are all pushed inwards, except the lowest, the projection 

 formed by it is the fewling bench for the we'>. Allien 

 charged the next is pulled out to the extremity of the slot 

 in the frame, filled, and so on till the house is charged. 

 AVhen withering or cniirig is accomplished, the webs can 

 be then moved iu the same direction, when the contents 

 will be discharged at the other end, into a suitable receiver 

 for conveyance to other machinerj* if required. The di- 

 stance apart of the webs can be regulated by the bulk 

 of the stuff to be dried, leaving free passage for the air. 

 At 6 iu. apart, a room S ft. in height would give a super- 

 ficial drying area, eqn:d to 16 floors. So the saving of space 

 is secured, fuel and labour being .ilso economized. I liave 

 consulted a gentleman who had the benefit of a scienti- 

 fic training in engineering, in his youth, and lie assures me 

 it will be easy to design suitable gearing, to move the 

 webs for the drying-house, as may be required, and with 

 this reruark I may conclude. 



M'. Causbok. 



