January i, 1891,] 
THE TROPICAL AQRIOULTURI8T, 
Sai 
GEM WASHING PLANT. 
It has been pointed out to us that Engineering of 
April 25th last contained an account of “ Diamond 
Washing Plant,” with a series of engravings which 
afford a very good idea of the machinery employed ip 
excavating, transferring and washing the clay deposit 
in which diamonds are found and which doubtless 
afford some idea of the kind of machinery now being 
sent out by the Ceylon Syndicate to be used at 
Rakwana. The illustrations show the Diamond 
Washing Plant for the Bulfontein, Kimberley and 
De Beer’s mines, and they certainly show the 
elaborate nature of the machinery. From the 
letter-press we quote as follows : — 
The whole machinery is erected on a high bank of 
tailings, levelled for the purpose and connected by an 
inclined tramway with the depositing doors below, on 
which the blue ground brought from the mine is 
caused to pulverise. The trucks containing the pul- 
verised ground are hauled up this incline by an 
endless chain driven by intermediate gear from the 
same engine which drives the rest of the machinery. 
Arriving on the level bank, these trucks run along 
the tramway P and are tipped into the inclined screen 
A, through which the fine ground passes into the 
feeding hopper of the dry elevator B, whilst any 
lumps or stones too large to pass the screen are 
returned along the tramway Q for further exposure 
on the depositing floor. The fine ground lifted by the 
dry elevator is equally distributed between the two 
revolving screens U U, which are slightly inclined, so 
that any lumps too coarse to pass the mesh pass 
out at the euds of the screens, and are similarly 
returned to the depositing floor along the tramway 
S. The screens aro generally formed of stout square 
steel wire, woven into a mesh with | in. openings. 
This is in Bullfontein Mine, where the average size 
of diamonds i/ smaller than in the other mines. In 
Kimberley and De Beer’s mines the mesh is generally 
1 in. square. A spray of olean water is kept play- 
ing on the outside of the revolving screens, and a 
certain quantity is also fed into the hoppers of the 
screens where it meets the dry ground from the 
elevator, so that what passes the mesh of the screens 
is in the form of a puddle and is ready for treat- 
ment in the rotary machines E E into which it 
directly runs. These machines are each 14 ft, in 
diameter, being farmed like mortar mills with an 
inner and au outer rim, the latter about 18 in. high, 
the former about 9 in. In the centre of the machine 
is a stout upright shaft resting on footstep bearing, 
and to tills shaft by suitable attachments are secured 
eight radial arms extending so as almost to touch 
the outer rim of the machine. Bach radial arm 
carries five or six vertical steel tines which are set to 
within about | in. of the bottom of the machine. 
The inlet for the puddle is by an inclined shoot 
from the apron under the screen discharging through 
the outer rira of the machine, whilst the outlet is 
over a weir cut in the inner rim. Since the effect 
of the revolving knives is to throw everything towards 
the outer rim, it follows that all the heavier particles 
tend in that direction, whilst only the light refuse 
passes over the central weir. The speed of the 
machines is about nine revolutions per minute. As it 
occasionally happens through careless feeding, or other 
causes, that diamonds are carried over the central 
weir, the second pair of machines, or safety pans 
F P, which are an exact duplicate of the pans E E, 
receive all the tailings from the latter, and treat them 
over again before they pass through the overflow of 
the safety pans to the wet elevators \V W, which 
deliver them on to the spoil bank. At the top of 
each of these eleva'ois are inclined screens which 
separate the coarse mud from the muddy wafer, the 
latter being returned down the shoots V V to the 
feeding hopper ( f the revolving screens, where it 
mixes with the clean water, and forms a puddle of 
proper consistency, a matter of the groat'-st import.rnno 
as if the water is too olean light atuues accuauilate 
in the machines, raising the level of the deposit 
€6 
therein, whilst if the water is too muddy heavy stones 
may flow away in it, and in either case diamonds are 
liable to be carried over the weir. 
In this connection, and as showing the great 
necessity for the introduction of machinery into 
our gemming districts, we may mention that the 
splendid oatseye recently bought by a Moorman 
and valued at many thousand rupees, is supposed, 
for good reasons, to have been picked up by a 
workman of the Akuresaa Syndicate, who, of course, 
bolted with it, leaving his balance of pay un- 
claimed. The announcement that a large oatseye 
was in the market followed a few days after the 
disappearance of the workman referred to I 
THE DUTCH BARK MARKET. 
Amstebdam, Nov. 26th. — Cinchona. — The sales to be 
held in Amsterdam on Dec. 11th will consist of 4,636 
bales and 135 oases (about 388 tons) Java bark, divided 
as follows : — From Government plantations, 521 bales, 
48 cases about 60 tons ; from private plantations, 4,015 
bales, 87 oases, about 338 tons. Druggists’ bark 
Succirubra quills, 136 cases; broken quills, and chips, 
427 bales ; root, 77 bales ; ofBoinalis, broken quills, 
chips, 62 bales ; Ledgeriana, broken quills and chips, 
2,725 bales ; root, 996 bales; hybrids, broken quills 
and chips, 164 bales ; root, 85 bales. Total, 4,536 
bales, 135 oases. — Chemist and Druggist. 
♦ 
CEYLON UPCOUNTRY PLANTING REPORT. 
PBIZE ESSAYS ON THE FEEMBNTATION OP CACAO — TUB 
WISDOM OP THE WEST INDIES — BDTTERED CACAO — 
ingenuity op THE MOORMAN — HOW TO INCREASE THE 
WEIGHT OP CACAO — ADULTERATION. 
Deo. I7th. 
The Ceylon grower of cacao will receive a new 
sensation if he gets the December number of the 
2'ropical Agrictdturi'it, and reads the “ Prize Essays 
oil the Fermentation of Cocoa,” taken over from the 
Trinidad AgricxUtural Record. 
In Ceylon wo too have had at times a rage for Prize 
essays ; but anything that ever issued here could 
not be compared for a moment with this batch of 
practical beauties, which represent the wisdom of 
the West Indies. They are the nearest things as 
oracular and pretentious deliverances, to the lectures 
which the tea experts used to confound us with in the 
tast, and which weall regarded with becoming awe. 
When I was done with the reading of these West Indian 
essays, and had noted the diversity of opinion which 
existed on the commonest matters of cacao curing, and 
how every man seems to do that which is right in 
his own eye.', and becomes an authority in oonseqnence, 
I could understand how it was that a Commissioner was 
not sent here to learn our method, so that on his 
return he might establish some kind of principle among 
them. As it is they have methods which run from three 
hours to fifteen days ; and the unfortunate who goes to 
these papers for practical guidance will be at his wits’ 
end as to what course to follow. What these AYest 
Indian planters are suffering from is a plethora of 
knowledge, and the crying want among them is how 
they can best unlearn. 
They are nothing if not scientific. Read a passage 
like this : — ‘‘ The vinous fermentation }in this vat 
(No. 1) induced by ‘saccharorayces cerviciie’ is accom- 
panied belo.e removal probably by a cimmenoing 
lactous fermentation, the ferment of which is ‘ peni- 
cillium glauoum 
O, H,, 0,=203 H, O 3 ” 
This is decidedly high feeding, and there is more or 
less of it in all the essays. 
It is hardly to be wondered at that aA class of 
men who are capable of producing the above and 
nnders'amling it have many trade .secrets in connec- 
tion rtilb cacao curing. •' Tansmau," the nom de 
plumo of oue of the writers, surely carries off the 
