1030 
THE TROPICAL AGRICULTURIST. 
[June i, 1882. 
numbers, some 350 tons of sugar be expecled. The 
requisite amount of cane is guaranteed by the planters ; 
and, large as the quantity appears, it in little more 
than one ton of cane to the acre of sugar land in the 
district. On good laud the yield is said to be about 40 
tons to the acre, and this the company takes, deliverd 
on the river bank of the various plantations, at a fixed 
rate of 10s. per ton. It is expected that the mill 
will be ready for work in July, 1852, and that the 
planters will then be ready to furnish their quota of 
cane. 
The Rewa River Plantation Company, which has 
done such good service in the past, and whose mill 
is some distance farther up the river, endeavoured to 
secure themselves against their formidable rival by 
refusing to crush for the planters unlefs they would 
guarantee to furnish them with a certain amount of 
cane for a term of years. This caused a quaver of 
consternation among the planters, for, if it had been 
persisted in, it would have involved the loss of the 
greater part of the crop now ripe. Happily, however, 
the company did not persist. Their mill is once more 
in full swing, and the cane is turning out the satisfactory 
density of 10°, a better figure than that which the past 
two years have been able to reach. — Queeslander. 
INDIAN KAOLINS. 
TO THE FDITOR OF THE "MADRAS MAIL." 
Sir, — -Your correspondent "School of Arts" in your 
issue of the 3rd instant I find somewhat obscure in 
the localization of the difficulties experienced hitherto, 
in the working of Indian Kaolins in the manufacture 
of porcelain. He says : — " Now all the Indian Kaolins 
we have tried contained so much silicate in the form 
of silicate of alumina that they cannot mould them 
into shape." Whether by "silicate" is meant the 
proportion of the alumina, or the proportion of silica — 
silicic acid of the silicate of alumina, I am unable 
to follow. If the latter, an admixture of the Kaolins 
in question, with a suitable proportion of the white 
clay occurring in the laterite ridge in the neighbour- 
hood of Cuddalore, known as Mount Cappa, would 
probably give a clay of required composition. The 
clay in question is white viened in parts with red. 
Taking roughly an average sample, no picking out 
of red portion, the analysis obtained was :— 
Sand ... ... ... 41-67 
Combined silica ... ... 15-81 
Alumina ... ... 26 27 
Ferric oxide ... ... 2-51 
Magnesium and alkalies ... 2 82 
Water... ... ... 1100 
100 08 
The amount of magnesium was very small. The 
amounts of potash and soda, constituting in the above 
analysis, the 'alkalies,' I did not determine, as I 
required to use the clay for manufacture of fire bricks 
only. The above clay contained less 'sand and 
' water,' has the composition, 
Combined silica (silicic acid) ... 33 3 
Alumina ... ... ... 55'4 
Ferric-oxide... ... ... 5'3 
Magnesium and alkalies ... ... 6 0 
100-0 
The approximate composition of the silicate of alum- 
ina of this clay, a portion of the iron playing the 
part of alumina, is : — 
A12 03 Si02 
Constituting what is technically known as a "weak" 
clay, wherein the proportion of alumina is large to 
the quantify of silicic acid. By washing the clay, 
the eand could easily be eliminated, together prob- 
ably with a large portion of the alkalies, and iron 
might be largely avoided by picking. Under favor- 
able circumstances, the clay might possibly be re- 
duced to the composition, under these operations of : — 
Silicic acid ... ... 360 
Alumina ... ... 59 0 
Ferric oxide ... ... 2-0 
Magnesium and alkalies ... 3 - 0 
100-0 
a composition which diverges widely from that of a 
porcelain clay, having, in fact, the proportion of silica 
to alumina exactly reversed, so that if, by 'so much 
silicate' chemically combined, "School of Arts," means 
too much combined silica in the clay, a happy mean 
might be struck by mixing the two clays (washed 
and levigated well), resulting in a composition ap. 
proximating that of true porcelain clays, which varies, 
on the dry days, from 50 to 60 silicic acid combined 
with from 40 to 30 alumina, speaking in round 
numbers. "School of Arts" would probably have 
his labours in the search for a porcelain clay much 
lightened, if he had analyses made of those clays, 
which have at all the composition of fire clays, which 
he may come across, and probably in the con- 
sideration of these analyses he would find useful, a 
paper, on "Chinese Porcelain Manufacture" by A. 
Heintz Dengler's Polytechnical Journal, CCXVI, 156, 
66, appearing in an abstracted form in the Journal of 
the Chemical Society, Vol. II, 1876, page 671. 
In this abstract the analyses of two China (I and 
II) and of two French (III and IV) porcelain clays 
are given as follows : — 
Loss by ignition (almost wholly 
water) 
Silicic acid 
Alumina 
Ferric oxide 
Lime 
Magnesia 
Potash 
Soda 
I. 
II. 
III. 
IV. 
11-2 
8-2 
12-6 
7-2 
50-5 
55-3 
48-3 
56 9 
33-7 
30 3 
35-0 
31-6 
1-8 
20 
1-3 
0 5 
0-5 
0-8 
trace 
04 
1-9 
2-4 
3-8 
3 4 
Yours &c., 
F. N. G. Gill. 
ORANGE TREE CULTIVATION. 
The following facts as to orange cultivation at the 
Azores, communicated in a letter to an Australian 
contemporary, will throw some light on the causes of 
decadence in the tree and the means of preventing it : — 
Until 1836 the orange trees budded, blossomed, and 
fruited with unvarying regularity. The grower would 
as soon have suspected the sun of variation from his 
diurnal course as the orangeries from their yearly round 
of duty. They were handed from father to son, and 
lasting as they did from generation to generation, it 
is not surprising that they became a symbol of perman- 
ence. These trees cost the growers no care, no 
attention, no labour, save the labour of picking and 
packing, so far as we can understand. The people 
might dance and drink the year round, and the orange 
would blossom and fruit the year round, without trench- 
ing, without manuring, without draining— it may be 
without pruning. The plant was neither fickle nor 
fastidious, and the islanders rejoiced in their orange 
trees. Suddenly, however, there came a change. 
This bright piclure of the growing, greenleaved, self- 
contained tree, surrounded by a joyful, sun loving, 
dancing people, dissolves away, and gives place to a 
pale-leaved and sickly tree, surrounded by a carefaced 
and inquiring population. Their first proceedings were 
those of the panic-stricken, they were carried to ex- 
tremes. From absolute indolence they rushed into 
