IMPERIAL INSTITUTE JOURNAL. 
[June, 1902.] 155 
Vol. VIII. No. 90. 
FORESTRY IN ASSAM. 
The recently issued report on the administration of the forests of Assam during the year 
1 900- 1 90 1, contains some interesting information relative to tire production of timber, rubber 
and other natural products during this period, and illustrates clearly the advantages to the 
State of reserving forest areas, in spite of the opposition often offered to such a policy. 
The extent of reserved forest in this province was not increased during the year 1900- 
1901, the proposed extension of 104 square miles of land in the North Cachar Hills having 
been abandoned temporarily, owing to the existence in this area of numerous villages of hill 
tribes ; in order to exclude these, it has been found necessary to restrict the area of the 
proposed extension to 34 square miles, which will be taken over as soon as possible by the 
Forest Department, 
At the present time only the Goalpara divison is systematically exploited according to a 
working plan, and here in the course of the year 3,420 sal trees were felled, against a 
proposed removal of 5,994, and 5,924 felled in the previous year. The timber of the sal tree 
(Shosea robusta ) is in great demand in all parts of India, and last year the supply could not 
be met in Assam except by the sale of reserve stocks. The working of the forests for timber 
will be greatly facilitated by the use of a portable tramway which was recently purchased, and 
has proved so satisfactory that a 2-| mile extension of it has been sanctioned. 
A portion of the well-known Charduar rubber plantation was again worked over this 
year, the trees in compartments 9, 10 and n being tapped for the first time, and about 100 
trees in compartment 4 for the third time. 
The former yielded on an average, 8'5 lb. per acre and 67 lb. per tree, as compared with 
9 lb. and 6 lb. obtained in the previous year. 
Tapping operations have also been carried out in the Kulsi rubber plantation, where the 
trees tapped for the first time gave an average yield of 28-8 lb. per acre and 1*06 lb. per 
tree. 
This remarkable difference in the yields obtained from the trees of the two plantations is 
accounted for, probably, by the greater age of the Kulsi trees and by the better condition of 
the plantation, which is much more free from shrubs and creepers than the Charduar one. 
The rubber was more carefully collected than in former years, special attention having 
been devoted to keeping it free from vegetable debris. The total yield from the two 
plantations was 3,775 lb. of dry rubber and 1,035 lb. of ‘ mat 1 rubber ; the former brought 
in Calcutta 3s. id. and the latter is. 8d. per lb., whilst 3s. 7d. per lb. was obtained in 
London for the produce of the previous year. The net profit of the rubber-tapping operations 
was about ^440, as compared with ^456 in the previous year. An unsatisfactory feature of 
the Charduar plantation is the great falling off in the yield of rubber from the trees tapped 
for the third time ; unless future tappings show that the trees recover themselves after a rest, 
the value of the plantation as a source of rubber is likely to rapidly diminish. 

GENERAL NOTES. 
OPAL-MINING IN QUEENSLAND. 
Opals have been found in widely separated localities in the western and south-western 
interior of Queensland. They have been mined for in three districts which are about 
equidistant {roughly 500 miles) from the Pacific coast, and hundreds of miles north or south 
of one another. Opal-mining in such situations is a precarious industry, for in dry seasons 
water even for drinking purposes is not procurable within several miles of the mines. The 
work is carried on chiefly by adventurers who alternate this industry with sheep-shearing, 
kangaroo shooting, and job work on stations, and, if favoured with a moderate rainfall and 
fair luck, find the gem-mining highly profitable. The value of the opals obtained in Queens- 
land from 1890 to the end of 1901 amounted to about Zji 16,000. The gem itself is 
pronounced by experts to be unsurpassed for hardness and brilliancy, and has firmly established 
itself beside the best specimens of the Hungarian opal. 
In the southern opal-fields near Thargomindah the gem is found in alluvial ground, but 
in the localities further north it occurs in the rocks of the ranges separating the water-course 
system. In these northern districts the veins or patches of opal are sought by sinking shafts, 
driving and open workings. No machinery is employed, and the gangue is brought to the 
surface in green-hide buckets. Owing to the exceeding remoteness of the opal-fields from the 
coast, and to the intermittency of the mining and the small scale of operations, little official 
attention has been devoted to the industry, and information respecting the occurrence of the 
gem is very meagre. 
A tour of the opal-fields has been made recently by an opal buyer, and an account of his 
observations and experiences is given in The Queenslander (January, 1902). He found that 
operations are greatly hampered by lack of water. Since, however, there are valuable 
resources of subterranean water, he has suggested that the Government should provide wells. 
At Jundah, for example, where at present about forty men are engaged, it is computed that 
if three or four wells were constructed, access would be given to a large extent of country 
capable of supporting three or four hundred men. Under similar conditions, the vast district 
of Eurongella and Eromanga, which now supports 100 to 120 men, could employ 1,000 men. 
The importance of the opal industry is shown by the fact that there are thousands of miles of 
opal-bearing country in Western Queensland ; owing, however, to the drought, the greater 
portion is as yet untouched. > 
ELECTROLYTIC SODA MANUFACTURE IN CANADA. 
A considerable amount of attention has been devoted during the last few years to the 
application of electrolytic methods to the production of metal and chemical products, 
especially in countries possessing abundant sources of water-power, such as Switzerland and 
South Germany, where the electrolytic manufacture of alkali has been successfully estab- 
lished. In America, an alkali factory utilizing electricity developed by the Niagara Falls, 
has been at work for several years, and a new works has quite recently been started at Sault 
Sante Marie, in Ontario, to use power furnished by the Falls on the St. Mary’s river at this 
point. A description of this Canadian installation was given by Mr. B. E. F. Rhodin at a 
recent meeting of the Canadian section of the Society of Chemical Industry, and is printed 
in the current number of this Society’s Journal {April 15, 1902). At the present time the 
methods in use for the electrolysis of sodium chloride on the large scale are of two kinds, 
vis., those employing an electrode of quicksilver, which also serves the purpose of removing 
the metallic sodium as soon as the latter is formed, and so prevents recombination ; and those 
depending on the difference in specific gravities of the solution of sodium chloride fed into 
the decomposing apparatus, and of the solution of soda formed by its electrolysis, which 
prevents the mixing of the two products. 
The Canadian process attempts, with apparently considerable success, to combine the 
advantages of these two systems ; it employs a mercury cathode and a series of gravity cells 
in which soda solution collects of a certain known density, and so produces, as is the case 
generally with the mercury process, a soda quite free from sodium chloride. The installation 
consists of 120 cells, with an output of 9 tons 341 lb. of bleaching powder, and 4 tons 
565 lb. of caustic soda per day, an amount sufficient to cover the whole Canadian demand 
for these products at the present time. No particulars are given regarding the cost of 
materials at the factory, but the cost of electricity developed from the Falls amounts to *o6Sd. 
per lb. ol soda made. In the discussion which followed the reading of this paper. 
Prof. Lang and Mr. Bain drew attention to the advantage held by the Leblanc and Solway 
processes of alkali manufacture over the electrolytic methods, since the former produced 
much less chlorine, and, therefore, did not tend to exceed the market demand for bleaching 
powder, as would soon be the case if the electrolytic methods came into extensive employ- 
ment, in which case a lucrative source of profit would be cut off from the already much- 
reduced revenue of the alkali maker. 
BAUXITE IN NEW SOUTH WALES. 
This mineral, which is the chief source of the metal aluminium, has been found in 
several parts of New South Wales, and in 1899 three of the beds situated nearest to Sydney 
were examined and reported upon by the Government geologist, viz., the deposits at 
Wingello, Inverell, and Emmaville. The attention of American capitalists has recently been 
called to these deposits in a United States Consular Report, which also publishes the follow- 
ing analyses of several specimens of the mineral {Engineer, February 7, 1902) : — - 
Phosphoric 
Acid. 
Alumina. 
Feme 
Oxide. 
Silica. 
Titanium 
Oxide. 
Water. 
Inverell j [ 
Wingello | * 
( Red ore 
Emmaville j Mottled ore 
( Yellow ore 
Small amount 
6-66 
Small amount 
99 J 9 
99 99 
9 9 9 9 
99 9 9 
31 '43 
5S31 
35-28 
39-82 
42-2 
47-84 
28-96 
27-03 
2-85 
1 2 ‘9 
20-34 
28*9 
I 3'59 
l6 - 2 
15- 01 
1-8 
29-3 
10-3 
■16 
1 6 - 4 
35 '5 6 
4 '9S 
2 '4 
21 '65 
5'5 
475 
177 
2-9 
20-38 
32*68 
17'Sl 
22 ‘3 
23*4 
19-2 
I 5‘5 
It will be seen that only one of these bauxites is of high quality, viz., the first Wingello ore, 
and if much of this mineral is available there the property ought, in the future, to prove very 
valuable. 
MINERALS IN THE HIMALAYAS. 
An article in a recent number of the Pioneer calls attention to the mineral wealth of the 
Himalayas, which has hardly yet been touched by mining engineers, and, in fact, has not 
been explored even by the Geological Survey of India. The mountains consist of a central 
range of gneiss and granite, exhibiting rock formations in many parts favourable to the 
existence of minerals. The sands of almost every river coming from the range contain gold, 
indicating the existence of gold-bearing reefs higher up. Graphite of excellent quality, and 
easily mined, has been found, as well as asbestos of good colour and long fibre. 
It is well known that in the past copper has been extensively worked there, and copper- 
bearing rocks are found all over the Kumaon and Garhwal districts. Assays of copper and 
lead ores collected in Kumaon and Garhwal show a considerable amount of silver, and, 
occasionally, gold has also been obtained. 
The climate of the Himalayas in the districts where minerals have been found is usually 
excellent, the land is fertile and labour is plentiful and cheap, while water-power is available 
everywhere. On the other hand, the transport difficulties are considerable, as all goods 
have to be carried by coolies, and any improvement in this direction can hardly be looked 
for until a large industry has been built up. The country is, however, well worth more 
attention at the hands of prospectors, and would probably repay systematic exploration. 
THE FUSION OF QUARTZ IN THE ELECTRIC FURNACE. 
The remarkable optical and mechanical properties of quartz make it a valuable material 
for the construction of physical apparatus, and there is no doubt that if a method of fusing it 
to a transparent solid, free from air-bubbles, could be found, it would very largely replace 
glass for the construction of prisms and lenses for optical instruments. A considerable 
amount of success has already been achieved in this direction by Boys, Shenstoneand others, 
who have used, as a source of heat, the oxyhydrogen blow-pipe, and by this means have 
fused masses of quartz large enough for the construction of small prisms and lenses. 
Mr. R. S. Hutton, of Owen’s College, Manchester, has recently observed in repeating some 
of Moissan’s experiments with the electric furnace that, when finely-powdered quartz is 
heated in the latter apparatus with pure carbon electrodes, it is partially volatilised, but a 
portion fuses to a vitreous transparent solid, and he has found it possible in this way to 
prepare tubes and rods of quartz, the former being very useful for the investigation of the 
behaviour of gases at high temperatures. So far, fused quartz, free from air-bubbles, has not 
been obtained by this means, but it is quite probable that further experience of this process 
will lead to its successful production in masses sufficiently large for the construction of lenses, 
prisms, and other instruments. 
THE ACTION OF SEA-WATER ON CEMENT. 
The disintegrating action exerted by sea-water on cement exposed to its action has been 
made the subject of investigation by M. Le Chatelier, who communicated some of his 
observations to a congress on the testing of building materials, recently held at Budapest. 
{Engineering, April II, 1902. 483). He finds that the magnesium sulphate contained in 
sea-water reacts with the calcium aluminate of the cement, producing a sulpho-aluminate of 
lime, which occupies a greater volume than the simple aluminate it replaces, and produces 
internal stresses in the cement structure by which the latter is slowly broken down. The 
obvious remedy, viz. , the production of a cement free from calcium aluminate, was attempted 
by M. Chatelier, and he found that it was quite possible to replace alumina by ferric oxide, 
a cement of the composition 5 S0 2 , Fe 3 0 3 , 17 CaO, being quite stable in the presence of 
soluble sulphates, and having, moveover, the property of hardening under water like ordinary 
cement. It was also observed that hydraulic mortars were stable in sea-water in inverse 
ratio to the percentage of lime contained in them, and that this stability could be increased 
by the addition of a portion of “ puzzuolana u and that, also, concrete made from finely-ground 
cement lasted better than that made from coarser material, even when the latter was of 
satisfactory chemical composition. 
— — ♦ 
Electric Storage for Automobiles. — A New \ork correspondent of the Times, telegraphing 
on the 28th ult., says It has long been known that Mr. Thomas A. Edison has been experi- 
menting with a view to the invention of a storage battery to enable automobiles to run zoo miles 
without recharging. To-day Mr. Edison announced that he had solved the problem. As soon 
as a 5,000 miles endurance test, which is to be started next week, is completed, he will begin the 
manufacture of storage batteries for the use of automobiles, launches, and street cars. The 
experiments with the new motor already made have been highly satisfactory. It is understood 
that Mr. Edison's invention will also greatly decrease the weight of automobiles. Unlike some 
other American inventors, Mr. Edison is not ib the habit of giving out premature statements 
regarding his successes. Apparently, therefore, the difficulty which has stood in the way of 
the general use of automobiles in the place of horses has been overcome, and an enormous increase 
in the use of motors may be expected. 
