2 I 2 
[August, 1902.] 
IMPERIAL INSTITUTE JOURNAL. 
Vol. VIII. No. 92. 
the manufacture of many of the commonest artificial dyes, it is necessary to convert the 
alcohol by interaction with other substances into entirely new bodies used as starting 
materials for the dye manufacture, e.g., the preparation of diethylaniline from aniline 
and alcohol costs in England, where duty-paid spirit must be used, 2s. 5|d. per lb., 
whilst in Germany the same chemical can be made from duty-free alcohol for 5|d. per lb. 
Similarly a large number of synthetic products such as sulphonal, phenacetin, antipyrine, etc., 
which are now extensively employed in medicine, cannot be made here for the same reason. 
The annual value of these two classes of materials to the countries in which they arc 
made is estimated at about ,£2,000,000. 
It is satisfactory to find that the representations made by chemical manufacturers to 
the Treasury officials have now led to a promise from the Chancellor of the Exchequer, 
that arrangements will be made to supply manufacturers with duty-free spirit. This con- 
cession appears to have been made with a view especially of encouraging the manufacture 
in England of nitro-cellulose, which enters largely into the composition of modern explosives. 
As an example of the effect which such concessions may have on the growth of industries 
of this class, it may Ire mentioned that, up to the year 1892, manufacturers of tinctures 
and extracts were allowed no drawback on such preparations when exported to the 
Colonies, with the result that export of this class of goods practically ceased, the trade 
being secured by Germany. In that year, however, the Excise authorities began to grant 
a rebate on the alcoholic contents of these goods, and since that time the whole of the 
trade has been practically regained. The new concession now to be given will also no 
doubt have many beneficial effects indirectly, since it should stimulate largely the manu- 
facture of spirit from potatoes, which could be grown profitably on much of the Essex 
marsh land unsuitable for other crops. 
THE PRODUCTION OF MIXED CARBIDES AND 
ILLUMINATING GAS. 
The steady advance in the use of acetylene, especially on the Continent, has led to many 
efforts being made to improve and cheapen the production of calcium carbide, and since the 
chief item in the cost of this material is the electrical energy necessary for its formation Irom 
coke and lime, experiments have, as a rule, been made in the direction of pre-heating the 
reacting materials and so reducing the electrical energy required for their eventual fusion to 
carbide. It is possible, however, to effect a still greater reduction "of cost by manufacturing 
a mixed carbide of lower melting point than the pure calcium carbide. The selection of a 
second oxide to be mixed with the lime in order to form the double carbide is a matter of 
great difficulty, but Professor Lewes, in 1896, found that manganese dioxide was a suitable 
material for this purpose, since the carbide of this metal furnishes, on treatment with water, 
not acetylene but methane, and the latter gas he had previously shown is a most desirable 
addition to acetylene when the latter is employed for illumination, since its combustion in 
burners is thereby rendered smokeless without impairing the high illuminating power. 
Laboratory experiments carried out by Professor Lewes at about that time showed that on 
the small scale it was quite possible to prepare a mixed carbide of manganese and calcium, 
which on contact with water furnished a satisfactory illuminating gas. Subsequently a French 
firm of carbide makers experimented on a large scale with this process, and found that 
carbide could be made by it in about half the usual time and with a saving of about 35 per 
cent, in cost, whilst the quantity of gas obtainable was 10 per cent, greater. These 
remarkable results have induced Messrs. Brame and Lewes to re-investigate this matter on a 
larger scale, and an account of their observations is contained in a paper contributed by them 
to the current number (June 16, 1902), of the Journal of Ike Society of Chemical Industry. 
Using small quantities of materials it was found quite possible to produce the desired mixture 
of carbides giving a good yield of gas, as the following table shows : — 
Mixtures. 
Composition of Gas obtained 
on addition of Water. 
Theoretical Composition 
of Gas. 
Manganese 
Dioxide. 
Lime. 
Coke. 
Methane and 
Hydrogen. 
Acetylene. 
Methane and 
Hydrogen. 
Acetylene. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
50*0 
20 ‘O 
3 °-° 
51-6 
48-3 
44‘0 
55 T 
60 '0 
1 2 ‘O 
30-0 
68 ‘i 
Si’S 
84 '2 
15 ‘8 
637 
8-5 
27 '2 
76‘2 
237 
897 
10 ‘2 
When, however, the experiments were repeated on the manufacturing scale at the works 
of the Acetylene Illuminating Company at Foyers, it was found that with an excess of lime 
calcium carbide alone was formed, whilst, with manganese dioxide in excess, manganese 
carbide was obtained, but no calcium carbide. The following selections from the author’s 
experiments illustrate this peculiarity : — 
Mixtures. 
Composition of Gas actually 
Composition of Gas which 
should have been formed* 
Manganese 
Dioxide. 
Lime. 
Coke, 
obtained. 
Methane and 
Hydrogen. 
Acetylene. 
Per cent. 
59*4 
Per cent. 
12-8 
Per cent. 
277 
f Methane and hydrogen . ) 
( Traces of acetylene . . j 
Per cent. 
66 '2 
Per cent. 
33*8 
Per cent. 
20*0 
44 '4 
35*5 
Acetylene . . . 99^4 
i6’o 
84 ‘O 
8-8 
50-6 
40*5 
Acetylene . . . 997 
6-9 
93 *i 
4 ‘ 5 - 
53 *° 
42*4 
Acetylene . . . 99*2 
3*5 
96*5 
- — 
57 *i 
42 ‘8 
Acetylene . . , loo'o 
XOO ‘0 
There appears to be no advantage, therefore, in mixing manganese dioxide in small 
quantities with the lime and coke for the manufacture of calcium carbide, but it is interesting 
to observe that, judging from the results of the first experiment recorded in the second table, 
it is possible to manufacture in this way practically pure manganese carbide, should a demand 
for this material ever arise. So far the experiments carried out have only included mixtures 
containing less than 20, or more than 50 per cent, of manganese dioxide, and it is possible 
that the required mixed carbide might result if mixtures containing this ingredient in pro- 
portions intermediate to these were employed, and in this direction Lhe authors hope to be 
able to continue the investigation. 
THE AGRICULTURAL AND MINERAL RESOURCES OF NATAL. 
The development of the agricultural resources of Natal, when compared with those of 
other colonies, has progressed but slowly. Many parts of the colony are only suitable for 
pasture land, and, until comprehensive irrigation schemes are undertaken, Natal cannot 
become an agricultural centre ; but now that peace has been concluded in South Africa and 
a Department of Agriculture lias been established, there is good reason to expect, in the near 
future, greater industrial progress. 
The following, summarised from the Natal Directory for 1902, briefly states the present 
condition of the agricultural and mineral resources : — 
Along the coast tea, sugar, and arrowroot grow well, and experiments in coffee-planting 
are being made. Tropical fruits of all kinds grow luxuriantly, and much attention is being 
given to the extension of fruit farms and orange groves. 
In the uplands and midlands the cultivation of peaches, apricots, plums, pears and 
apples, has recently been successfully accomplished. Of cereals, maize or Indian corn 
constitutes the main crop ; oats and wheat are also grown, but the former is used only as 
forage and the latter — grown in the uplands — is subject to rust. The cultivation of barley 
has been undertaken, and so far success has attended the experiment. 
Acacia mollissima or * ‘ black wattle ” grows satisfactorily in many parts of the colony ; 
the bark is used for tanning purposes, and the trunks stripped of the bark are used in 
the mines. 
Tines, cypresses and other conifers, also red and white gums, have been successfully 
grown, and further large tracts of land are to be utilized for planting wattle, gum, casuarinas, 
iron-barks and cedar trees. 
Natal is rich in indications of mineral wealth, for a great variety of minerals are known 
to exist, but with few exceptions the development of these resources is at present insufficient 
to show whether they will prove commercially valuable. 
Coal-mining is a very important industry, the coal occurs in large quantity, and is of 
excellent quality. 
Gold, copper, Iron, nitrate deposits, gypsum and asbestos are the most important 
minerals found within the colony. The former has been discovered at Umzinto and in the 
Tugela Valley and also in several parts of Zululand. Excellent marble quarries have been 
opened in the neighbourhood of the Umzimkulu. 
A Department of Mines has been established, and, although at present mining in Natal 
may be said to be in its infancy, the future will probably see her great natural resources 
properly developed. 
THE UTILIZATION OF BLAST FURNACE SLAG. 
The question of the utilization of blast furnace slag is, in consequence of its increasing 
accumulation, a very important one. Various attempts have been made in this direction, but 
so far its principal use, and that only to a limited extent, has been for making and repairing 
macadamized roads. 
The utilization of slag for artificial flagstones suitable for street- footways and floors of 
buildings has recently been undertaken, and Lhe manufacture of these is described in the 
Scientific American (Vol. bill., p. 21,952). 
Artificial flagstones have already been made by compressing a mixture of granite 
drippings or finely crushed stone and cement. Slag has an advantage over any natural stone 
for this purpose, as it contains a larger percentage of lime and so requires a smaller proportion 
of cement to form an agglomerated mass. The hardness and density of the stones and, 
consequently, their durability, depend to a great extent upon the pressure to which the mixture 
of slag and cement is subjected.. This pressure is best applied by hydraulic power, and the 
press best adapted for the purpose is that known as the revolving- type flag press. This 
machine consists of a heavy revolving table made in the form of a cross, and attached at its 
centre to a fixed circular metal base; each of the arms of the revolving table is constructed so 
that a mould may be easily fixed into position. Two hydraulic rams of different sizes are 
provided, the larger is used for pressing the flagstones and is capable of applying a pressure 
of 4,500 pounds per square inch, and the other is to force the compressed mass from the 
mould. 
The press is so adapted that by one complete turn of the revolving table four operations 
are completed ; the mould is filled with the concrete, which is levelled by a quarter turn of 
the table, then brought under the large ram and compressed, and finally forced from the 
mould by the smaller ram. This mould is then ready to be refilled and, in this manner, the 
four moulds are kept constantly in use. 
ALLOYS OF COPPER AND MANGANESE. 
The process recently devised by Goldschmidt for the production of comparatively 
pure manganese has enabled investigators to experiment more freely with alloys of this 
metal, since it can now be obtained containing not more than 3 per cent, of impurities 
at a moderate price. Although alloys of copper and manganese have been made and used to 
a small extent, very little was until recently known about their physical and mechanical 
properties. This defect is supplied by the data contained in a paper, ( Journal of the Society 
of Chemical Industry, June 30, 1902), contributed by Mr. E. A. Lewis, to a meeting of the 
Nottingham Section of the Society of Chemical Industry. It appears that the addition of 
manganese to copper furnishes a series of alloys of possible industrial importance, so long as 
the percentage of the former is kept below 30; above this amount the alloys become brittle and 
unstable. The specific gravities of the alloys decrease with increase of the manganese 
content, whilst the melting points on the whole rise, although breaks occur in the temperature 
curves between 15 and 40 per cent, of manganese, owing to the formation of a eutectic 
alloy, at these concentrations. The tensile strengths of the metallic mixtures increase with 
the addition of manganese until the content of the latter reaches 26-24 P er cent., when a fall 
occurs. The micro-structure of the copper is not materially altered by addition of manganese 
until about 10 per cent, of the latter is reached, when the large crystals of copper are replaced 
by small crystals of the eutectic alloy of the two metals ; the latter then persists until the 
content of manganese reaches 54 per cent., when a new alloy of remarkable hardness appears. 
The one per cent, alloy of manganese with copper has been employed in locomotive boiler 
tubes and is resistant to corrosion. 

WEST INDIAN TIMBERS. 
( By John T. Rea, F.S.I., Surveyor , War Department.) 
(Continued from p. 184, July Journal.,) 
44. Kakaralli ( Lecylhls ollaria), from the iLoori-bisci creek, Essequebo river. There 
are two kinds common throughout the county of Essequebo, and known as the white and 
the black kakaralli. These woods are close grained and tough, and of a light brown 
colour; they are used for house- framing, building wharves, etc. It is said that barnacles 
will not cat or injure kakaralli. These trees grow tall and straight, but. are too heavy to convert 
into spars. The average height is So feet, and they will square 16 inches free of sap. The 
inner bark of the white kakaralli is used by the Indians as a substitute for, and in preference 
to, paper for making their cigarettes, and is named “ ouina.” 
45. KamarakaTA, from the upper Essequebo river. The tree is comparatively short, 
not averaging more than 50 feet in height, but has a large trunk. It can be had to square 
22 inches free of sap, of which there is very little. it grows in Mahaicony, and on the 
Essequebo in low places near Lhe river (often hanging over the water), and on the islands in 
and above the rapids. The wood is dark brown, close grained, heavy, and of a bitter taste, 
and resembles- Hackia. It is very lasting, and is used for boat timbers, for which purpose it 
answers well. 
46. Karahura, from the Moraballi creek, Essequebo river. It grows generally 
throughout the colony in dry places; its average height is So feet, and it can be had to 
square 30 inches. Karahura is one of the lightest of colonial woods, and is only fit for 
partition boards and other indoor work of a similar nature. The Indians use it for making 
canoes. 
