Puslapio vaizdai
PDF
„ePub“

Many

Royalty was paid at the Department of Lands and Mines on 101,325 ounces for the year ending June, 1903, while for the same period ending 30th June, 1904, royalty was paid on 87,442 ounces. The reasons for this falling off are not far to seek. of the smaller placers, which had been formerly worked systematically, have either been abandoned or been handed over to the rough and ready methods of the "maraudeurs." Local capital has not been forthcoming to any extent, and any influction of outside capital has been directed either to quartzmining, diamond mining, to the revivication of mining proper, or to hydraulicking. With regard to the latter, it must be remembered that topographical difficulties have had to be overcome by the importation of machinery on a large scale, and that therefore the expected results have not gone to swell the returns of the past year.

When we come to examine in detail the production of the various districts, we find that the Barima district shows a falling off of nearly 3,000 ounces, the Barama of nearly the same amount, and the Cuyuni 3,910 ounces. The Puruni shows a small decrease of 435 ounces; probably this would have been greater had it not been for the working of the Peters' Syndicate, which have not been alluvial in the proper sense of the word, the gold being derived from quartz crushed by hand-power. The Mazaruni shows a decrease of over 1,000 ounces, while the Essequebo alone enjoys the distinction of showing an increase of 571 ounces, due to the workings at Omai, a striking exemplification of the superiority of systematic working. The Potaro shows a decrease of 3,358 ounces, which is only to be compared with that of the Cuyuni, a river which shares with it the reputation of being worked to a great extent by undirected and unsystematic methods.

It is not to be concluded by any means that this falling off is any indication as to the possibilities of the colony, even alluvially, as it is the consensus of opinion amongst experienced and trained mining engineers who have made thorough investigations during the past year that the resources of the country from the point of view of gold are practically untouched, and that the fluctuations in the production of small workings in the creek beds and flats cannot be taken as any indication of the enormous amount of alluvial existing in the spurs and slopes of the hills which ought to give a good return for scientific and up-to-date working for many years to come. It has been stated by a geologist of repute, Dr. Lungwitz, that in one district prospected by him there exists a layer of auriferous gravel extending for some twentytwo miles, and having a width of half a mile and a depth of two to three feet. He estimated that every cubic yard of this gravel carried about 6s. 3d. worth of gold to the ton, and with power existing by which it could be cheaply worked from the neighbouring falls. Professor Harrison, the Government geologist, has also given his opinion that the iron-capped hills of the Essequebo and Potaro districts should prove a

come.

source of wealth to the colony for many years to Mr. Linck, an experienced mining engineer, says that the alluvial auriferous deposits have so far scarcely been touched. Up to the present, only the beds of the streams carrying only a little water, have been worked by the "pork-knockers" with the crudest of appliances, and in other cases by small syndicates whose appliances for handling dirt are little ahead of the pork-knockers. There is no doubt that in the known gold-fields, the more easily worked creeks have been practically exhausted, thus accounting for the falling off in the gold out-put of the colony. Attention must now be directed to working the auriferous deposits on the slopes of the hills, which, there is no doubt, occur in large areas and only want capital to develop. In many parts of the gold-fields water can be conveyed on to these alluvial deposits by means of ditches, while in others it would be necessary to pump the water to work the ground as is done by the Omai Gold Mining Company, which is working very profitably deposits of gold-bearing wash, that it would be impossible to get water on to otherwise than by pumping machinery. But it is doubtful as to whether many of the claims which are now being systematically worked could not be made to pay should some impetus be given to the outlay of local capital in the direction of affording the small capitalist some assurance that his interests would be safeguarded, and that his gold would not be stolen, his provisions wasted and the labourers induced to desert their employer, lured away by, to them, the superior attractions of "maraudage."

Diamonds.-The export of diamonds for the past year shows a slight increase over that of 1902-3. During the year ended 30th June, 1903, 10,559 carats weight, valued at 96,190 dols., were exported, and during the same period of 1903-4, 11,200 carats, valued at 92,431 dols., were exported. The number of stones declared at the Department of Lands and Mines for the past year was 167,296, weighing 11,303 carats, but it is extremely probable that the shipments for July will be much greater than for any previous month in the year. There have been some suggestions made as to the amalgamation of some of the companies with a view to lessening the cost of transportation and management. The former question, that of transportation, is still a great drawback to the industry, and if some means can be devised of lessening the cost of taking up provisions over the falls of the Mazaruni an undoubtedly great impetus would be given to this growing and important industry. The number of labourers registered for the Mazaruni diamond fields during the year was 1,145.

Forest Products.-The amount of balata exported from the colony during the past year shows 547,601 lbs. as against 490,174 lbs. for the preceding year. Timber showed a slight decrease, 304,881 cubic feet being exported, as against 319,438 cubic feet for the preceding year. Shingles were exported to the value of 94,112 dols., or an increase of 3,988 dols. over 1902-3; firewood to the value of 11,849 dols. as against 2,275

[ocr errors]

dols.; and gums 11,549 lbs. as against 6,558 for 1902-3. Charcoal, 80,800 bags, to the value of 40,575 dols., were exported, as against 74,383 bags, valued at 58,621 dols., for 1902-3. It would thus appear that the minor forest industries of the colony are capable of considerable expansion, and that a large market exists in the West Indies themselves for charcoal, hardwood and shingles. These industries appear to be almost altogether confined to the Demerara River, and indeed would seem to be the staple industries of that district. It would be interesting to know the number of persons employed in these various industries, which aggregate apparently an export of 342,947 dols., in addition to the value of the timber, shingles, firewood and charcoal retained for home consumption. It would scarcely be going too far to suppose that something like three times the amount exported is consumed in the colony.

Questions of labour, prospecting licences, unregistered labourers, &c., are also discussed in this Report.

THE TOWN HOUSING QUESTION.* The fundamental difficulty of the question is the growth of town populations which have been housed without any regard to hygienic conditions.

There are two main aspects of the problem: (1) the sanitary aspect, i.e., the existence of slums and insanitary areas; and (2) the house famine. This, again, is of two kinds: first, and more rarely, a house famine due to special circumstances, e.g., when the sudden growth of an industry causes an abnormal increase of population; second, a constant difficulty as to the supply of cheap houses. Increased cost of building has not checked the growth of superior house accommodation, but has interfered with the production of cheap houses, while improvements remove the old inexpensive cottages. Hence there is great pressure on those which still exist.

How have local authorities attempted to cope with these difficulties ?

1. In the case of insanitary areas they have used Part I. of the Housing Act; in the case of small groups of bad houses improvements have been effected by Part II. and by the Public Health Act.

2. The preventive and regulative work of the sanitary authorities has done much, and might do more, to improve bad conditions and to stimulate healthy effort.

3. Lastly, there have been attempts to deal with the house famine by means of municipal house building and owning. There are several different policies with regard to this.

(a.) The Liverpool policy of cheap tenement houses on central sites, the object of which is to rehouse the very poorest classes who now occupy court houses.

Abstract of paper read by Mrs. Fisher before Section F. of the British Association at Cambridge.

The results are interesting, and there are many arguments for and against it. Various devices have been attempted in order to secure the occupation of municipal houses by the really poor.

(b.) Some advocate the plan of building ordinary houses or tenements in large number in order that municipal competition may lower the level of rents. The results of this are slight.

(c.) Recently attempts have been made to develop suburban estates. This seems hopeful, but there are many difficulties, especially as to providing for the very poor on such estates.

The main task of house building must be left to private enterprise; the duty of local authorities is to urge private enterprise to do the very best that can be done. There are two main ways of bringing this about: (1) By wise building by-laws properly enforced; (2) by thorough administratiou of the sanitary laws. These two duties are at present very imperfectly performed. The urgent necessity of guarding suburbs and new districts is not yet realised.

Local authorities have experienced great difficulties, especially financial difficulties, as to their building schemes, but recent developments seem more hopeful. Local authorities ought (1) to make experiments, lead, and suggest (examples, Sheffield and Camberwell); (2) in cases of monopoly create competition; (3) where necessary deal with classes which cannot be left to private enterprise, but great caution is essential to the success of such plans.

THE ELECTRICAL CONDUCTIV CONDUCTIVITY OF CERTAIN ALUMINIUM ALLOYS AS AFFECTED BY EXPOSURE TO LONDON ATMOSPHERE.*

This paper deals with the effect upon electrical conductivity of exposing light aluminium alloys to London atmosphere. During three years' exposure the copper-aluminium alloys have gradually diminished total conductivity to a greater extent the greater the percentage of copper. The nickel-copper aluminium alloys, which show such remarkably increased tensile strength as compared with good commercial aluminium, have during the last year considerably diminished total conductivity. On the other hand, the manganese-copper aluminium alloys have suffered comparatively little diminution in total conductivity, and one of them has comparatively high tensile strength. It was thought that an examination of the structure of these alloys by aid of microphotography might throw some light on the great difference which exists between some of their physical properties. For instance, a nickel-copper aluminium alloy has 1.6 time the tensile strength of ordinary commercial aluminium. Under a magnification of

Abstract of paper by Professor Ernest Wilson, read before Section G of the British Association at Cambridge,

800 diameters practically no structure could be discovered. Considering the remarkable crystalline structure exhibited by ordinary commercial aluminium near the surface of an ingot, when allowed to solidify at an ordinary rate, the want of structure in these alloys must be attributed to the process of drawing down. The inference is that the great difference which exists between their tensile strengths and other qualities is not due to variation in structure. The experiments in micro-photography have been carried out by aid of a portion of the Government grant voted to me by the Council of the Royal Society.

Notes on Books.

SIX LECTURES ON PAINTING, delivered to the Students of the Royal Academy of Arts, January, 1904. By George Clausen, A.R.A., Professor of Painting. London: Elliot Stock.

The author, in considering the present position of the Fine Arts and the adverse circumstances of the times, refers to an anecdote of the condition of painting in the early days of the art which is related by Lanzi. Orcagna, in the first quarter of the fourteenth century, asked the question of his companions, "Who was the greatest master, setting Giotto out of the question?" Some answered Cimabue, some Stephano, some Bernardo, and some Buffalmacco Taddeo Gaddi said, "Truly these were very able painters, but the art is decaying every day." Mr. Clausen considers this to be comforting and that it shows how the relation of the artist to the world in general was always much the same as it is now. After an introduction on some early painters the subjects of the several chapters are Lighting and Arrangement," "Colour," "Titian, Velasquez, and Rembrandt," "Landscape and Open-air Painting." concluding with Realism and Impressionism."

[ocr errors]
[ocr errors]

A TEXT-BOOK ON CERAMIC CALCULATIONS, WITH EXAMPLES. BY W. Jackson. London: Longman's, Green, and Co.

The author has not attempted to write a text-book on pottery manufacture but to give help to classes in pottery and porcelain by printing a collection of examples showing the application of mathematical and chemical methods to the consideration of the problems presented for solution in the course of the manufacture.

THE ANALYSIS OF OILS AND ALLIED SUBSTANCES. By A. C. Wright, M.A., B.Sc. London: Crosby Lockwood and Son.

The author's intention has been to present an account of the methods used in the analysis of oils, lats, and waxes in a form suited to the needs of the

student and beginner, while at the same time including all recent developments likely to be found of value in practical work.

The chemistry of the various processes has therefore been set out in some detail, and methods which have been recently proposed are fully explained. A good deal of space is given to a description of the properties of the more important oils, fats and waxes, with the method for their investigation.

There are also chapters on the physical and chemical properties of oils and fats, as well as on the methods for estimating their constituents.

A RECORD OF THE INTERNATIONAL FIRE EXHIBITION, EARL'S-COURT, LONDON, 1903. By Edwin O. Sachs, Chairman, British Fire Protection Committee. London.

This volume contains a fully illustrated account of the proceedings at this important Exhibition, which was held last year, and a description of the exhibits. Special attention is given to the remarkable Loan Exhibition, in which were shown interesting historical objects relating to Fire Prevention, Fire Protection, Fire Insurance, and Fire Literature, also Portraits and Models, Monuments and Mementoes of Fire Heroes and Worthies, Pictures of Fires, Commemorative Medals, &c. The Collection of English Antiquities was fully supplemented by special foreign exhibits from France, Germany, Holland, Italy, and Russia. The editor claims that the particulars of the collection will serve as an outline of the history of fire extinguishing during the last three centuries, more particularly if studied in connection with the notes of Chief Officer Graham, of Hampton, who was responsible for the correct execution of the Historical Pageant in the Exhibition Theatre.

IMPERIAL INSTITUTE OF THE UNITED KINGDOM, the Colonies, AND INDIA. Technical Reports and Scientific Papers. Edited by Wyndham R. Dunstan, M.A., F.R.S. London.

The Reports refer to Coal, Iron Ores, and various Minerals, Fibres, Oils and Oil-Seeds, Rubber and Gutta-Percha, Gums and Resins, Medicinal Plants and Tobacco, Tanning and Dyeing Materials, Fodder Plants and Food Grains, Timber, &c. The scientific papers are devoted to important chemical investigations respecting the technical value of materials sent to the laboratories of the Institute.

THE ELECTRO-PLATING AND ELECTRO-REFINING OF METALS. By Alexander Watt and Arnold Philip, Assoc. R.S.M., B.Sc. London: Crosby Lockwood and Son.

This is a new edition of Alexander Watt's wellknown work on "Electro Deposition." The present edition is divided into two parts: Part I. on ElectroPlating, and Part II. on Electro-Metallurgy. Mr.. Philip has contributed some two hundred and twenty pages of fresh matter, including chapters on the cost of electrolytic copper refining, and on some important details in electrolytic copper refineries.

Journal of the Society of Arts. Proceedings of the Society.

[blocks in formation]

"OWEN JONES” PRIZE.

This competition was instituted, in 1878, by the Council of the Society of Arts, as trustees of the sum of £400, presented to them by the Committee of the Owen Jones Memorial, being the balance of subscriptions to that fund, upon condition of their expending the interest thereof in prizes to "Students of the Schools of Art who, in annual competition, produce the best designs for Household Furniture, Carpets, Wall-papers and Hangings, Damask, Chintzes, &c., regulated by the principles laid down by Owen Jones." The prizes are awarded on the results of the annual competition of the Board of Education, South Kensington.

Six prizes were offered for competition in the present year, each prize consisting of a bound copy of Owen Jones's "Principles of Design," and a Bronze Medal.

The following is a list of the successful candidates :

Rudge, Margaret M., Battersea Polytechnic School of Art, London, S.W. - Design for Printed Muslins.

Lavington, Clara, School of Art, Leeds.- Design for Embroidered Screen.

Harford, Ida, Battersea Polytechnic School of Art, London, S.W.-Design for Printed Muslin. Metcalf, Arthur, School of Art, Carlisle.- Design for Tiles.

Pickford, Percy, School of Art, Macclesfield.-Design for Tile Panel.

Oldfield, Arthur, School of Art, Macclesfield.-Design for Silk Hanging.

The next award will be made in 1905, when six prizes will be offered for competition.

CANTOR LECTURE.

OILS AND FATS-THEIR USES AND APPLICATIONS.

BY DR. J. LEWKOWITSCH, M.A., F.I.C. Lecture II.-Delivered February 1st, 1904. We have seen in the last lecture how the raw oils and fats are prepared by modern methods. The oils and fats thus obtained are in their fresh state practically neutral. If care be exercised in the process of rendering animal oils and fats, the fatty matter is very often sufficiently pure to be immediately worked up in those industries to which they serve as raw materials. If, however, they are allowed to remain in contact with animal tissue, they are liable to very rapid deterioration. Thus, freshly rendered lard or suet, or even whale oil, will keep sweet for a very long time if protected from light, air, and moisture, whereas the same materials through prolonged contact with putrescible animal matter become dark in colour, and rich in free fatty acids. This is especially exemplified by the five samples of whale oil shown here. Of these, whale oil "No. o," is perfectly sweet and water white, whereas the lower grades passing through whale oil "No. 1" to "No. 4," become gradually darker, and finally acquire an offensive odour, in consequence of having remained in contact with the flesh and bones for a somewhat prolonged time.

The vegetable oils obtained by expression contain frequently mucilaginous matter and other impurities, such as vegetable fibres, which pass through the press cloths. There are also admixed with the oils traces of moisture, which render them somewhat turbid, dark, and unfit for immediate use; not only for the table, but also for manufacturing purposes. Formerly these impurities were removed from edible oils, such as olive oil, by the simple method of allowing the oils to rest for some length of time, when the moisture and the mucilaginous matter, &c., would settle out. This crude process is no longer employed in large establishments, the clarifying of the oils being much shortened by filtering through a filter press, or brightening by blowing with air.

Other crude oils require more elaborate purification (refining) before they are placed on the market. Notable examples of this kind

are cotton seed oil and rape oil. The sample of Egyptian crude cotton seed oil I show here has been expressed direct from the crushed seed. It ranges from a ruby red to almost black colour, due to the deep dark brown colouring matter contained in the cells of the cotton seed. The oil is refined by treatment with dilute caustic soda; the latter combines with the colouring matter and the free fatty acids in the oil and forms a precipitate which falls down on standing, leaving the oil clear and bright. This crude rape oil, again, is refined by treatment with concentrated sulphuric acid, and yields the refined oils shown here. From these two examples, which can be multiplied by the series of other oils which you have before you, both in the crude and refined state (linseed, castor, fish, sperm oils, and various rape oils, &c.), it may be gathered that the processes adopted on a manufac turing scale vary greatly with the nature of each individual oil or fat.

The methods of bleaching or decolourising oils also vary with each kind of oil or fat. Time permits only of a brief glance at the methods employed on a large scale.

Bleaching by sunlight, one of the oldest processes, is naturally only feasible on a small scale, as the length of time and the space required to expose as large a surface as possible must naturally be costly. Still, in some cases, as in the bleaching of beeswax or in the bleaching of linseed oil for artists' use, this method is being practised. Since the fatty matter undergoes practically no change, the products do not suffer as much as they would in the chemical processes of bleaching.

Bleaching by the aid of chemicals requires great circumspection, the object of bleaching being merely to destroy foreign substances, which impart a dark colour, or other undesirable properties to the oil or fat. The chief attention of the operator must therefore be directed to so treating the raw material that the fatty matter itself is not acted upon. For this purpose, the amount of chemicals must be limited to the smallest possible quantity, the temperature at which they are allowed to act must be as low as possible, and the time of interaction must be as short as possible.

General methods of bleaching chemically, are (1) Bleaching by means of oxygen; (2) bleaching by means of chlorine.

(1) Bleaching by means of ozone or oxygen gas is still too uncertain a process to be widely used on a large scale, and is only practised in some special instances. I have examined

several ozone processes, but although at the first moment they seemed to effect the bleaching satisfactorily, yet after a time the colour of the oils darkened, or as the technical term runs, "reverted."

Bleaching by means of oxygen in statu nascendi is chiefly effected by employing manganese dioxide or potassium bichromate and sulphuric acid.

(2) In the processes of bleaching by means of chlorine, bleaching powder, or potassium bichromate and hydrochloric acid are used.

No general rule can be laid down as to which process should be employed in each given case, although it may be stated that tallow is best bleached by means of manganese dioxide, and palm oil by means of bichromate and hydrochloric acid.

The object of bleaching is not only to remove colouring matters for the time being, but to remove them so efficiently that the colour, or even a dark shade, will not "revert" some time after the fat or oil has been bleached. Patents claiming to effect this object appear annually in great numbers, and disappear again when experience has shown that the colouring matter does "revert" to a larger or smaller extent after the material has, e.g., been converted into soap. Thus one of the simplest and most frequently practised processes, that of bleaching tallow, does not produce soaps as good in colour as those made from the freshly rendered tallow. Not only must each kind of fat or oil be considered a special problem, but frequently different varieties of one and the same oil are apt to cause the same difficulties as would a new oil or fat. To mention an example, the bleaching of the softer kinds of palm oil, such as "Lagos" or Old Calabar," offers very little difficulty. But the harder kinds of palm oil, such as Congo oil, have hitherto withstood all attempts to bleach them.

The above methods of bleaching are, however, inadmissible in the case of those oils and fats which are tendered for edible purposes. In these cases we must rely chiefly on physical methods. The oils intended for edible purposes must not even be expressed while hot, and the employment of chemicals involving the use of acids must be altogether excluded, as they impart an objectionable flavour which would render the product useless for edible purposes. Treatment with alkalis in one form or another can only be resorted to in a very moderate degree as, for instance, in the refining of cotton seed oil for the table.

« AnkstesnisTęsti »