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Journal of the Society of Arts. Proceedings of the Society.
FRIDAY, SEPTEMBER 23, 1904.
All communications for the Society should be addressed to the Secretary, John-street, Adelphi, London, W.C.
"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.
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.
The absence of free fatty acids in edible oils and fats is a very important desideratum. Hence, in all refining processes, the complete removal of free fatty acids and of the objectionable products which seem to follow in the wake of the once formed free fatty acids, namely, those which impart to the oil the properties we comprise under the term "rancidity," is the chief aim of the manufacturing processes. Alkalis and alkaline earths are almost exclusively used for these purposes.
The physical method consists chiefly in filtering, with a view to brightening the oils by the removal of the adhering moisture and suspended matter of an albuminoid character, and, if colouring matter is to be eliminated at the same time, in treating with either charcoal or fuller's earth. The latter process is, of course, followed by filtration, in order to get rid of the charcoal or fuller's earth, which absorb and retain the colouring matters.
A further requisite of edible oils is that they should not congeal at temperatures near the freezing point. Most olive oils practically fulfil this demand. In the case of cotton seed oil, however, which is at present used in enormous quantities as an edible oil, or for adulterating high-class edible oils, a solid portion, termed "stearine," separates out at a temperature of about 50° F., as exemplified by the specimens before you.
In order to render cotton seed oil suitable for the table, this "stearine" is removed; as the technical term runs, the oil is "demargarinated."
Originally the process of "demargarination" was a natural process, and consisted in allowing the oil to stand in large vessels during the winter, when the "stearine" settled out as a solid mass at the bottom of the vessel, so that the supernatant clear oil could be drawn off. Hence, such "stearine-freed" or "demargarinated" oils are designated by the term: "winter oils."
This simple process has, however, become too expensive, owing to the large amount of capital locked up in the enormous quantities of cotton seed oil that had to be stored. Hence, more rapid processes have been introduced. These consist in artificially refrigerating the oil, and filtering off the "stearine" through filter-presses, or removing it by pressure in hydraulic presses. It need hardly be added that in the latter case the whole process must be carried out in artificially cooled
Through the introduction of demargarinating
processes, oils which were objectionable as table oils on account of their separating "stearine," are being added to the range of edible oils. Such oils are arachis oil, and notably that class of Tunisian olive oils which hitherto could not be mixed with the finest Italian and French olive oils, owing to their being exceptionally rich in "stearine."
The industry of edible fats has received, during the last decade, a very great impetus ; notwithstanding its rapid development, this industry is, however, in my opinion, still in its infancy. One of the most important edible fats, butter, claims to belong to the dairy industry. In the interest of the butter industry itself, manufacturing in large establishments should certainly be preferred to the nursing of a kind of home industry under conditions which are not always above suspicion as regards cleanliness. It is just this element which, in addition to the cheapening of food stuffs, has given the enormous impetus to the manufacture of margarine.
The prejudice against this product, which popular ignorance connected with a conglomerate of all kinds of oils and fats, even of fish and train oils and refuse fats, or as a Member of Parliament picturesquely termed it about fifteen years ago, "all the greasy rubbish of the world which is being dumped down in this country," is fast disappearing. If we look at the shop windows of our grocers, it may be said to have already disappeared. The enormous strides which this industry has made are the best possible proof that it has come to stay.
The first and foremost conditions of this industry are the utmost cleanliness and the employment of the purest and freshest materials, combined with the importance of imparting to the product an attractive and even appetising appearance.
From a sanitary point of view, not the slightest objection can be raised against the substitution of cheaper animal or vegetable fats for the expensive cow-butter, and it is rather desirable that this industry should extend, yielding, as it does, cheap palatable food stuffs and thereby tending to exclude from consumption unhealthy fat from diseased animals, prepared under conditions which do not satisfy the most rigorous demands as regards cleanliness.
The origin of the margarine industry dates back to the times of the Franco-German war, when the needs of the beleaguered population of Paris demanded the resumption of earlier
experiments of Mège-Mouriès, which had attracted, a few years before, the attention of the emperor Napoleon.
The fact that butter substitutes lend themselves to fraudulent purposes, as we can unfortunately see every day if we pay some attention to this subject, should be no barrier to the extension of the industry; it is rather the duty of the legislator to render such fraud impossible than to prevent the proper expansion of the margarine industry. Long before margarine made its appearance butter had been adulterated on an immense scale, and the introduction of margarine had a wholesome effect in staying the hands of the adulterator, as the formerly favourite adulterants, such as clay, chalk, gypsum, flour, potato pulp, ground white cheese, and similar substances which used to form the stock-in-trade of the adulterator, have disappeared from the list in order to make room for the harmless, but much less readily detectable, margarine.
Margarine consists chiefly of a mixture of animal and vegetable fats. The animal fats are prepared from the freshest beef fat or hog fat. That obtained from beef fat is known as "" 'oleomargarine," that from hogs -neutral lard- is chiefly employed in the United States. The vegetable oils are cotton seed oil, arachis oil, and sesamé oil. The vegetable oil must be devoid of free fatty acids and should not possess any unpleasant flavour. Thus, neither maize oil, nor even cotton seed oil, can be used for the finest and best brands of margarine, as the particular flavour of these oils would be noticeable in the finished product.
For the production of oleomargarine, the rough fat is removed from the slaughtered animal as quickly as possible and brought into the works, where it is sorted and the kidney fat is selected. This is carefully washed with warm water and thoroughly cleaned. The cleaned fat is then brought immediately into large, well-aired, artificially cooled rooms to dry and harden, being allowed to hang there suspended from tin hooks for several hours. Another process to secure rapid hardening is to immerse the fat first into iced water.
The hard fat is next cut up and shredded in a shredding machine [various types were shown on the screen] and then ground between rollers. The disintegrated mass is immediately introduced into tin-lined, jacketed vessels, at a temperature not exceeding 45° C., this temperature being maintained by hot water contained in the jacket.
In large establishments different kinds of vessels are used, several types of which I exhibit here on the screen.
At the temperature of 45°C., only a portion of the fat contained in the animal tissues separates on the top of the comminuted rough fat. The settling and clearing is assisted by scattering salt cver the surface of the melted fat. This melted portion, appropriately termed "premier jus," is carefully syphoned off and run into clean barrels to be sent to the margarine works proper for further treatment. The "premier jus" is not the whole of the fat contained in the charge, but only the first portion that will exude at a temperature of 45°; the remainder of the fat is recovered from the scraps for other purposes which do not interest us here.
If the margarine be produced in the same works, the "premier jus" is allowed to run into shallow, tin-lined trays, arranged in tiers in a cooled room, when the bulk of the "stearine" separates out in a crystalline condition. For the best qualities of margarine, the "premier jus" is remelted, and allowed once more to settle out, after salt has been added, whereby the last traces of membrane and tissue are precipitated. The cleared fat is allowed to run into large vats, in which it stands from three to five days, at a temperature suitable for the crystallisation of the "stearine."
The crystallised mass from the tins is immediately cut up into small pieces weighing about 3 lbs. each. These are wrapped in canvas cloths, and are then put into hydraulic presses. In large works, where the "premier jus" has been allowed to crystallise in huge vats, the whole crystallised mass is stirred up into a homogeneous pulp which is wheeled to the presses and packed into them in small pieces, wrapped in canvas cloth, holding about 3 lbs. each.
[The "premier jus" presses in actual use in the smallest as well as in the largest establishments were here shown on the screen.]
The oleomargarine-" oleo-oil," as it is termed in the United States-runs out into tanks below the presses, to be worked up for margarine. The solid portion which remains in the presses is sold as tallow stearine.
This oleomargarine is the chief raw material for the manufacture of butter substitutes. It is mixed in special churning machines of the various types I illustrate by lantern slides, with vegetable oils and fats and milk.
The milk department forms, therefore, a
substantial portion of the margarine works. On its arrival from the farms the milk must be "pasteurised." As a rule the cream has been taken off before the milk reaches the works, otherwise it is removed by means of a centrifugal machine.
The milk is run, together with the melted oleomargarine and the vegetable oils admixed in accurately weighed off proportions, into churns, in which the whole mass is thoroughly blended. The churning machines consist of oval jacketed vessels, provided with one or two sets of stirring and mixing gear. During the
process of churning a constant temperature is maintained by means of steam sent through the jacket of the churn. The object of churning, besides thoroughly mixing the ingredients, is to destroy the tendency of the oleomargarine to crystallise, and to produce a complete emulsion by pulverising the mixture into single globules, such as butter fat forms in milk. When the mass is thoroughly churned, the steam is turned off, and the warm material is cooled by cold water sent through the jacket.
so that the mass is completely pulverised. The disintegrated globules, after solidifying, somewhat resemble butter granules.
In small works the cooling tanks are built of marble; in larger works they simply consist of large wooden tanks. In other works they form very large storage vessels, built up of tiles.
From the churn the cooled margarine is run through wooden shoots into cooling tanks. Whilst running out of the churn the margarine is met in the shutes by a current of ice-cold water, delivered under high pressure,
The solidified margarine is taken out by spades, or by long-handled wooden spoons, and placed in wooden wagons, where the admixed water is allowed to drain off. These wagons are carted to large kneading-machines.
They consist of huge, circular wooden tables (Fig. 8), which rotate slowly, whilst at the same time a set of conical, fluted, or speciallyshaped rollers move along the top of the revolving tables. The margarine is slowly but thoroughly worked through, so that the particles become homogeneous throughout the whole mass. At this stage colouring matters are admixed.
The margarine is then salted to taste, and submitted to a further thorough kneading and mixing on a machine similar to the one shown in Fig. 8, or in a specially-constructed churning machine (illustrated by a lantern slide).
The margarine is finally moulded into lumps, pats, rolls, or any other desired shape. [These departments of a margarine works