Search results

Economics of surface coatings on metals are discussed with emphasis on surface preparation, especially when large scale coating operations are conducted. Relative cost and other parameters affecting the choice between manual and machine blasting are considered, including the area cost of surface preparation, health and safety factors, incidental pollution, and other variations. Advantages of high build surface and multi‐purpose primer application are related along with comparisons of cost between initial and manual recoating of structures after erection. Importance of proper coating maintenance is emphasised. Economic case histories are given, including large scale surface preparation of tank plates and piping, differences between sand abrasive and centrifugal blasting, factors related to intercoat adhesion, cost of Zn rich with epoxy or alkyd topcoats, and the high cost of repainting when scaffolding is necessary. Regulations on surface preparations, ecological controls, and safety are discussed. Two coat simplified systems are recommended, along with automatic and semiautomatic surface preparation when the size of the job makes either one possible. Tabulated data on area costs of various modes an locations for surface preparation and coating costs for various metal configurations are provided.

The relatively complex corrosion mechanism of aluminium has been studied by several authors. Corrosion of aluminium occurs only when the metal protective oxide layer is damaged and when the repair mechanism is prevented by chemical dissolution. Polarization methods have been extensively used to investigate the mechanism of localised corrosion and processes that lead to localised corrosion. The potential‐pH diagrams are shown in Fig. 1A. In using potentiostatic techniques, the potential is controlled and current is determined as the independent variable. Potentiostatic and potentiody‐namic techniques have been applied by several authors to study the corrosion of aluminium in different environment. Both anodic and cathodic polarization curves have been used to interpret the kinetics of pitting corrosion of aluminium in chloride containing environments. Both the anodic and cathodic process are complex and the interpretation of the anodic and cathodic polarization curves of aluminium is often tedious. The situation arises partly from the fact that the role of film formation on the kinetics of corrosion is not clearly understood. Previously there is not established mechanisms of initiation and propagation of pits in aluminium and its alloys. Several parameters such as pitting potential, breakdown potential, active passive transition potential, related to the pitting process of aluminium, are full of controversy. Numerous references on the above can be found in literature).

The discovery of the Hall‐Herqult process for the manufacture of aluminium made it possible to obtain the metal in large quantities. Soon it attained the position of a major industrial metal due to its lightness combined with strength, capacity to take up a high polish, excellent conductivity of heat and electricity. Moreover it gives a wide range of extremely valuable alloys with diverse elements such as copper, magnesium, nickel, silicon, zinc, etc.

Introduction Amines have been known for a number of years as effective corrosion inhibitors. Their efficiency is attributed to the presence of the nitrogen atom acting as the active centre for the adsorption of organic molecules on the metal surface. Several aliphatic and aromatic amines have been reported to serve as effective corrosion inhibitors for iron and steel in acidic solutions. The nitrogen‐containing corrosion inhibitor exhibited a very good performance in hydrochloric acid, but very little effect in sulphuric acid. Hence a study of the mechanism by which the corrosion rate is reduced when these organic compounds are added to solutions is of interest. In this study the inhibition of corrosion of mild steel in HCl and H2SO4 has been studied using different electrochemical techniques. Results are reported and discussed.

Introduction The sulphonate molecule has become one of the most versatile surface active chemicals available to industry. Its value as rust or corrosion inhibitor in a variety of areas has been demonstrated many times over in field and laboratory tests. A review of these various applications has been published.

THE occasional moving of stock in open‐shelf libraries creates a sense of novelty in the reader. We experienced this recently in entering a library familiar to us where we found the Literature section had been moved and reduced in order to make space for the increase in the Applied Arts class. Further the librarian declared that there was no excessive demand for much of modern poetry, but although the library has the poems of T. S. Eliot in several copies, none was on the shelves or at the moment available. One wonders if poetry that is “modern” has been read by the majority in the past half‐century; it is an art form, often lacking substance and therefore caviare to the ordinary reader. The poets of today with such exceptions as Walter de la Mare and Alfred Noyes, neither of whom is young, have not increased their chances by their deliberate or unconscious obscurity. Even the said‐to‐be most influential of the modern, T. S. Eliot, in such a work as Ash Wednesday, topical this month of course, is completely unintelligible, in spite of the almost divine music of some of its lines, to many quite intelligent and habitual readers. Our librarian declared that readers remain for Coleridge, Keats, Shelley, Tennyson, Browning and even for Longfellow, in short for the real classics. This conclusion is borne out by the examination of a day's borrowings a year ago at Manchester. “Modern poetry,” its Report tells us, “seems to be departing from the range of the general reader into some esoteric mystery of its own,” and while the older classics, Browning, Chaucer, Donne and Tennyson were borrowed to the extent of four copies each, other poets were less in demand. Altogether 21 works of individual poets and 16 anthologies went out that day. A small array but, if continued through the year, it meant 11,100 works which are not a negligible number.

DESPITE the critics who arise to condemn the onward march of the Public Library movement there can be little doubt that after the settling process has been gone through it will be more seriously reckoned with as a factor within our social evolution than at present; and meantime it were well to remember that fine definition of Dickens in regard to the Public Libraries of fifty years ago, and to see whether it was a prophecy or a realisation when he said, “It is grand to know that … the immortal mechanism of God's own hand, the mind, is not forgotten in the din and uproar, but is lodged and tended in a palace of its own.” Let us extend the meaning and see how the Public Library movement has grafted itself upon the mind of the great public by whom it is supported, and how it stands in regard to the authorities by whom it is controlled, and then, taking this position, let us ask the two questions: “How does it express itself popularly, and do people look at it in the light which Dickens did?”

ANOTHER Annual Meeting has come and gone. It was scarcely to be expected that the meeting at Bradford would be a record in the number of members attending, seeing that it is only three years ago since the Association met in the neighbouring city of Leeds, and that Bradford cannot boast either the historical associations or the architectural and scenic setting of many other towns. For the most part therefore the members who did attend, attended because they were interested in the serious rather than the entertainment or excursion side of the gathering, which was so far perhaps to the advantage of the meetings and discussions. Nevertheless, the actual number of those present—about two hundred—was quite satisfactory, and none, we are assured, even if the local functions were the main or an equal element of attraction, could possibly have regretted their visit to the metropolis of the worsted trade. Fortunately the weather was all that could be desired, and under the bright sunshine Bradford looked its best, many members, who expected doubtless to find a grey, depressing city of factories, being pleasingly disappointed with the fine views and width of open and green country quite close at hand.

Hitherto, we have discussed the advisability of issuing a magazine, and have entered with some degree of minuteness into the underlying financial principles; we now have to consider the arrangement of the contents. So much controversy has raged over the question of classified versus dictionary or alphabetical cataloguing, that it will be unnecessary to recapitulate the pros and cons. On the whole, the classified method has met with most favour, and experience has taught us that it is undoubtedly the better for magazine purposes. In this, we are in accordance with nearly all librarians publishing magazines. Indeed, in magazine work, where as a rule only one entry is given to a book, the alphabetical method is inadequate. It resolves itself into an alphabetical list either under authors' names, or under catchword subjects which is useless in showing the relation of one book to another. A properly classified list—preferably classified according to some recognized systematic scheme—on the other hand, displays the accessions to the library much more effectively, and does fulfil the necessary function just mentioned.

One can easily see that there is abundant opportunity for the introduction of harmful impurities unless every care is taken to avoid contamination due to impure ingredients or by metals, if used, in the plant. The Departmental Committee already referred to considered that the maximum permissible quantity of arsenic in any colouring substance used for food purposes should be 1/100th of a grain a pound, and that the total amount of lead, copper, tin and zinc should not exceed 20 parts per million. Thus a dyestuff should be of a high degree of purity in spite of the fact that it is only added in very small proportions to food. In America the Food and Drug Authorities issue certificates for each batch of dyestuff after it has passed thorough physiological and chemical tests. There is no doubt that if such tests were carried out in this country by officially appointed chemists and physiologists the health of the community would be more securely safeguarded from the possible ill effects of ingested dyestuffs. Under the present system it is apparently no one's business to detect the presence of harmful colours in food other than those actually prohibited, for obviously such work does not come within the scope of the Public Analyst. My last point is concerning the labelling of food containing added colouring matter. It has already been seen that colours are very frequently added to conceal inferior quality, or to simulate a valuable ingredient which is not actually present in the food. Therefore, in my opinion, the presence of added colouring matter should definitely be declared to the purchaser either by a label attached to the article or by a notice displayed in the shop. Such a declaration would help to counteract unfair competition. It is true that the Departmental Committee reported that “If a list of permitted colours is prepared in the way we have suggested, we do not think that, as far as health considerations are concerned, a declaration of their use need be required.” It is obvious that the Committee made that recommendation from health reasons alone and did not take into account cases where colour was added to conceal inferior quality. The food laws of this country lag far behind those of some others, and the tightening up of legislation in this respect is overdue. It is interesting to note that the following countries make the declaration of added colours to some or all types of food compulsory: The United States of America, Canada, New Zealand, Australia, Germany, Italy and France. Argentina takes a bold stand and prohibits absolutely the use of artificial colours in food, only harmless natural colours in certain instances are allowed. In America a food is not covered by a declaration of the addition of colouring if it is added to make the food appear of better quality or of greater value than it is. Also in America the labels of compound food such as confectionery must have a list of the quantities of the separate ingredients, exemption being allowed where there is of necessity insufficient space on the label to accommodate all the statements and information required. Unpacked confectionery, owing to the difficulty of labelling satisfactorily, is exempt. It has been remarked that a certain proposed label for use in America looked like a newspaper, and even the Readers' Digest could not condense it! Still, I feel sure that the intelligent purchaser would far rather have too much information, if that is possible, regarding the quality of the food he eats rather than too little, and those who, owing to lack of knowledge, are less discriminating in their choice of food, need to be protected. In conclusion, then, in my view, there is no objection to the artificial colouring of food provided that the colouring agent employed has no adverse effect upon the human organism, that it is not added to imply superior quality or to otherwise deceive, and that its presence, where practicable, is declared to the purchaser.