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lengths up to 4000 A. They can be worked up in transparent laquers for painting window panes in ex hibition rooms, museums, etc., where preserved arts are displayed. T h e slight yellow color of these ultraviolet absorbers is not objectionable, being used only in concentrations as low as 0.5%.
AND
INTERPRETS
• Can be applied at room tempera tures • Has acceptable aging properties • Shows satisfactory flexibility
and lasting
The preservation of old painted masterpieces presents a multitude of complicated problems, Professor Uytenbogaart found. Relining, the best known method, seldom in volves removal of the old canvas, but the picture as a whole is glued on new linen. Formerly this was achieved with rye flour, but nowa days a mixture of beeswax and resin -e.g., colophony or dammar— as well as synthetic resins is used. T h e drawback of such mixtures is that beeswax must be applied in a mol ten state, and the required tem perature of 65°—68° C. may be det rimental to the pigments. Another difficulty is that linen, impregnated with beeswax, disintegrates much sooner than canvas. This is prob ably attributable to the attack of acids formed by the oxidation of higher alcohols present in beeswax. T h e preservation of old paintings calls for a plastic which : • Is inert to linen, paint pigments, etc.
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^ ^ I G A R E T T E companies are not likely
34 A
II
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C—R[_ C—Ν—R—Ν—C—R J η
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O—CH 2 —CH—CH 2 Epoxy polymer
The old canvas is placed in position on the new linen, both are im pregnated with liquid epoxy resins, and the subsequent hardening is catalytically accelerated. Polymer chains have two epoxy groups as each end group and are responsible in the hardening reaction—bridges are formed between the chains, resulting in a three-dimensional net work. Such a structure is of high strength and resistance, but is rather stiff. Since in the restoration of paintings and other objects, good flexibility is of paramount im portance, the catalytic hardening must be terminated at the proper time in the process. For this reason, still another polymer, which lacks this tendency
These polyamides react, by virtue of their reactive amino groups, with epoxys and form plastics with ex cellent mechanical properties, high chemical resistance, and a fairly high flexibility, because the forma tion of bridges between the chains of the epoxy molecules is hindered by the polyamide chains. A 50-50 mixture of epoxy and polyamide has yielded the most favorable results. Chemistry has entered deeply into the domain of restoring and preserving valuable articles, and has already shown unprecedented possibilities. Only a few of these have been summarily described, and this is only the start of chemical penetration into a fallow field— in the coming years, important work can be accomplished through the cooperative efforts of art circles, historians, and chemists for the preservation of our treasures. T h e art-loving world and all posterity owes a lasting debt to Professor Uytcnbogaart and coworkers. He is laying groundwork for future endeavor which may restore our masterpieces of art forever. J.B.P.
Anthracite Tries a Comeback
Colorful Filters to come out with a green-tipped filter cigarette, but if you're in the business of counting or sizing con taminant particles in air, fuels, hydraulic fluids, or other industrial liquids, a green-colored filter may be just what the doctor ordered. Gclman Instrument Co. has de veloped a thin, microporous, plastic filter with a dark green color for use in microscopic particle count and size determinations. In such a de termination a known quantity of
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The most success has been achieved by the use of epoxy resins :
Preservation of Old Paintings
to form three-dimensional struc tures, is added to the epoxy. T h e polyesters and polyamides are ap propriate in this application:
liquid is filtered, and microscopic examination of the filter by cither reflected or transmitted light re veals both size and number of foreign particles. Previously white filter materials were used, but white or light colored particles didn't show u p . With the new green filter, both dark and light colored dirt particles are clearly contrasted against the green background, ac cording to Gelman. It would seem that not very many dirt particles are dark green colored.
INDUSTRIAL AND ENGINEERING CHEMISTRY
H a r d c o a l , down in the dumps, struggles to gain new uses —ore processing best immediate bet V N E of the major victims of the widespread post-war boom in nat ural gas and—most recently—elec tricity for space-heating in domestic and industrial buildings has been "hard coal." Anthracite production
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MHI INTRODUCES...
LITHIUM ALUMINUM TRI-t BUT0XY HYDRIDE W a s t e banks like this in the Pennsylvania anthracite a r e a a r e now becoming r a w material stockpiles f o r coal n e e d e d in new chemical a n d industrial applications
in Pennsylvania, where most of this type of coal is mined, dropped from 69 million tons in 1930 to 18 million tons in 1960. Many specialists feel the market may now have bottomed out, and research in several countries is trying to find new uses to help this valuable carbon resource fight its way back. Development of industrial markets for anthracite as a source of carbon rather than merely as a source of heat is essential to the success of such efforts. In O r e A g g l o m e r a t i o n
One possible area, described to a recent anthracite conference at The Pennsylvania State University, involves ore agglomeration. Anthracite fines are a preferred fluxing
agent for sintering and pelletizing iron ores prior to reduction. As availability of lump ores diminishes, sinters and pellets of taconite form an increasingly larger proportion of the blast-furnace feed. Use of these agglomerates trebled over the past 10 years, from 15 million tons in 1950 to something over 45 million tons last year. In the same period, consumption of anthracite fines for this use jumped from a mere 300,000 tons to some 2.5 million tons. Expected boosts in production of agglomerates should result in a capacity of some 60 million tons a year by 1963, according to Bethlehem Steel's R. A. Limons and H. M. Kraner. At this level, they believe the anthracite industry would be called upon to
N o w , fine chemical and pharm a c e u t i c a l m a n u f a c t u r e r s have an important tool that reduces acid chlorides to aldehydes . . . stereospecifically reduces steroid ketones to hydroxy derivatives. With Lithium Aluminum Tri-t Butoxy Hydride, the acid chloride reduction procedure is simple and safe . . . and can be carried out at room temperature using standard equipment. Yields are high, as illustrated below: Acid Chloride Solvent p-nitrobenzoyl . . . diglyme benzoyl THF benzoyl diglyme p-toluyl diglyme m-chlorobenzoyl . . diglyme o-chlorobenzoyl . . diglyme pivaloyl diglyme pivaloyl THF
Yield 80 65 73 61 63 20 44 60
MHI technical service engineers w i l l be glad to help you take f u l l advantage of this new hydride. As a start, why not write or call for a comprehensive new technical bulletin. Laboratory quantities of the new hydride are available now!
25 G Sample Free!* Larger quantities are available at reasonable cost. Contracts for annual requirements are being negotiated now at even more attractive prices. •Shipped Express Collect P I O N E E R S IN H Y D R I D E
CHEMISTRY
Metal Hydrides Incorporated Penn State's Philip L. W a l k e r , Jr., uses fluidized b e d a p p a r a t u s to make highly a c t i v a t e d c a r b o n from p o w d e r e d anthracite
502 CONGRESS STREET BEVERLY, MASSACHUSETTS Circle No. 23 on Readers' Service Card VOL. 53, NO. 3
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produce about 4 million tons of fines. Though the hard-coal industry suffers from overcapacity, the demand for fines already exceeds production for this grade of product. As a result, existing anthracite silt banks—containing about 10 million net tons—are fast being depleted to give make-up tonnage for the fines used in the agglomerates. Chief competitive products for this application include bituminous coal (cheaper, but gives weaker sinters), petroleum coke (also cheaper, but has too high a sulfur content), and coke breeze (inadequate supply of these coke screenings). Semi-an-
Editorial
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thracite—some 500 million net tons arc recoverable—may get into the field of ore agglomeration if treatment can be developed to lower its high ash content. And breaker slate, now a marginal material containing about 5 0 % fixed carbon, would require crushing and benefication before it could become practicable. Electrodes for Aluminum Pots
Commercial aluminum-reduction processes consume about a half pound of carbon electrode material per pound of metal produced. In 1960, this amounted to nearly 1.5
Comment
w,
HEN it comes to turning a dollars' profit, you can generally bet that any medium used by the rank and file of vendors to promote that profit is a valid and worthwhile medium. Such a medium is written advertising— none will refute its value in presenting salable items to a vast number of prospective customers. O u r particular bone to pick here is with the printed matter mailed to an ofttimes long list of receivers who may (1) consider direct purchase, (2) request more detailed information, (3) screen it for passing along to higher authority, or (4) consider it for publication and subsequent dissemination of its contents to an even larger number of prospects. This is the press release—or news release—or public relations news—or whatsits-o-gram—or whosits-flash. . . Call it what you will, it is still a written presentation of information about a product, article, service, process, etc., which you wish to be seen in an attractive and appealing light by large numbers of people. But neither flashiness, wordiness, nor large volume of material has a lasting—or even a fleeting—impact on the person who is interested only in the subject contained in the release. That person is concerned with things such as: What is it? What does it do and how does it work? What is it made of? How big is it? What are its uses, properties, fields of application, and advantages? How much does it cost? Where can I get it or more information on it? He is definitely not attracted by a large number of other nonrclated gadgets the company produces. He isn't the least interested in the name of the company's president or sales manager. He couldn't care less that the company was founded in 1836 and that they had moved to a bigger and better location across the lake last June. No busy executive has the time to wade through a lot of gobbledygook to find the subject of the release. No busy plant engineer has the patience to read four typed pages on every simple piece of new equipment. No busy editorial staff member has the inclination to re-read the same paragraph printed three times just so the matter on the page won't look lost and insignificant, particularly if his regular duties include evaluation of scores of releases daily. An old saw like "Any piece of slick paper with red on it goes in my wastebasket," or " I refuse to read any letter over one typewritten page" carries this very real connotation, whether half-truth or empty threat. But in the opinion of many—and most but not all of those arc on the receiving end of press releases—this is not a case of getting out of a thing how much you put into it, but what and how it is put in.
Will H. Shearon Jr 36 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
million tons of carbon for aluminum producers in the U. S. and Canada. Anthracite is frequently used now in pot lininqrs, says Aluminium Laboratories Limited's J. P. McGcer. He notes that calcination, which reduces the volume of the coal by 2 0 % and stabilizes it dimensionally, removes ash and volatiles at the same time and improves electrical properties. Since the carbon lining of an aluminum reduction cell carries current from the molten bed, heat generated in the lining constitutes a power loss. McGeer finds that, though resistivity varies with ash and volatiles content of the green coal, this variation is small enough to be compensated for by a change of 100° C. or less in calcination temperature. He says this means resistivity specifications can be targeted easily regardless of anthracite source. The aluminum industry prefers petroleum coke as electrode material. But ALL's E. A. Hollingshead finds that he can purify anthracite by chlorination so that it can be used for electrodes. Precalcining green coals and chlorinating them at 1400° C. reduces ash content to as low as 1%. This treatment lowers sulfur content moderately (to 0.5% or less, as compared with 2 % to 4 % for petroleum coke), and reduces metallic impurities deleterious to aluminum reduction (notably Fe, Si, and Ti) to levels comparable with those for petroleum cokes. Chlorine content exceeds 1% in the treated anthracite. This is basically "somewhat undesirable" for aluminum processes, but he feels it doesn't preclude use of the coke for this purpose. In general, Hollingshead finds the purity of chlorinated anthracite proportional to purity of the raw coal. Anthracite Adsorbents
Two coal researchers from Penn State believe anthracite is a promising raw material for making activated carbon. Using CO2 as an oxidizing gas, Masayuke Kawahata and P. L. Walker, Jr., open the fine pores in anthracite. This makes it compare favorably, in adsorption {Continued on page 39 A) Circle Nos. 109, 110 on Readers' Service Card-
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properties, with commercial car bons. With approximately 5 0 % burn-off at temperatures beween 800° and 900° C , activated an thracites show pore volume of about 0 . 5 % cc. per gram (five times the original figure), surface area of 1400 sq. meters per gram (nearly 1000 times the nitrogenadsorption surface area of untreated coal), and adsorptivc capacity of 0.7 gram CC14 per gram. They sec one possible drawback in a relatively high mineral con tent for anthracite coke. But with steam (rather than the CO2 they used for reaction simplicity) as an activating agent, they look for higher adsorptive capacity and lower min eral-matter content at less burn-off. They conclude that, if necessary, chlonnation could be carried out in conjunction with steam treat ment to solve this problem. D.G.W.
Silicone on Stone Ο Τ Ο Ν Έ parts of seven buildings on the Kansas State University campus have been given added weather re sistance by coating with a water solution of sodium methyl siliconate, but F. C. Lanning of K-State's chemistry department is now working on what may be his most unusual project. Recently he received, much to his surprise, two large pieces of rhyolite, a volcanic stone used throughout the Orient for Buddha statues. T h e samples came from a Japanese chemist at the Osaka Industrial Research Institute, along with a request for Professor Lanning to test the effectiveness of silicones as water repellents on this particular stone. Studies are under way, and it appears that one of the silicones will be effective on rhyolite. Outdoor weathering tests have indicated that coating stone struc tures with silicone water repellent can save the owners unnecessary expense in repairing freezing and thawing damage caused by water absorbed into the pores, in addition to cutting down wall leakage during rain storms. Silicones do not work well underground, however, be cause they are broken down by alkalies in the soil. J.H.O.
AUTOMATED Hydral-60
PINCH VALVE SYSTEMS Controlled circuitry for any operating requirements • The Massco-Grigsby Hydral-60 System consists of one or more pinch valves with a single automatically operated hydraulic pump.
• Valves may be coordinated and inter locked with other plant equipment to automatically control tank levels, rate of flow, etc.
• Hydraulic pump may be operated ated by electric motor or by air from normal plant supply system.
• Valves may be independently con trolled for normal or rapid closure.
• Valves may be the same or different size. • Valves in the system may be operated simultaneously or independently. • Control valve may be manual or sole noid. • Valves are self-supporting and may be operated in any position from horizontal to vertical.
• Valves may be held fully open, fully closed, or at intermediate positions. • Remote control to meet individual re quirements. • Controls may be included for auto matic emergency operation. β 3 " to 1 4 " I.D. sizes, with 50, 100, and 150 psi line pressure ratings. • Temperatures to 200° F.
Advantages of Massco-Grigsby Pinch Valves β Rubber, neoprene and special com pounded rubber sleeves for corrosive and abrasive pulps and liquids. • Patented " h i n g e d " sleeve. Recesses serve as "hinges during compression; reduce strain and permit tight closing.
• Split flanges and patented Flex Seal ends assure perfect seal. • Rugged, heavy duty construction for most severe service and long life. • Cannot leak or stick. • No working parts in contact with pulp or liquid; no packing glands.
• Unobstructed flow eliminates high friction loss and prevents contamination
WRITE FOR NEW CATALOG Tho Company that oaroa onough to giVo you tho boat!
MANUFACTURING
NO. 609
DIVISION
M I N E A N D SMELTER SUPPLY CO. Denver 16 3800 Race St.
New York 17 122 E. 42nd St.
Salt Lake City 1 121 W. 2nd S.
El Paso 1515 11th Ave.
Albuquerque 701 Haines N.W.
LICENSED MANUFACTURERS A N D SALES AGENTS in C a n a d a , A u s t r a l i a , S w e d e n , E n g l a n d , South A f r i c a Sales Agents in M e x i c o , Peru, C h i l e , P h i l i p p i n e Islands, J a p a n , N e w York C i t y ( f o r Continental Europe) a n d in p r i n c i p a l cities o f the U. S.
Circle No. 24 an Readers' Service Card VOL. 53, N O . 3
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