GLASS FOR ENGINEERING AND INDUSTRY LEON QUIGLEY 730 Fifth Avenur, New Ycrk,
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N.Y.
HATEVER the requirements of the vast rearmament Nowhere is the extension of properties more strikingly program, laboratory men and plant constructors can connected with expanding fields of use than in the case of count on the availability of durable, heat-resistant, the new Pyrex Vycor 96 per cent silica glass. Manufacturing metliods depart radically from conventional practice. At the chemical-resistant, low-expansion glass. Authorities irr this field report that even exceptional demands can he met. start a special glass of apparently normal characteristics is Soeakina for the Corning Glass Works, treated by a new and unique process E: C. Knllivan says: "Based on rein which practically all the constituents cent surveys, it now appears probable other than silicaare removed by leachthat we can meet every requirement ing in hot chemical solutions. Confor these specialized glasses in considerable time is required for this treatnection with the program of national ment although it varies with the form defense." and type of ware. Comparing conditions relative to After being washed, dried slowly, the first World War, the manufacand finally fired a t carefully controlled turers of low-expansion glasses are now high temperatures, the silica residue in much better position to respond to becomes a transparent vitreous glass unusual wartime requirements. The of simple chemical composition. Exfirst World War found the industry ceptional chemical stability, high softunprepared to supply even the doening point, and very low thermal exmestic demand for chemical apparapansion are outstanding properties. tus. So great had been the reliance Glassware hsving these properties upon Europe, particularly Germany, is ideal for manyoperations in the labnthat industrial chemistry in the United ratory. Reactions can be carried on States was but poorly developed. So with greater speed and accuracy. F e w too was the apparatus end of the fields are also opened to researchers business. Itesearchlaboratoriesrelied because 9G per cent silica glass (No. upon imports from abroad, particularly 790) has an upper service temperature from Jena. By the time the United limit appreciably above that of Pyrex States entered the n w , however, pracbrand chemical glass (No. 774). tical production, in quantity, of lowCertain limitations are necessarily expansion borosilicate glasses had been imposed in the mairufacture of this achieved a t Corning. Thusinstituted, glassware. special oversize molds are these laboratory glasses subsequently required to allow for the shrinkage have become wolf known under the which occurs in the leaching and firing trade name, Pyrex. processes. There are also definite reThe first World War Drovided an strictions in the matter of size, shape, imperative incentive for chemical enand wall thickness. Dimensional tolgineering development and led to the erances required are in general greater establishment of a permanent chemical than those common to usual glass pracindustry which was destined to lead tice. the x,orld. By the time the Uuited Production is now confined to a States became a participant, low-exsmall pilot plant which does not perpansion glasses were being made in mit the manufacture of an extensive quantity a t Corning. Thislaboratory line of laboratory ware. Increased ware had a lower expansion than the manufacturing facilities are contemforeign borosilicate glasses and was plated and when available are exuected only half as soluble in water. Adequate wall thickness in which it could be manufactured added to its mechanical strength. During the ensuing twenty years, productionof laboratory ware has been expanded and adapted to include fields of chemical engineering in which other materials have hitherto held sway. Many production improvements have been made and advanced standardization has been secured. FRACTlONATlNR TowEn, ~ I L TOF PYREX GLASS SECTIONS To A I$ElGEl' OF What is more, properties of these 20 FEET,9 INCHES, Is USEDTO Iteglasses have heen modified with resultcomn PRODUCTS IN SOLUTION AS A I
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INDUSTIIIAL AND ENGINEERING CHEMISTRY
SEPTEMBER, 1940
1177
Corning’s light bulb division is now meeting an increased demand. America, caught unprepared in the last war, learned from Germany the importance of a chemical industry. As a result, American chemical research, encouraged in an emergency, grew until it leads the world. Under the present preparedness program, there will undoubtedly be much study of materials to replace those which might. be cut off or which are rare and costly. This work will mean increased consumption of laboratory ware of the standard types as well as quantities of tubing and other fundamental forms for laboratory setups and pilotplant construction. Conservation of metals may lead to increased use of Pyrex glass piping, fittings, pumps, coils, fractionating columna, arid beat exchangers. In contrast to metal, Che obvious advantage of transparency will be gained, coupled with high stability arid the possihiiity of cleaning with live steam, bot water, or hot acid solutions. In many equipment designs, glass and stainless steel will be used conjointly. During the last war there was widespread use of large glass tubes in the manufacture of nitric acid. Since that time a complete line of standardized piping and fittings has been developed. Nitric acid will again be required in huge quantities for explosive manufacture. It is believed that existing equipment is entirely inadequate to handle the anticipated volume. I n this field much new construction may be required for which low-expansion glasses should be eminently satisfactory. During reeent years there has @n m& a i l d y e industrial w e of stainless steels containing relativ y large
be necessary to use something in material which would have the sa sistance. ~n many instancetrglass During the past ten or fifteen years glass has been used extensively in Germany during th eriod of its rearmam t as an Ersatz or substitute material or metals of all k i n d p
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PYIlEX BRAND LABoRAToRY APPARATUS,DEVELOPED DURINQ THE FIMTWORLD Wan, TO TAKE THE PLACE OP IMPORTS CVT OFF FROM ABROLD,M A K E S MODERN LABoaAToRY ItE8sARCH INDEPENDENT OP F ~ I ~ E I SOURCES QN OF SUPPLY: (Inscrtl TRE
SHOCK, AND IMMUNITY TO ATTACK FROM REAGENTS MAKE PYREX GLASSA VALUABLEMATERIAL FOE PIPELINES
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GANGRENE AND OTHER AILMENTS ARE TREATED WITH THE PYAEX GLASS BOOT,Warcn G W E “PA~EWE ~ VnscULAn EXERCISE” TO Artma LEGS
Although we d o not have the full story on the manifold new uses of glass which have been developed in Germany, there are verified reports of applications in many branches of industry where normally it would not be considered because of cost or fear of breakage. Such fields include breweries, food product industries, and household plumbing, in addition to the more rigorous services of the corrosive chemical industry. In addition to the use of Pyrcx glass piping, joints, fittings, and pumps in the manufacture of nitric acid and nitrates, i t is being utilized extensively in halogenation processes, particularly chlorination and bromination. Medical and hiological fields are also affected by the preparedness plans and will make increased demands on laboratory glass. The Medical Corps of the Army will require huge quantities of blood testing and storing equip ment, also culture tubes, serum bottles, I’etri dishes, centrifuge bottles, and diphtheria antitoxin jars. Now that amethod has been found for storing blood so that it can be carried to field hospitals without sufferingdamage, there is a sudden demand for apparatus required
1178
INDUSTRIAL AND ENGINEERING CHEMISTRY
to separate corpuscles centrifugally and for vessels in which to store and freeze serum. Aside from chemical and medical uses, the calls of war on various departments of the glass industry offer contrast. Naval expansion requires radio insulators, lantern lenses, and fibrous glass for hull insulation. Expansion in aviation will call for large quantities of signal lenses and lenses for airway and airport beacons. Here fibrous glass will again be used as insulation. Side effects offer contrast in the grim tragedy of mechanized slaughter. One direct war result in terms of America and glass is that of our newest Christmas tree ornaments. These are being produced in the United States, for the first time,
VOL. 32, NO. 9
on a large-scale, low-price basis. Making Christmas tree ornaments was always a cottage industry centered in Poland, Czecho-Slovakia, and Germany. When the traditional European supply was threatened, midway in 1939, Corning began to develop methods for blowing glass ornaments. 4 i m was to make a product equally attractive, stronger, more uniform, yet inexpensive. During the past year the problem has been solved and the Wellsboro Division of the Corning Glass Works is now making enough glass ornaments to supply the whole country if need be. From blood banks to Christmas tree ornaments! Great is the gamut of war and its effects.
OPTICAL GLASS GEORGE W. MOREY Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C. PTICAL glass is a key material in our preparedness. With increasing range of gunfire comes the necessity for increasing precision of control, for fire-control instruments of greater accuracy and in greater numbers. Firecontrol instruments are optical instruments of precision, and their performance depends on the glass in their optics-socalled optical glass. Optical glass differs from ordinary glass primarily in its high quality. It is one of the purest materials of manufacture, not only in the chemical sense, but in the high degree of homogeneity which is its outstanding characteristic. It must be uniform in composition throughout; there can be no local regions of inhomogeneity, called “striae”, to deviate the light from its prescribed path. Other requirements must also be met-freedom from opaque foreign material, or “stones”, freedom from bubbles, precisely controlled annealing, and a chemical composition determined to a fraction of a per cent by the values of refractive index and dispersion specified by the lens designer. All these requirements are to be met by a material which must be melted a t a temperature so high that many of the constituents are volatile, in pots composed of the same materials as, and hence soluble in, the glass. A chunk of optical glass represents the highest perfection of the glassmaker’s art; its manufacture is a n art in itself. When we entered the war in 1917, the United States faced a shortage of optical glass which threatened to cripple our preparations. Stocks of imported glass had been practically exhausted by the previous production of fire-control instruments for the Allies. Importation was impossible. The situation had been foreseen by several groups, who were experimenting with optical glass manufacture. Of these, the Bausch & Lomb Optical Company had made most progress, but its potential production was far less than the quantity essential for our needs. Some success also had been achieved by the Spencer Lens Company, Keuffel and Esser, and the National Bureau of Standards. It is noteworthy that, although both English and French firms had long been producers of optical glass, no information or assistance was obtainable from our allies. I n the emergency the Geophysical Laboratory of the Carnegie Institution of Washington was called upon because of its wealth of experience with silicate solutions, and when the War Industries Board was formed, the director of the labora-
tory, Arthur L. Day, was placed in charge of optical glass production. The unification of control and wholehearted cooperation of all concerned resulted in the speedy solution of the technical problems which limited production, and a t the close of the mar first-class optical glass was being produced in quantity more than sufficient to meet our needs. Today the situation is far less serious, even though only one of the optical glass plants has continued in production. This is the plant of the Bausch & Lomb Optical Company, the largest manufacturers of optical instruments. Their factory has been in continuous operation, they have carried on active research on optical glass for several years, and their production capacity is adequate to supply a large part of our needs. Other sources of supply can be called upon. The Pittsburgh Plate Glass Company, one of the firms which made optical glass in the past war, has been studying the problem for some time. The optical glass plant of the National Bureau of Standards, which was moved from Pittsburgh to Washington after the war, has been producing a small quantity of excellent glass for many years. Recently, the Corning Glass Works has become interested in the manufacture of some of the more difficult types of optical glass, and their product probably is superior to any previously manufactured. We thus have one large plant in active operation and other potential sources capable of immediate expansion. Moreover, the knowledge of compositions and methods which we had to obtain by experiment, by trial and error, in 1917 is now available. The information and processes obtained or devised by the scientific group from the Geophysical Laboratory with the collaboration of the several glass manufacturers were freely published and are a matter of public record. Men with training and experience are available. Stocks on hand of optical glass are large enough to serve in an emergency until our production can be increased. The glass industry is able and eager to do its part; cooperation from industry is assured. Cooperation also is necessary from government. As was found in 1917-18, unified control is necessary to ascertain the needs of all branches of the services, to find out how much of what is needed, when, and by whom, to assure adequate and uniform specifications and methods of test, and to integrate the production of this vital key material as part of our preparedness program.
