GLASS Important War Material A L E X A N D E R S I L V E R M A N , Department of Chemistry, The University of Pittsburgh, Pittsburgh, Pa.
Φ*ο»ι tUiê, acc044*tt o£ direct a*td ituUnect appJicatio+U o^ ψΙα44, Ut VOotlcL It/a* / / , includUuf tUo&e tn&ie c&tfunottltf, Utuuum. and tUo&e IB4A. pddUiciped, it 44. oiuÙMl tltat ate c&uld *uU uU*i without it: OfxticcU, cÂetfUcai, plate, êtnucttilal, fcl&i, {/OCMK, G4UL ULdSfOtuitieUf ftczUuMiHe. Ot U Ike. eye a+td tlte dJUeld ofi tke /tinted tyatceA. G A S S is an indispensable factor in the winning of World War I I . I t is the mouth, the ear, t h e eye, of t h e widely scattered Armed Forces. I t is their window, y e t it shields them. Of all the vibrations of radiated waves, t h e unaided eye can detect only those of wave lengths 4,000 to 8,000 A. units, the proportionate equivalent of one black key (flat) t o the entire piano keyboard. Glass devices record or detect all t h e other waves. The voice has limited volume and range. T h e t r a n s m i t t e r bulb sends inaudible waves a r o u n d t h e world, and radio bulbs receive t h e m and render t h e m audible. A n d i n their armored planes a n d ships a n d cars, m e n wage their battles behind " t r a n s p a r e n t steel". T h u s is mode r n war conducted. O p t i c a l Glass Prior t o World W a r I America imported m o s t of her optical glass from G e r m a n y . O u r i n d u s t r y was either affiliated with G e r m a n industry or almost entirely dependent upon it. We had imported p o tassium carbonate (pearl ash) from Germany, s o when w a r was declared we were caught short and did not even h a v e potash t o make optical glass, though other requisites—borax, lead oxide, b a r i u m compounds—were a b u n d a n t . Fortunately these experiences t a u g h t a valuable lesson. Instead of depending upon potassium compounds from t h e Stassfurt mines and G e r m a n y ' s b e e t s u g a r industry, we developed a n American potash industry utilizi n g our natural minerals, and fabricating w i t h electricity produced b y n a t u r a l water power. Also, t h e Geophysical L a b o r a t o r y of the Carnegie Institution, cooperating w i t h t h e optical industry, developed m e t h o d s for producing t h e desired glasses with t h a t efficiency which characterizes Americ a n enterprise. The ensuing y e a r s ensured success in t h e present conflict. When we entered t h i s war, we could produce all of t h e comm o n optical t y p e s a n d had an appreciable reserve of research records which h a s been precious. W i t h a joint committee on F i r e a n d Optics of t h e Army a n d N a v y , a n d with m e n of experience in government
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bureaus and in industry, it was only necess a r y to increase production sufficiently. T h i s was accomplished through competitive ambition in industry and through federal subsidization of a vast ultramodern optical glass plant in Parkersburg, W. Va. N o t only was optical glass made in conventional ways, b u t rapid fabrication resulted through rolling and casting by large-scale manufacturing methods in plate glass and pressed glass plants. F a c tories t h a t had never dreamed of making optical glass got yields so perfect t h a t the quality of product seemed incredible. And be it remembered t h a t except in plants subsidized b y and operated under governmental direction, the manufacturer h a d to conduct his own experiments and s u b m i t satisfactory samples before he could get a government order. This aspect of optical glass manufacture will some d a y bring to light a combination of patriotism, pluck, enterprise, a n d sacrifice on t h e p a r t of glass producers t h a t few of us
have even imagined. T h e r e were two ways of increasing optical glass production quickly: one, to convert existing factories in other glass fields to t h e painstaking production of optical m e t a l ; two, to s u b sidize a n d construct exclusive optical plants. T h e former came largely through risks t a k e n b y the manufacturers, m a n y of whom did not succeed, and suffered losses. T h e successful ones, with t h e expansion of our already-existing optical glass i n d u s t r y and completion of t h e government plant, have m o r e t h a n m e t our m i n i m a l requirements. What is this optical glass? An ordinary lens or a prism? Definitely not. W e have well outfitted trucks in all wrar zones for ophthalmic, optometric, a n d complete lens a n d o t h e r optical fabrication service. Also t h e r e is motion-picture equipment for instruction and e n t e r t a i n m e n t . I n America, besides the more common crowns and flints, m a n y special glasses h a v e come into being. T h e r e are t h e silica-free glasses like t h e zinc-cadmium-aluminum p h o s phates, a n d others, some of whose compositions h a v e not y e t been disclosed. These h a v e a n appreciably greater index of refraction a n d lower dispersion. T h e y have e x t e n d e d t h e field of wide angle p h o tography which h a s served aviation so well. Accuracy a n d definition are essential
Light bulbs that generate heat rays bake enamels on armored cars and trucks by radiation
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1999
i n plotting targets. Optical glass and optical instruments have given these. We need glass for telescopes and microscopes, for lighthouses, for binoculars, bomb and gun sights, range finders, periscopes, cameras, and projectors. This is colorless glass, transparent t o radiations which are visible to the unaided eye. We have "smoke" glasses, b u t w e also require colorless and colored glasses, transparent or opaque to special radiations. A few examples will illustrate these types. There are spectacle or goggle lenses that cut out ultraviolet, others that cut out infrared. In welding goggles there is a low transmission of white light with absorption of heat rays. R e d aviation goggles ensure better visibility through fog and haze. Certain dichroic glasses accentuate green or red objects, increasing definition. Polaroid goggles eliminate blinding glare. But optical principles carry farther. There are lenses and enclosing globes of various designs and sizes. These m a y m e e t the requirements of t h e U. S. Army or N a v y , or may be supplied according to British specifications. There are the colored glasses which are employed for flood-lighting and camouflage. The spectral transmission is fixed. R e d , green, and b l u e units of various types must possess definite t o t a l absorption limits and transm i t within certain limits a t fixed w a v e lengths. There is a variety of reds, greens, ;and blues depending on the use, or o n the government bureau which establishes the specification. Glasses are in use which absorb practically a l l visible radiations and transmit only ultraviolet; others absorb all visible light a n d transmit only infrared. X - r a y bulbs transmit the shortest waves. I n bulbs used for sunbathing, visible ultraviolet a n d infrared go through the glass, while i n h e a t lamps t h e visible and infrar e d pass- T h e bulbs used i n radio transmission, in wireless telephony, and in radar are included i n t h e special types. Some glasses are clear ; others are etched or sand-blasted. I n t h e optical lens field, etching has played a n important role. Fluorides and hydrofluoric acid have been applied t o polished surfaces t o reduce reflection losses. A clear glass, untreated, reflects a b o u t 8 per cent of incident light from i t s t w o surfaces. Increase the number of surfaces, as in a composite lens system, a n d light losses m a y total 50 per cent or more. The production of molecular nonreflecting films on the surfaces of compound lens parts m a y almost double light transmission and result i n much greater speed in. photography.
Chemical Glassware Before World War I we made an alkaliresisting glass, and during t h e war a number of manufacturers of lamp chimneys and coffee percolators tried their heatresisting glasses for laboratory purposes. T h e y worked pretty well b u t did not equal
2000
A startling contribution to W o r l d War M is spun glass for insulation, holding heat in huts for the A r m e d Forces in the A r c t i c , and keeping men cool in armored cars in the tropics
the old Jena and Triuringian glasses that had been imported regularly prior to t h e war. Then came t h e American experiments with high borosilicate glasses, corrosion, thermal, and shock-resistant. These products largely eliminated foreign competition. Completely t o stop this, t h e Government discontinued duty-free i m portation privileges w h i c h had been granted to colleges and universities. For awhile selfish dealers capitalized on the profits of cheap foreign labor and tried t o compete with American manufacturers of laboratory glass. Quality won, and with few exceptions scientific America was independent of European markets long before World War II. We still imported specially constructed instruments, b u t these, too, are now made here. Scientific glassware is n o t limited to laboratory test tubes, beakers, and flasks. Special compositions permit the passing or absorption of certain rays s o that fermenation and other reactions m a y be accelerated or retarded a t will. T h e glasses m a y be colorless or colored. One red glass e n sures the stability" of vitamin C during assay. Green glasses absorb infrared. Clear glasses transmit ultraviolet; in fact, transmission in this region m a y range from the near ultraviolet of sunlight t o the shorter wave transmissions of very high silica glasses a n d transparent fused quartz. The thermal-shock resistance of the last-named glasses permits the arresting of high-temperature réactions b y sudden chilling, for it i s possible even to place these glasses on i c e and impinge an oxyacetylene flame o n the interior. High-silica and transparent fused quartz tubes arid bulbs are used in lamps for sterilizing the atmosphere of operating rooms, for tenderizing meat, and in coldstorage units to prevent spoilage.
CHEMICAL
The laboratory type of glass has extended its usefulness. Compositions which before the war entered the kitchen as oven doors and cooking ware are made into large cast cylinders for condenser columns in industry. Laboratory tubing has evolved into glass pipe for plumbing either with welded or coupled joints. Transparency ensures cleanliness, prevents contamination. T h e laboratory type of glass goes into pumps in chemical industry where metal would be attacked and constitutes parts of other mechanical devices. Among the last of our "independence" products were microscope slides and cover glasses. The latter tissue films are now successfully blown in huge bubbles, gaged a n d trimmed into small disks in several American factories. And they m e e t exacting specifications. T o prevent the loss of entire units, many interlocking and replaceable parts have b e e n designed for chemical apparatus. T h e s e effect economy and afford variety i n equipment design and assembly. Glass tubing furnishes the thermometer t o record body temperatures as well as those surrounding ground, marine, and air forces. A new annealing process greatly reduces the time required for making accurate thermometers. Thermometric control of plant and process ensures uniformi t y and production constancy. T h e tube and glass plunger make u p the hypodermic syringe, and glass ampoules and sealed tube vials store serums and antitoxins for the prevention and treatm e n t of disease. Glass ring and contact gages, replacing and conserving metal, ensure dimensional accuracy in cast and machined parte. T h e y do not dent if dropped. If injured they are replaced as any imperfect gage, metal or glass, should be.
AND
ENGINEERING
NEWS
Plate and Window Glass This branch of glass manufacture produces the microscope and lantern-slide glasses as one extreme and t h e unbelievably thick, clear, transparent bomber noses and peep holes as the other extreme. I t w a s considered a great achievement when 3-inch and greater thicknesses of laminated polished plate clearly transmitted images without distortion, b u t w h e n curved laminations proved equally accurate, that was a real accomplishment. Ability t o withstand great differences in external a n d internal pressure permits atmospheric pressure control within planes a t high altitudes, yet ensures visibility. T h e many applications of standard varieties of plate and window glass, tempered or laminated, i n trucks and armored cars are too well known t o require elaboration. T h e rolling and casting of special plate for subsequent cutting into optical blanks h a v e been mentioned. Plate and window glass have contributed their part t o factory construction and i n the various housing projects. Small polished plate mirrors, specially designed, now constitute a part of emergency kits for t h e Armed Forces. They ensure the sighting and signaling of rescue planes. Transparent mirrors permit unseen observers clearly t o view and plan war maneuvers. Before t h e war France produced plate glass heaters with continuous aluminum patterns fused into the glass surfaces. T h e s e carried electric current and became h o t . T h e vertical units are now made i n America t o serve as space heaters and conserve metal which would ordinarily be required for the manufacture of stoves and furnaces.
Structural Glass Hollow tile was in use before the war. I t h a s permitted metal conservation in factory and general construction. T h e greater transmission of light b y the structural material has conserved electricity. T h e insulation against heat loss has made fuel economy possible. A n ideal material for air-conditioned units, hollow glass tile has permitted perfect atmospheric control where necessary. T h e hollow tiles, while transmitting light, can s o diffuse i t a s completely t o mask factory operations t o outsiders when secrecy is required. If transparency is wanted, some tiles now approximate the quality of polished plate.
Fiber Glass Though known as glass wool a century ago, this b a b y of t h e glass industry has probably m a d e t h e m o s t startling contributions of all glass t o World War I I . I t i s glass wool insulation that keeps men cool in armored cars in the tropics; i t is spun glass t h a t keeps the heat in, in huts and transportation units i n t h e Arctic.
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in scrum production, hypo dermic syringes, ampoules, and scaled tube vials o f glass safely store antitoxins, scrums, vaccines
Glass cloth hangs as fire curtains or partitions in war vessels. In t h e garments and planes of aviators the wool keeps them warm a t great altitudes. Properly metallized i t may b e heated electrically. As a casing or flexible tube, or as s h e e t s , glass cloth is a n electrical insulator for metals, or a separator in storage batteries. B e tween glass plates, or imbedded i n transparent plastic, it is a heat-insulating lightdiffuser. The lightest batting weighs only half a pound per cubic foot. Substituted for old-fashioned insulation, this quality of glass wool reduces the weight of a battleship by almost 500 tons and permits t h e carrying of more men and cargo. Glass fibers filter blood plasma on t h e battlefield, and glass sutures stitch t h e wounds. Glass-cloth tarpaulins, waterproofed with synthetic resins, protect men and machines from snow, rain, mist, dampness. Their rigidity, when specially constructed, ensures accuracy i n maps and firing charts.
Foam Glass Glass which resembles a frozen, froth, and is largely air in the glass bubbles of the solid froth, m a y be produced in various shapes, large and small. Its air content makes i t a heat insulator, and 5t possesses the advantage over glass wool that it does not sag or settle; also it is vermin- and rodent-proof. Foam glass floats. I t is used in life belts, buoys, and life rafts. At home it now constitutes t h e floats in toilet tanks, and is releasing copper and rubber, formerly used in making floats, for -war uses.
Illuminating Were We have long been able t o turn night into day, and it is our good fortune that here w e lead the world. T h e 24-hour operation of war plants throughout the
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length and breadth of America is victory insurance. Of bulbs we have a "thousand and one" varieties from t h e "black light" for fluorescent control panels, t o white; from the flashlight bulb t o t h e sealed-in headlight and beyond to the more recent high-power units. New light bulbs, that generate heat rays, bake enamels and lacquers on armored cars, trucks, and other war products, by radiation. Of tubes we best know the fluorescent types, s o efficient in factory lighting. H o w many of us know t h e water-cooled highsilica thousand-watt mercury s'cigaret" lamp, s o named from i t s shape and size; the larger incandescent mercury arcs which produce the billion candle power beams for flooding the skies to locate enemy aircraft? Less powerful floodlights, with their color filters, serve i n camouflage on land and sea. Sodium vapor lamps ensure safe night travel for war workers. Thermionic bulbs sort their products.
Bottles and Table Ware Bottles are so common that wë pay little attention to them. T h e war has changed some of their shapes and their weight, to conserve space and lighten cargoes. B u t there have been other changes. We require special shapes for penicillin culture. We require special colors and compositions t o protect bottle contents. Perhaps the bottle stores important medicinals. Perhaps, under its sealed neck, lies the desiccated blood plasma. Or it may contain sterile distilled water to dilute the plasma before transfusions. Contamination might prove fatal. Special glasses are required for hand grenades and for containers for war chemicals. Our laboratories and factories have produced what was wanted. Vacuum bottles and flasks store hot coffee for factory worker and warrior alike, and prevent spoilage of stored liquids i n our hospitals i n the tropics. And finally, there are the common tumblers, pitchers, carafes in the mess halls. Many of these are tempered to harden the surface and make them shockresistant.
Conclusion World War II began with reverses. With the turn of the tide, forward progress has been steady. Glass in sheet and plate, in lens and prism, in fiber and foam, in lighting bulb and tube, bottle and beaker and flask, provides victory insurance. BASED on a u address delivered September 6, 1943 i n Pittsburgh, F a . , before t h e Division of Industrial and Engineering Chemistry of t h e AMERICAN
CHEMICAL
SOCIETT.
Contribution
N u m b e r 543 from the Department of Chemistry, University of Pittsburgh.
2001
