World Wide Chemistry ^ P ^ ~ 2 ^ ^ systems of probable \ j g ^ ~ ^ -rjpy revolutionary effect in RjpSfS^ domestic television re1^^^^^^ ceivers, and doubtless Jgl5y5B=|[ a p p l i c a b l e in o t h e r ^^^^"^ optical work, were described at a meeting of the Television Society in London on M a y 29. T h e new systems evolved in the Optical Development D e p a r t m e n t of the I CI Plastics D i v i sion, Welwyn, will render obsolete the present-day small curved screen which is inconvenient and unsatisfactory in m a n y ways. In its place will be a large flat screen of about 1G b y 13 inches providing a well-lit picture of great clarity to several people anywhere in a laj-ge room. To obtain larger pictures an optical system with large light-gathering power was necessary. Such a system, consisting of a concave mirror and corrector plate of complex shape and nonspherical surface, has been used for some years in astronomical work. The prohibitive cost of glass a n d highly skilled grinding has been eliminated by the use of t r a n s p a r e n t plastics of t h e T r a n s p e x type. T h e extreme accuracy required has been obtained by building up on lens surfaces a skin of the same material until perfect reproduction of the mold is formed. This unique process, known as surface finishing, has opened t h e w a y to widespread use of such systems, and their mass production a t a very moderate price, for use in television receivers and other optical instruments. David Starkie of the I CI staff, who read the paper before t h e Television Society, showed some interesting models or p r o t o types both for home, a n d cinema use, the latter giving pictures u p to 25 feet in diameter with 1,000-line definition. T h e s e screens, still in the experimental stage, are covered with tiny plastic lenses so m i n u t e t h a t there are 40,000 per square inch. Mass production of plastic optical systems by t h e surface finishing process will begin before the end of 1947, and be in full swing by t h e middle of 194S in a specially designed factory in the London area. Some of the new t r a n s p a r e n t plastics have physical properties eminently suitable for optical work, such as lightness, toughness (resistant to severe mechanical and thermal shocks), a n d high light t r a n s mission. When properly designed and mounted they can well replace glass—particularly Transpex 1 and 2 as m a d e by Improved methods to secure higher softening point, increased craze resistance, elimination of strain, and greatly im1826
proved optical homogeneity. Strain is largely eliminated by special methodsus-ed in the surface finishing process. T h e basic idea of this process -was t o m a k e a preform plastic optical coniponent as accurately as possible by some knov^n method and build up on its surface attain skin of the same material inside a n optically worked mold until its surfaces ma.de optical contact a t every p o i n t with t r i e mold. After stripping, t h e component would be ready for immediate use, care being taken to avoid any pressure in i t s production. Straight polymerization of the plastic in an optically worked mold w a s used for m a k i n g the preforms. Plastics of the Transpex type reach their fina.1 solid state via a liquid or monomeric state, with the aid of a suitable catalyst. light, i n stead of heat polymerization w a s p r e ferred, and much time was spent Ln seeking suitable photocatalysts a n d optimarn conditions. T h e r e is considerable c o n t r a c tion in volume in the liquid/solid transition with t h e most desirable optical plastics, b u t this can be reduced to some e x tent by partial polymerization of the monomer before filling the mold, and careful attention to viscosity and flow of "the l i q uid going into the mold. F u r t h e r details in the making of t r i e preform were given, including the casting of a very thin film of polymer on its surfa.ee so t h a t it is a perfectly accurate rc;plica of the mold interior. If mirrors are being m a d e a reflecting layer of a l u m i n u m is d e posited on t h e m by evaporation in. vacu.o. Glass molds are used. Special m e t h o d s have been devised for m a k i n g asphes-ic molds, requiring a good deal of skill a n d various mechanical devices. The* curves are machined to templates cut a.s accurately as possible, then finished by hand I-LSing flexible laps. Optical a n d mecnanical tests are applied at different stages, I n mass production in the new factory a large n u m b e r of molds will be used, traveling t h r o u g h t h e various stages of the process on a mechanical conveyor. Dr. Starkie pointed out t h a t the new surface-finishing process is likely to be of g r e a t v a k e in t h e general field of applied optics. Siii.ce it a l lows complicated aspheric components t o be m a d e a t a reasonable cost it is sure to affect the whole future of optical design. General
Refractories,
Ltd.
A t the a n n u a l meeting a t Sheffield it was reported t h a t the complete mechanization scheme a t the H i r w a u n works in South Wales had been completed early in 1946, and new plant erected a t the'works of C H EMIC
AL
a subsidiary, H . Foster & Co., Ltd., for p r o d u c t i o n of carbon blocks for blast furnace industry, w i t h further extensions p r o vided for increased production of magnesite and chrome magnesite bricks. A new l a b o r a t o r y is being built at W o r k s o p for considerable extension of research. In regard to s t a n d a r d i z a t i o n of size a n d shape of refractories, t h e chairman t h o u g h t t h a t m u c h could be done to eliminate a large percentage of t h e complicated a n d wholly unnecessary v a r i a t i o n s a t p r e s e n t dem a n d e d b y customers, with consequent saving in mold charges a n d time. Industrial
Gases
Industry
At the recent meeting of the British Oxgyen Co. the c h a i r m a n said that sales of gases d u r i n g 1946 were m a i n t a i n e d a t j , high level. Volume of o u t p u t last year was more t h a n two a n d one-half times t h a t of prewar. T h e r e is every indication of furt h e r expansion. M o s t of the gas-prodacing p l a n t s h a v e been reconditioned after heavy war service, a n d are ready t o meet all d e m a n d s . T h e company h a s a comprehensive d e v e l o p m e n t p r o g r a m for home a n d overseas. N e w research laboratories h a v e been engaged on work which it is believed will in n o small measure contribu t e to developments in the low-temperat u r e field a n d in t h a t of heavy chemicals, a n d the c o m p a n y is also cooperating in research involved in t h e use of low-purity oxygen in t h e coal, steel, oil, a n d chemical industries. G o o d progress w a s also reported from t h e branches in Australia, S o u t h Africa, India, t h e Middle a n d F a r E a s t , a n d N o r w a y . N e t profits for 1946 after allowing for depreciation, income t a x , a n d excess profits tax were £6S9,000. Linseed
Cultivation
A t t e m p t s are being m a d e to extend linseed cultivation. I t can be successfully grown t h r o u g h o u t t h e U n i t e d Kingdom, a n d h a s t h e further advantage t h a t it can be sown later t h a n beans, peas, or tares, a n d is little d a m a g e d by wireworms or r a b b i t s . British farmers are being advised t o replace t h e lost bean crops w i t h linseed which, after extraction of the oil for industrial purposes, provides a valuable source of protein feed for farm stock. Yields here average 10 to 12 cwt. p e r acre, t h o u g h u p t o 20 cwt. h a v e been obtained, from a b o u t 2 cwt. of seed per acre drilled or b r o a d c a s t . T h e residual cake after oil removal contains a b o u t 3 0 % protein a n d possibly u p to 9 % oil. Rayon C h e a p e r r a y o n fabrics, in shops, m a y shortly follow t h e M a y 1 a n n o u n c e m e n t of R a y o n Producers C o m m i t t e e t h a t t h e prices of a c e t a t e c u p r a m m o n i u m a n d viscose rayon y a r n , except crepe y a r n , are to b e reduced for all home trade deliveries on a n d after M a y 2 2 . T h i s is a result of repeal of excise d u t y o n rayon in b u d g e t proposals. Proposals t o reduce H a r b e n ' s (viscose silk makers) capital from £621,000 to AND
E N G I N E E R I N G
NEWS
caustic soda
soda ash
They're still in short supply, but I n o r d e r to incrc ase p r o d u c t i o n of C a u s t i c Soda, Soda Ash, a n d o t h e r basic c h e m i c a l s , Wyandotte Chemicals C o r p o r a t i o n h a s p l a n s completed, and i n s o m e cases e q u i p m e n t p l a c e d , to p t u n p e a c h d a y — a s i d e from b r i n e —15,000,000 m o r e g a l l o n s of w a t e r . . . to q u a r r y a n d m i n e 120,000 m o r e t o n s of l i m e s t o n e and coal a y e a r . . . a n d t o increase m a t e r i a l - h a n d l i n g e q u i p m e n t t o p u t 131,396.000 m o r e p o u n d s p e r d a y of r a w m a t e r i a l a n d processing fluids i n t o m a n u f a c t u r i n g operatLons. B u t t h i s is oii-ly p a r t o f t h e j o b t o b e d o n e before the ire c a n b e any i n c r e a s e d
VTYANDOTTE WVANDOTTE,
CHEMICALS
MICHIGAN
•
OFFICES
•
·
·
p r o d u c t i o n of C a u s t i c S o d a a n d S o d a A s h . E n o r m o u s castings m u s t b e c o m p l e t e d for new l i m e - k i l n s . O t h e r e q u i p m e n t , i n c l u d i n g a 310-ton, 15-story d i s t i l l e r , h e a v y c a r b o n a tors a n d a b s o r b e r s , m u s t b e " t a i l o r - m a d e " and p l a c e d i n t o o p e r a t i o n . I n spite of c r i t i c a l s h o r t a g e s of steel, building materials and heavy machinery, W y a n d o t t e is m a k i n g p r o g r e s s o n its t w e n t y five m i l l i o n d o l l a r p l a n t e x p a n s i o n p r o g r a m . M e a n w h i l e , w e a r e a l l o c a t i n g t h e availaide s u p p l y of C a u s t i c S o d a , S o d a A s h a n d other essential chemicals with t h e utmost fairness t o p r e s e n t W y a n d o t t e c u s t o m e r s .
CORPORATION IN P R I N C I P A L
CITIES
Soda Ash • Caustic Soda • Bicarbonate of Soda • Calcium C a r b o n a t e • C a l c i u m Chloride • Chlorine H y d r o g e n • Sodium Zincates • Aromatic; Intermediates • Dry I c e • O t h e r Organic and Inorganic Chemicals
V O L U M E
2
NO.
2 5
JUNE
2 3, 1 9 4 7
1827
W O R L D
W I D E
£475,000 will he considered by shareholders Muy 22, together with plans for modernization and expansion requiring at least £623,000 over a pr-riod to January 1051. T h e Uriti.-h Industries Fair, London ami Birmingham, opened M a y 5. At Birmingham there are 1,048 exhibitors (.132 nioro than lUo'P. Examples
