D E C E M B E R 20, 1935 tissues of cow pea, found t h a t it is present mainly in the leaf blades, and Giroud, working with several species, found a parallelism between t h e distribution of ascorbic acid and that of chlorophyll. Effect of Heavy W a t e r o n P l a n t Growth Contrary to earlier expectations, heavy water has not shown either highly stimulative or toxic properties in its effect on plants. Brun and Tronstad germinated peas in it up to concentrations of 40 per cent D 2 0 , and found no stimulative effects
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a t low concentrations. Plantefol a n d Champetier obtained optimum elongation of pollen tubes in 57 per cent D 2 0 . Curry, P r a t t , and Trelease reported no effect of dilute heavy water (0.46 per cent) on t h e growth of Aspergillus, on the germination of conidia of Erysiphe, on t h e growth of wheat roots, and on 0 2 consumption of wheat seedlings. Algal cells in contact with 97.0 per cent D2G for 15 hours were not permanently injured. In 99.9 per cent D 2 G, however, the rate of photosynthesis was reduced to 0.4 t h a t in ordinarv H20.
Developments in E c o n o m i c Entomology Synthetic Organic C o m p o u n d in Codling M o t h Control HENOTHIAZINE, a compound prepared P by fusing sulfur with diphenylamine, was mentioned last year for its remarkable toxicity to mosquito larvae. Since then it has shown promise for killing young codling moth larvae, when sprayed on apple trees. Some laboratory and field tests have given promising results but further tests are needed. These studies are being made in order to find a substitute for lead arsenate, which still remains the most generally used material. Blowfly M a g g o t s S t i m u l a t e H e a l i n g of Wounds One of the objects in the work with blowfly maggots, which are being used extensively by surgeons in the treatment of infected bones or wounds, has been to determine how the maggots produce their remarkable healing effects. In addition to removing diseased tissues it has been found that the maggots excrete certain substances into the wound and that one of these, allantoin, stimulates healing. Allantoin is available commercially and is now being used by doctors with gratifying results. Another substance excreted by the maggots has been found, though not vet identified, which in laboratory tests killed certain disease-causing bacteria in 5 to 15 minutes without injuring human tissues. D i s e a s e of H o r s e s C a r r i e d by Mosquitoes Equine encephalomyelitis, a fatal disease of horses, has been found to be carried by the dreaded yellow fever mosquito Aedes aegypti. This adds one more to the long list of diseases transmitted by insects and related forms. Wireworm
C o n t r o l by N o n - C u l t i v a tion of Land
Non-cultivation of land for one year has aided materially in reducing sandy land wireworm infestations in South Carolina. Chemical Baits as Insect Attractants Reinvestigation of chemical baits for attracting the Japanese beetle has shown that the combination of geraniol and eugenol is the most attractive. It was found possible to use a cheaper grade of geraniol. Rose geranium oil, eugenol, and tansy oil are definitely attractive to the Asiatic garden beetle (Auloserica castanea arrow) and may be tried in combination with light traps which are also attractive. This beetle has now spread westward to areas near Philadelphia, Pa. An interesting development in trapping the Japanese beetle is t h a t traps painted green and white are superior to those painted with other colors.
Other
S y n t h e t i c s Give P r o m i s e C o n t a c t Insecticides
as
Various thiocyanates continue to give promising results, not only acting as effective contact insecticides against various t y p e s of insects, including t h e highly resistant mealy bugs and some scale insects, but also against red spider mites, severe pests of many types of plants. Some of these compounds have also exerted a remarkable ovicidal action against the eggs of mealy bugs. In studies on the physiological action of aliphatic thiocyanates on insects it was found that they inhibit the contraction rate of t h e insect heart. A greater dilation of the heart was caused, apparently owing to a n effect in increasing the tonus of certain muscles attached to the heart. Derris, Pyrethrum, and Nicotine M a n y new developments with these insecticides have occurred. Derris has shown considerable promise in t h e control of various insects and pests. T h e finely ground derris powder mixed with water and applied as a spray has given good control of t h e Mexican bean beetle. A similar spray has also been effective against the pea aphid. By adding sulfonated castor oil to this same derris powder spray it h a s given effective control of the red spider mite on cucumber and other plants. A dust of derris powder has given good control of the tobacco flea beetle, especially in seed beds where i t is a severe pest of the young tobacco plants. Derris powder sprays have shown some killing action against t h e Japanese beetle, but more especially a distinct repellent action is exerted. Plants sprayed with a derris powder spray have in this way been protected from the attack of this beetle. Rotenone and the other crystalline compounds present in derris are apparently not its only toxic constituents. It is probable t h a t the non-crystalline ingredients of derris, such as optically active deguelin, exert an effect. The optically active dehydrodeguelin has been shown to be more toxic than t h e optically inactive isomer. Several years ago rotenone was found in t h e devil's shoestring, Cracca virginiana, a weed growing widely in this country. A recent study of plants of this genus gathered from different parts of t h e United States has shown that those from Georgia, Texas, and Florida contain t h e highest content - a s much as 1.8 per cent rotenone —of insect-killing constituents. P y r e t h r u m has also received considerable attention. A method has been developed for the isolation of pyrethrin II, which is much more simple and less drastic than any previously used. A simpler method of analysis has also been developed. An interesting experiment illustrating the difference in action of pyrethrum and derris has been reported, using the cabbage worm. W o r m s fed
pyrethrum powder, embedded in gelatin films, were n o t affected, but those fed with derris were killed. Worms allowed to crawl over t h e film containing pyrethrum but not allowed to eat it were killed but those crawling over the derris film were unharmed. Derris acted as a stomach poison but not as a contact insecticide, whereas t h e toxic action of pyrethrum was primarily contact and not a stomach poison in this instance. Anahasine, a n alkaloid similar to nicotine in chemical and insecticidal properties, has been found in the leaves and roots of t h e t r e e tobacco, Nicotiana glauca, of the southwestern United States. Ana-asine w a s first prepared synthetically several years ago by chemists in the Department of Agriculture and was later found i n a Russian weed, Anabasis aphyila. New
Wetting a n d S p r e a d i n g A g e n t s d o m i n g i n t o Use Compounds of sulfated fatty alcohols or acids containing 10 to IS carbon atoms, as well a s sulfated phenyl compounds, are coming into u s e as wetting and spreading agents a n d appear t o offer considerable promise a s substitutes for soaps and similar a g e n t s . T h e main advantage of these new compounds, in addition to their good wetting powers a t low concentrations, is their compatibility with many insecticides in dilute acid or alkali solution or in hard waters. Some are also effective as emulsifiers. Studies
on
t h e "Blood'" of
Insects
Physiologists specializing on insects have found t h a t the number of "blood" cells in the hemolymph of insects varies greatly, being as low as 2000 in some species a n d a s high as 180,000 cells per cu. nun. in others. The number of "blood" cells varies also in t h e same species with the growth, condition, and sex of the insect. Female insects a p p e a r to have a larger number of cells than males.
Advances in Physics H E N R Y A. BARTON, A m e r i c a n I n s t i t u t e of P h y s i c s , 11 E a s t 3 8 t h S t . , N e w Y o r k , N. Y. A t o m i c Nuclei FOR several years and until very recently, t h e forefront of physics was occupied by those whose efforts were devoted t o the formulation of theories describing the many important atomic phenomena discovered since 1900 and before. Q u a n t u m mechanics has now reached a high state of development a n d has proved i t s great superiority over previous theories which attempted to d e scribe the phenomena of atomic a n d molecular spectra, electricity in metals, the interaction of radiations with m a t t e r , etc. T h e theories have also had great success in describing subatomic phenomena, such as the existence of a positive electron, interaction of particles, a n d radiations with atomic nuclei, radioactivity, e t c . I t has been possible to set u p hypotheses concerning intranuclear structure. I t is now generally supposed that atomic nuclei are composed of neutrons a n d protons and laws of interaction between them have been formulated. I t m a y b e said that t h e o r y has gone ahead of experiment in the nuclear field more vigorously t h a n was true for t h e rest of the atom. For the past two or three years extraordinary progress h a s been made in experimental nuclear research and this now absorbs the interest
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of physicists. T h e work reviewed in t h e s e columns last year on nuclear transformations has been continued. Literally hundreds of nuclear ' ' r e a c t i o n s " are now known, in the course of which the nuclei of elements are changed to those of o t h e r elements or other isotopes of t h e s a m e element. These changes m a y be caused by t h e incidence of alpha-particles, protons, deuterons, o r neutrons (and possibly other rays) a n d give rise in t u r n to rays of all these types. Artificial R a d i o a c t i v i t y Some of t h e product nuclei are isotopes not before found occurring in n a t u r e . There are cases in which the same product can be formed in more than one w a y . M a n y of t h e new isotopes formed are unstable and shortly break down into stable known elements by t h e emission of an electron or a positron. This is t h e phenomenon of "artificial" or " i n d u c e d " radioactivity. Attempts are being made to increase the "yield" of artificial radioactivity to t h e point of competition with naturally occurring radium and its products. It appears likely t h a t the effort will be successful. It is necessary to select an artificial radio element which decays slowly enough for practical purposes (halflife a matter of hours r a t h e r than minutes or less) and yet not so slowly t h a t its radiations are too weak. It must also be one which can be produced relatively easily by a nuclear reaction. T h e most promising k n o w n reaction is t h a t between bombarding deuterons of several million volts energy a n d sodium ( D 2 + Na" > - H l + nNa 2 4 ). The product radiates electrons and decays with a halflife of 15.5 hours ( N a " >• e + 2 2Mg ). Radio-sodium is also produced by o t h e r reactions which involve neutrons—e. g.: nNa" + oni I , M R " + 0n» „AI» + on»
>. „ N a M > ,Hi + „Na24 >- 2 H e 4 + nNa*«
These reactions a n d t h e fact t h a t they are known illustrate the progress made in the field in a very short t i m e . I t has been possible to verify the Einstein law of the equivalence of mass a n d energy (E = mc 2 ). Nuclear reactions use t h e energy of motion of bombarding particles and of mass lost during t h e reactions. T h e total mass a n d energy m u s t be equal for each member of the reaction equation. Certain reactions were observed which seemed not only to d e p a r t from this law of conservation b u t to result in an increase of energy-plus-mass. These have led t o a slight revision of isotopic weights, since confirmed b y Aston with an improved mass spectrograph. Neutrons ordinarily penetrate m a t t e r much more readily t h a n any other particles or rays of comparable energy. T h e y are absorbed more by layers of paraffin, water, or other hydrogen-containing m a t e rials than b y lead. This phenomenon has been explained through the fact t h a t neutrons make a p p a r e n t l y elastic collisions with hydrogen nuclei and give u p a large part of their energy a t each encounter. It has been shown t h a t neutrons may b a t a r o u n d in paraffin until t h e y come into t h e r m a l equilibrium with t h e molecules. N e u t r o n s , so slowed down, no longer pass readily through m a t t e r , b u t are absorbed, probably by being c a p tured into t h e nuclei present. T h e power of absorbing slow neutrons varies m a r k edly among t h e elements, being so great in the case of c a d m i u m t h a t this element can be used as a shield for slow neutron rays.
AND
ENGINEERING
CHEMISTRY
It i s significant t h a t the Nobel prizes for physics a n d chemistry for 1935 were both awarded for work in these fields. The discovery of t h e neutron was credited to J a m e s Chadwick, winner of t h e physics prize, and t h a t of induced radioactivity to Frederick Joliot a n d his wife, Irene JoliotCurie, winners of t h e chemistry prize. Cosmic Rays Cosmic rays have been investigated as actively in 1935 a s in 1934, t h r o u g h worldwide surveys and pilot balloon ascensions using self-recording instruments, and recently during t h e stratosphere flight of C a p t a i n s Anderson a n d S t e v e n s . M u c h new a n d precise work has also been done in laboratories with counters a n d with cloud chambers in magnetic fields. W h a t ever t h e primary cosmic r a y s m a y be, t h e latter instruments show t h a t they are accompanied by showers of positive and negative electrons. T h e formulation of dependable theories regarding t h e n a t u r e
VOL. 13, N O . 2 4
a n d source of t h e rays is awaiting t h e stepby-step accumulation of accurate data a n d t h e separation of t h e numerous effects from one a n o t h e r . Atomic Spectra Among other fields m a n y i m p o r t a n t researches have been carried o u t . An example is the extension b y P . W. Bridgm a n of his studies of m a t t e r u n d e r very high pressure. A n u m b e r of new phases have been produced with increased pressures plus mechanical shear. T w o forms of ice produced are s t a b l e enough t o remove from the pressure a p p a r a t u s and examine with x-rays by t h e powder method. A new comprehensive s u r v e y of atomic spectra is being m a d e by G. R . Harrison, using a machine which a u t o matically measures s p e c t r u m plates recording wave lengths to eight characteristic figures and also line intensities. T h e machine has a capacity of 600 lines an hour.
Thirtieth Anniversary o f Laminated Safety Glass Marked by General Use in A u t o m o b i l e s P a u l D. B o o n e , R o o m 4708, U. S . P a t e n t Office, W a s h i n g t o n , D. C . TISa bit h a z a r d o u s to single o u t a defin i t e person a n d unequivocally s t a t e that h e invented some broad basic idea, for, a l t h o u g h the best records available may so indicate, there is nevertheless t h e possibility of plant use to a limited extent of which no records were' kept. B u t J o h n Crewe Wood, of Swindon, England, would seem t o be t h e person to whom t h e honor belongs of inventing laminated safety glass, for in December, 1905 a British p a t e n t , No. 9972, issued, entitled " I m provement i n Glass Screen Windows for M o t o r Cars." British p a t e n t s a t t h a t time gave t h e occupation of inventors a n d , s t r a n g e as it m a y seem, Wood w a s a solicitor o r lawyer. His description is both clear a n d interesting, reading in p a r t : To t h e above end my invention consists in providing two sheets of glass between which is fixed or cemented a sheet of film of any transparent adhesive substance or material with sufficient elasticity to prevent splintering of the parts; for example, I employ a sheet of celluloid between two sheets of glass o r a film of gelatine less brittle than glass a n d not liable to splinter.
I
Canadian balsam a n d sodium silicate were mentioned a s cements or adhesives. The non-splintering a n d greater strength characteristics of laminated glass have decreased the h a z a r d s of motoring, especially a t h i g h speed. Wood stressed t h i s in his original patent, b u t it took years before t h e public and manufacturers really appreciated i t s possibilities. In 1914 it began to achieve some commercial significance. T h e lenses in gas masks, goggles, a n d other e q u i p m e n t of t h e forces a t war were equipped w i t h safety glass. Then when automobiles, which prior t o 1919 were of t h e open design, changed to t h e closed t y p e the trend became inevitable in t h e interest of safety. There were m a n y problems which beset t h e manufacturers, such as discoloration of t h e layer between t h e glass, t h e tendency of the g l a s s to " l e t - g o " t h e plastic, and t h e cost of manufacture. T h e development of laminated glass can be followed by consulting t h e patents issued b y the U. S. P a t e n t Office, under t h e designation "glass u n i t i n g . " In t h e years prior t o 1028 only 14 p a t e n t s h a d been issued and o f these 10 were g r a n t e d to private inventors. T h e n m a r k e d acceleration i n their issuance followed and t h e efforts of some of t h e well-equipped cor-
poration research laboratories became evident. In 1928 t o date, 154 p a t e n t s , all but 21 of which were assigned to corporations, were issued. It is beyond the scope of this article to enumerate t h e various contributions or t o appraise t h e m , but some of the more recent will be sketched in part. T h e laminae h a v e been united direct t o one a n o t h e r by polymers of vinylethinyl carbinol, ethyl ester of acrylic acid, condensation product of maleic acid, a n d 1,3glycols. I m p r o v e m e n t s have been m a d e in uniting t h e plastics to t h e glass a n d a m o n g t h e bonding agents boric acid, in conjunction with silicic acid, find uses. Oxycellulose a c e t a t e for uniting glass to ester plastics is suggested. One p a t e n t of interest in connection with the modern t r e n d of streamlines is t h a t for uniting or forming curved laminated glass. A sheet of galvanized iron is placed between glass sheets. When t h e glass is at t h e proper temperature, heat and pressure are applied t o bend t h e glass. The metal is then removed and t h e spaced glass is bonded with a plastic layer. Credit is due John C. Wood for his invention in 1905, but praise m u s t be given for its perfection to the chemists since 1921 who have made i t a real success, a n d t o the companies providing t h e m with e q u i p m e n t unknown t o Wood and Benedictus, t h e two pioneers.
Miniature Glass Plant M I N I A T U R E glass p l a n t has j u s t been completed in the laboratories of t h e Bausch & L o m b Optical Co., Rochester, N. Y., a t a cost of $8000, a n d will tour m a n y of t h e larger cities of t h e United States a n d be shown a t scientific g a t h e r ings, industrial conventions, a n d m u s e u m s . T h e model, which took a year a n d a half t o build, consists of a b a t t e r y of t h r e e glassmelting furnaces, raw material storage bins, mixers, a n n e a l i n g ovens, casting table, a n d cutting rooms in operation, with small electric t r u c k s , m a n n e d b y miniature operators, transferring t h e molten glass from t h e furnaces to t h e casting table, where it is automatically rolled into sheets a n d conveyed into t h e ovens. An a u t o m a t i c film balopticon, synchronized with the operations of t h e model, projects the s t o r y of each operation on a screen a t t h e t o p of t h e model while t h e operation is t a k i n g place.
A
