43 6 



NATURE 



[September 28, 191 1 



tion gives an accurate result to within about two parts in a 

 end. 



Dr. Lowry gave a valuable paper on the origin of general 

 ■ lf "l specific absorption, virtually an extension of the report 

 of the Commitee on Dynamic Isomerism, which is doing 

 work of extreme value in this difficult field. During the 

 pasl year attention has been directed to the study of general 

 '' orption, and attempts have been made to determine the 

 approximate positions of the inaccessible hands to which 

 this type of absorption curve appears to be due. The 

 method adopted depends on the fart that most of the 

 optical constants of a substance increase with great rapidity 

 when an absorption band is approached, and appear to tend 

 towards an infinite value in the case of a sharply defined 

 absorption-line. With carbon compounds the magnetic 

 rotatory disDersion has been found a convenient property to 

 discuss, and the measurements have been used to calculate 

 the position of the heads of the inaccessible bands by which 

 the- general absorption is produced. 



The chief conclusions drawn are that the optical pro- 

 perties of most saturated carbon compounds are determined 

 bv .111 absorption in the far ultra-violet. The dominant 

 absorption is brought nearer to the visible region by intro- 

 ducing an ethnoid linkage, as in ally] alcohol or a 

 oid nucleus, as in phenylethylcarbinol, but in none 

 of the simple compounds investigated does it fall within the 

 region usually photographed in the studv of absorption 

 spectra. 



Mr. J. E. Purvis described the ultra-violet absorption 

 spectra of the vapours of organic substances, as compared 

 with their absorption in solution and in thin films, and 

 discussed the results from a consideration of the move- 

 ments of the atoms of the molecules being influenced bv 

 their nature, weight, type, and orientation. The vapour 

 molecules have a greater freedom of movement and a con- 

 siderable number of bands are produced. In solution the 

 solvent acts partly as a constraint on the vibrations, partly 

 as a barrier to the number of encounters, and partly as an 

 absorbent of the radiant energy, so that the narrow 'absorp- 

 tion bands of the vapours are usually replaced by wide 

 diffuse bands. In thin films the movements of the" mole- 

 cules are further restricted ; the selective absorption is not 

 unlike that in solutions, but the bands are shifted more 

 towards the less refrangible regions. 



Dr. P. V. Bevan introduced the subject of absorption and 

 dispersion in metallic vapours. Following the work done 

 by R. YV. Wood in the case oi sodium, he has measured 

 the characterise lines ,,f other alkali m< tals. These ell 

 appear as absorption lines when while light is p 

 through the vapours of the metals; with increase of density 

 of the metal more lines come into view. They form a 

 series, getting closer together at the ultra-violet end of the 

 spectrum. The bearing of the phenomena of dispersion in 

 metallic vapours on the optical theorv was discussed par- 

 ticularly the views as to the nature of the atom and 

 the vibrating systems that give rise to spectrum lines. 

 Each line of the series is probably due to a special set of 

 atoms, and there are indications that the complexity of a 

 spectrum is not due to complexity of each individual" atom, 

 but to differences actually existent in the atom. There is 

 a good deal of evidence leading in the same direction. 



Rubidium and cesium vapours are i p tctically 



pure by heating the chlorides with lithium, owing to the 

 much greater temperature required for vaporising lithium 

 than for the other metal 



The concluding paper read bv Prof. Pope summarised 

 work done Jointly with Prof. YV. H. Perkin on optically 

 active substances which contain no asymmetric atom in the 

 molecule. The demonstration of the somewhat involved 

 conceptions employed was rendered intelligible by the use of 

 models, ill, authors have synthesised i-methylcyeZohexyli- 

 dene-4-acetic acid and resolved it into opticallj active com- 

 ponent ol brucine. It is proposed to distinguish 

 tins up- of asymmetry as " centroasymmetry. " The 

 of bromine and other substances on these acids was 

 described; it is remarkable that no evidence of any optical 

 inversion was obtained. It is noteworthy, further, "that the 

 long series of changes to which the centroasymmetric acids 

 were subjected yielded products, which did or did no 

 optical activity precisely in accordance with anticipations 

 based on the study of the solid models representing the miIi- 

 stanccs concerned. This is an important demonstration of 



2l87, VOT - 87] 



the fidelity with which constitutional formula- depii ' 

 cular configuration, and should not be overlooked 

 physicists. 



Prof. II. Euler, of Stockholm, opened the proceedings on 

 the Monday with a brief paper on the velocity of form., 

 of enzyme systems. The results described, though o 

 preliminary character, were significant as showing how the 

 amount of a particular enzyme in an organism can be 

 caused to increase by cultivating the organism for several 

 generations under suitable conditions. Experiments on the 

 formation of invertase and of enzymes fermenting glucose 

 and galactose were described. Prof. Euler had been unable 

 to train certain yeasts to acquire the power to ferment 

 galactose. In discussing the paper, Dr. E. F. Armstrong 

 expressed the belief that there was an essential difference 

 between the power to acquire an entirely new enzyme and 

 that of regaining an enzyme, which had not been required 

 by lie yeasl lor many generations, and so had fallen into 

 disuse. The former was impossible, whereas many brewer] 

 yeasts were .,1,1, to regain, as the result of training, the 

 lost property of fermenting galactose. 



In opening a discussion on the part played by enzymes in 

 the economy of plants and animals at a joint meeting of the 

 Chemical and Agricultural Sections, Dr. E. Frankland 

 Armstrong gave a definition of enzymes, pointing out their 

 connection with practically all processes of metabolism in 

 living organisms, and emphasising their specific nature. 

 One function of enzymes is to break down complexes in the 

 cell ; there is a necessity for some restriction of action I 

 otherwise the cell would soon be killed. The safeguards of 

 nature to prevent this were described. Il was shown how 

 the leaves of tin- cherry laurel, which give off hydrogen 

 cyanide, or those of the Japanese laurel, which blacker! 

 can lie used to indicate that changes are taking place in 

 the plant cell. The resting leaf can be stimulated into 

 activity by a number of substances, of which toluene and 

 chloroform are examples, which as a class are characterise! 

 by being chemically inert substances, and further by haying 

 I ui Hull affinity for water. It is suggested that such 

 substances, to which the general name hormone is applied, 

 are able to penetrate the ceil and bring about hvdrolvtic 

 change within it. A large number of substances which 

 ry weak hormones are found in plants combined 

 with glucose, as the so-called glucosides. It is believe] 

 that one function of glucosides is to act as hormones when 

 a specific mild stimulus is required by the plant. Each 

 requires an appropriate enzyme to hydrolyse it 

 before its constituents can be effective as hormones. The 

 speaker alluded to the wide distribution of glucosides in 

 plants, and gave an account of work done in localising and 

 studying their appropriate enzymes. Whereas the leaves 

 of a plant. contain, as a rule, an enzyme adapted only for 

 the glucosidi contained in them, the seeds of the same 

 plant contain an enzyme or mixture of enzymes able to 

 attack a variety of glucosides. The practical application 

 of tins, researches to a number of problems in animal and 

 vegetable physiology and agriculture was illustrated in 

 detail. The discussion was general, and mainly turned on 

 controversial points. 



Idle rest of the morning was devoted to a paper by Mr. 

 A. E. Humphries entitled " Some Points concerning the 

 Treatment of Wheaten Flour." This contained one new 

 poinl ei ven considerable importance, li has been found 

 addition of very small amounts of salts, natural to 

 flour or to the ash of wheat, increases the size of the loaf, 

 though it has no effect on the production oi gas in 

 fermentation. In one instance the mere addition of water 

 to flour, so long as it was made at a time substantial!* 

 prior to dough-making, increased the strength of the flour 

 to an extraordinary extent. Investigation showed that, 

 the addition of water, then was actual change 

 of the organic phosphorus compounds of the flour into 

 inorganic, and that further a still larger proportion of the 

 organic phosphorus compounds are transformed during 

 bread-making. The change is probably enzymic in 



In conclusion, Mr. Humphries alluded to the difficulties 

 millers have I i face, and claimed that they should be 

 allowed to mak> usi ol the advances in chemical know- 

 ledge in the treal I of wheats and flours. 



September 5. was reserved for papers on* 

 colloids. A very admirable and fluent introduction on the 



