摘要:

FROM time to time in these coluilfe the necessity for a new ori thought has been stressed. Wjahave pointed to the changing intricac^ ofj^fftnern life-quickened, illuminated, ennbh|^/s^(flenriched by thdprVictical application ofmminy sciences^arfS'irav Jrankly stated the viejfr that, unless/the~new aspects and forces be deliberately wovenS"to our educational schemes, those schemes are foredoomed to failure. It is our business, however, sedulously to avoid being carried away by any theory which 'will not submit to all possible tests. All the many facets which a single problem may present must be taken into consideration. We do not imagine, for example, that one successful experiment necessarily presents a sound reason for sweeping and immediate alterations to some industrial process which rests upon conditions not always apparent in the laboratory.Such considerations compel us to realise that the educational changes we have in mind cannbt be made impetuously. Time is necessary for the formation of professional no less than public opinion. Environmental factors need adaptation. If, for example, we have urged greater attention to technical education, not only as a sine qua non of industry but also as a vehicle of liberal qualities as yet but dimly apprehended, we have not failed to observe that its success is as much dependent upon its relationships with other forms of education and with industry as it is upon administrative method and teaching power. Is there any proof that advance in these directions is being made? An encouraging answer is to be found in a Report* concerning the provision of chemical instruction in technical institutions, recently issued by the Board of Education. We congratulate the compilers on a brief and excellent piece of work. In the sober and guarded language of an official report, they have done something more than sketch out the volume and character of the provision of instruction in pure chemistry in English technical schools; they have done something more than set out important statistics and comment on the general standard of the work. They have shown clearly the influence of factors upon which we have frequently insisted. They have presented undeniable evidence of definite advance as a result of those factors; and, in spite of their assertion that only pure chemistry is under review, they have, by implication, described the way of further development in other subjects.Notice the result of wider secondary education (in the full meaning of the term) and the growing appreciation of employers of the instruction available. It is now expected that, before admission to a full-time course, a student should have received a secondary school education, though matriculation is not essential: students entering part-time courses need not have been through the ordinary secondary school, but are expected either to have passed through a junior technical course consisting of mathematics, science, drawing, and English, or to show they have some knowledge of these subjects. This improvement is not due solely to the wider provision of varying types of secondary education, but also to "the growing practice of employers in requiring that candidates for junior positions in their laboratories shall have received a superior type of education." Well-organised evening courses, too, are playing a part which is of especial importance when it is noted that, of the 11,000 students taking instruction in pure chemistry, only about 15 per cent, are in full-time attendance (at 32 institutions). In 163 institutions, however, instruction is provided in part-time grouped courses. Insistence is now possible on an adequate standard of training preliminary to admission to evening junior technical courses. " As a consequence a higher standard of attainment is now secured in respect of an increasing number of part-time students."Active interest on the part of employers and better preliminary training cannot, however, produce this higher standard of attainment unless administrative and co-ordinating factors also receive attention. By no means small have been the parts played by examination arrangements. " In the north-west the influence of the Union of Lancashire and Cheshire Institutes has been operative; in the midlands and the south the attraction of a University degree has been more important . . . in Pharmaceutical courses, the new requirements of the Pharmaceutical Society have increased both the numbers of students and the systematic character of their studies," This question of examinations-a vital function in the educational process- is, in its wide implications, still under discussion in connexion with most branches of technical education, and there can be 110 doubt that the National Certificate schemes have gone far to satisfy supporters of the purely internal and of the purely external systems. Nor have examinations arid new requirements fallen with dead and levelling weight upon the institutions: " This degree of organisation has been secured without depriving the schools of their individuality." If any more definite measurement of all-round improvement be necessary, the following extract can scarcely be bettered: "A few years ago the proportion of students attending courses was probably not half what it is now. The standard of admission was lower and less clearly defined, and a large number of students were entering upon the study of applied Chemistry with totally inadequate grounding in Pure Chemistry and with no previous or concurrent instruction in Physics." Now nearly eighty per cent, of part-time students take courses involving attendance on three evenings per week and including the subsidiary subjects of mathematics and physics. There is also a growing tendency to prepare for the associateship of the Institute of Chemistry in both full- and part-time courses.Though, however, the organisation may be excellent, the success of the work must ultimately rest upon the teacher-the final executive officer. In this connexion again the Report is soberly confident. The main work is in the hands of the permanent teachers of the technical school, who are assisted in the evening work by teachers who are employed in the day time in Secondary, Junior Technical or Central Schools, or in industry. A very large proportion of both groups possess graduate or equivalent qualifications. " The general standard is therefore high, and is almost in itself a guarantee of the fullness and accuracy of the instruction." Some points of criticism arise, however, which give an indication of the special qualities which are needed in technical teaching-qualities not always found in teachers trained along the usual academic lines. " Some teachers who have had experience with young students cover the ground too slowly for the older students who attend evening classes, and they waste a good deal of time endeavouring to elicit conclusions from early arid isolated experiments." The use of text-books, too, is not always understood. " Students need to be trained to acquire information for themselves, and the lecture hour is often more profitably devoted to emphasising important points-crealing perspective [our italics] -than in conveying information which can be obtained quite easily from a book."A broad classification of 10,379 students following part - time courses is given. Within the chemical industry 2450 are engaged in laboratory work; 1309 in the factory, and 651 in clerical or commercial work. 2324 are engaged in retail pharmacy and dispensing, while 3645 are absorbed by " other occupations." These figures give peculiar significance to another valuable point to which the Report directs attention. In some schools " insufficient training is given in the simple laboratory operations. The students have not enough practice in fitting up apparatus, and the importance of neatness and tidiness is not sufficiently impressed upon them." We have already noted a not dissimilar criticism in a speech made to the Association of Teachers in Technical Institutions by the ex-president of the Society of Chemical Industry (NATUKE, June 25, p. 942).We hope in observing these defects we do not give any wrong impression. We asked, at the outset, whether any proof was available concerning our own expressed views on the new factors which are slowly to change much current educational theory. The Report provides us with adequate proof, and we shall bear its principles in mind in reviewing subjects other than chemistry. In the meantime, so far as the latter is concerned, the crisp conclusion of the Report stands in need of no adornment. " The teachers as a body are well qualified and generally competent; the accommodation and equipment are, on the whole, good; the organisation of most of the courses is satisfactory; and the defects to which attention has been drawn are the exception rather than the rule." 1 Report of H.M. Inspectors on the Provision of Instruction in Pure Chemistry in the Technical Colleges and Schools in England. Pp. 11. (London: H.M. Stationery Office, 1927.) 3(2. net.

ISSN:0028-0836    

DOI:10.1038/120141a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

(1) THE rivalry of classical wave theory and J- modernist quantum theory has of late years dominated the physics of radiation, and in spite of all our efforts we can scarcely say that a really satisfactory solution is yet in sight. Nowhere is the conflict more acute than in the field of X-rays, and the investigations of the past few years have all gone to emphasise the differences rather than to reconcile the warring interests. On one hand we have the establishment of what might be called the optical properties of X-rays, such as reflection at a glass surface and refraction through a prism, phenomena hitherto always explained in terms of the wave theory: on the other hand, quantum effects of an extreme type have been revealed by the study of the extraordinary effect known by the name of Compton, who first established that for very short X-rays, where the quantum of energy is large, the radiation can be shown to behave in many respects like a minute projectile, the results of whose impacts with an electron can be calculated on the lines of the impacts of massive spheres. Prof. Compton has also been closely interested in many problems which have been worked out in terms of the wave theory, such as the questions of the intensity of X-ray reflection and of X-ray absorption. His recent book on X-rays and electrons has therefore strong claims on our attention. Prof. Compton's book is, broadly speaking, devoted to the discussion of experiments and theories bearing on the physical nature of X-rays, and comparatively little is said of their applications either to the study of crystal structure or to practical questions such as the investigation of fibrous forms, organic or metallic. Much of the first part of the book is devoted, to physical problems of which an explanation can be attempted in terms of classical electromagnetic theory, such as the polarisation of scattered X-rays, the intensity of X-rays reflected from crystals, and the more strictly optical properties of X-rays. Within the last few years, X-rays have been diffracted by ruled gratings,: chiefly by Compton and Doan, and by Thibaud, and a striking photograph is given of a spectrum so obtained. Of course, the accuracy to be expected with this method does not so far approach that obtainable with ordinary crystal methods, but a value for the wave - length of molybdenum Ko. has been obtained which agrees exactly with the crystal determination.A special chapter is devoted to the refraction, in the ordinary optical sense, of X-rays, and the small deviation from Bragg's law wA.=2d sin 0, which has been experimentally detected, is explained in terms of the refractive index, which calculation shows to be slightly less than unity. The total reflection at small glancing angles to be expected from such a value of the index, and the refraction by a prism of glass established by Siegbahn and others, are illustrated by excellent photographs. As Compton emphasises, the experimental determination of the refractive index affords a straightforward method of, determining the total number of extranuclear electrons, and the value so found agrees closely with the atomic number. As is natural, the book contains full references to recent American work, such as Hewlett's repetition of Barkla's work on the scattering of soft X-rays which, oil the basis of J. J. Thomson's classical theory, also gives very satisfactory values for the number of electrons in, for example, the carbon atom. The questions of the intensity of reflection of X-rays from crystals ahd the closely allied questions of absorption are treated in much greater detail than has so far been attempted in any book in English. The well-known work of W. L. Bragg and his collaborators, and the theoretical treatment of the whole problem by C. G. Darwin, are discussed at some length, and recent work by the author and his collaborators and other American workers, which is not yet widely known, is described. Prof. Compton has devoted much research to this part of the subject, and the various ^aspects of the somewhat complicated phenomenon of primary and secondary extinction come up for treatment. The distribution of electrons obtained by W. L. Bragg and by the later American workers depends, of course, upon the laws of classical electrodynamics, and it is not established beyond doubt that they form a valid basis for such calculation.The inability of the classical theory to explain the scattering of hard X-rays is well known, and Prof, Compton's account of his discovery of quantum scattering and the researches which have followed it, especially in America, will be eagerly read. The quantum theory of the change of wavelength which accompanies the scattering of hard X-rays by ' free ' electrons is very simple, and the general features-change of wave-length with angle of scattering, directed scattered quantum and recoil electrons-have been clearly confirmed by experiment. In this field the Wilson cloud chamber has proved its value as an instrument of investigation in a number of daring experiments. When we try to go a little farther, however, the initial simplicity is quickly succeeded by co'mplica-tions and difficxilties. The calculation of the broadening of the unmodified line demands some hypothesis as to the behaviour of the electrons within the atom, that is, we have to take into account the orbital motion of the electron at the moment when it is ' struck ' by the quantum of radiation, and Jauncey's calculation on these lines is only partially satisfactory. The intensity of the scattered X-rays takes us 'still farther into doubtful and difficult fields. Here we may hope for the new quantum mechanics, out of which the Compton effect comes so naturally, to give us some acceptable solution. The points mentioned arc chosen from among some of the most interesting, and do not exhaust the scope of the book. There is, for example, a chapter on familiar lines dealing with X-rays and crystal structure, and another dealing with the elegant and less-known method of treating diffraction by a crystal from the quantum point of view. The treatment in the book is largely mathematical, and greater attention is paid to the theories than to the description of experiments: for example, the account of Compton and Simons' striking cloud experiment on the direction of the scattered quantum is very meagre, and less clear than the short description given by Kallmann and Mark in Ergebnisse der Naturwisf;e,nschaften. Naturally, the work of American investigators receives great prominence, to the relative exclusion of German work. The work of the last few years is really the subject of the book, so that it often happens that partially unsolved problems and incomplete investigations are treated at great length. This actuality of the book will enhance its value to all those engaged in research in these difficult regions, but sometimes renders it tough reading.The general production is excellent, but it is unfortunate that the proof-reading has not been more carefully carried out. The literal misprints are many, but need not trouble the reader, as it requires, for example, little ingenuity to see in Naturious a reference to Naturwissenschaflen, or to see that by IA is meant I. When it comes, however, to being referred back to Fig. 4.05 and finding that it means Pig. 45; to page ix. 23, and having to discover that it means page 280 in chapter ix.; to page 22 when page 241 is meant, and so on, the reader grudges the waste of time. The index is incomplete even beyond the worst of indexes, and may give a false idea of the scope of the book: for example, the names of Dirac, Kuhlen-kampff, Ishino, and many other workers do not occur in it, although there are references to their work in the book. These blemishes, however, are minor defects, which should not damp our appreciation of a book in which a great investigator gives an account of some of the most striking recent investigations in physics, of which he himself has been a great part.(2) The reports on contemporary advances in physics, published by Dr. Darrow in the-...BeZZ System Technical Journal, and distributed in separate form, arc known to many physicists: ^ Dr. Darrow, who is a member of the staff of the Bell Telephone Laboratories, has now brought out a book based on them. The " Contemporary Physics " of the title refers to what may be called the physics of atoms and rays, and no attempt is made to cover the whole field of physics. Within " the range chosen, Dr. Darrow has made an excellent selection of material, which includes much important American work not hitherto quoted in text-books. The disconnected nature of the original articles, each of which referred to some one topical branch of investigation, has not been entirely eliminated in the book, so that we find some overlapping, and an order which must sometimes prove disconcerting to the student. Thus ionisation and radiation potentials are discussed in Chapter vii., while elastic and inelastic impact are first defined in a subsequent chapter, and an account of Bohr's atom model is given still later. The final chapter, v which follows the epilogue, is a practically independent dissertation on the conduction of electricity through gases. The separate chapters make very interesting reading, for the author has picked out for treatment the phenomena on which theo attention is chiefly concentrated at the present time, and the book is embellished by a number of pertinent photographs illustrating various features of modern work on spectra, which are not, however, v very clearly reproduced in some cases. Dr. Darrow's book, like Prof. Compton's, serves to remind us of the enormous amount of purely scientific work now being carried on in great laboratories of America, both those of k universities and those attached to great commercial concerns.

ISSN:0028-0836    

DOI:10.1038/120143a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IT is now nearly twenty years since a considerable J- number of agronomists in Great Britian have reached the opinion that agricultural field trials, whether concerned primarily with manures or with varieties, if they were to afford practical guidance to the farmer, must be carried out with increased precision. The important preliminary work of exploring the variability of yield by uniformity trials was performed for England in two excellent investigations by Wood and Stratton at Cambridge r and by Mercer and Hall at Rothamsted. At about the same time, by what is not necessarily a co-incidence, a fundamental advance in the theory of errors, which renders possible the exact treatment of the evidence of small samples, was made by that anonymous genius who disguises his identity under the pseudonym of " Student." Since that time the work of applying the knowledge gained to the practical refinement of agricultural experimentation has been actively carried on by Dr. Beaven at Warminster, and more recently in the Statistical and Field Department at Rothamsted; it would scarcely be an exaggeration to regard "Student" as the spiritual father of both developments. The recent memoir by F. L. Engledow and G. Udny Yule on the " Principles and Practice of Yield Trials " represents another case of the cooperation between the statistical and the experimental phases of the same large problem. It is divided into two sections, of which the first includes an explanation of the statistical methods advocated, while the second deals with " practical considerations and procedure." Commencing with Mercer and Hall's data in their uniformity trial with wheat, the reader receives a clear explanation of why an experiment, comparing the yields of single half-acre plots, may be expected to yield errors of the order of 5 per cent.; and of how much higher accuracy is attained by utilising the same area under smaller replicated plots. A statistical treatment is given for replicated plots, and a table of the normal distribution is provided and its use explained for finding the probability of exceeding by chance a given multiple of the standard error as estimated. Theoretical and practical limitations of the formula are then discussed, the principal of the latter being that ascribed to the differential response of varieties to climatic variations.In the second portion we do not hear so much of " practical considerations " as we might have hoped from the title, for the authors devote most of the available space, as they naively say, " to explain broad questions of policy," so that we are left much in the dark as to their opinions on many practical details. Only variety trials are discussed, and these only with cereals. The treatment is less systematic than that of the first part, and we are seldom allowed to forget, for more than a few paragraphs, how comparatively unimportant the author considers yield trials in general, and in particular the improvements in accuracy of which they are susceptible. It is difficult to summarise this section. The first three portions seem designed to assert, at some length, that (i) varietal differences in quality are often more important than yield; (ii) qualitative differences should govern the choice of varieties for yield trials; (iii) the significance of yield-trial results is limited by their not being performed by industrial farm methods. The fourth, fifth, and seventh portions are devoted to observation plots, an important subject, upon which the author speaks with authority, but which unfortunately can scarcely provide a preliminary opinion as to yield, much less a measure of it. Yield trials on the plan denoted ' chessboard ' are most carefully described; it should be noted that the author limits this extremely vague term to small trials carried out under a wire cage, with individual seeds dibbled at regular intervals, on a fine tilth; the ' plots ' are about a yard square. The reader of this portion will realise the force of the strictures previously developed upon the limited agricultural significance of trials, which depart from the methods of practical farming, but will wonder why no distinction was there made between ' chessboard ' trials of this type and the better-known methods of plot replication in the open field, A second valuable portion is the description of Beaven's half-drill strip method. Unfortunately, this is the only field method discussed. The last two portions on the size and arrangements of plots, and on ' corrections' for soil irregularities, have perhaps been hurriedly written, and without any very full consideration of the subject.The authors have missed the fact that the method developed, following " Student," in Section I., is (equivalent to a method of ' corrections ' stigmatised on p. 75; as, indeed, is necessarily any method Oi eliminating a portion of the soil heterogeneity. The fact also, that " Student " had shown eighteen years before that precise values of the probability may be obtained in tests of significance with small samples, is overlooked on p. 77, where it is asserted that " in agricultural work with a very small sample (e.g. of four or five observations) the value of P, however obtained, is quite untrustworthy." This criticism should of course be confined to the methods here expounded; the great beauty of " Student's " treatment lies in the fact that it does give trustworthy tests of significance, within the scope of agricultural experimentation. Apart from this omission, statistical criticisms will naturally be few. It appears unfortunate that in developing " Student's " method of treatment of a replicated experiment, the estimation of residual errors has been changed in such a way as to produce, in some cases, a serious under-estimate. A point, which is likely to be in some ways more misleading, lies in the use on p. 30 of the standard error appropriate to a pair of varieties chosen at random, to test successive differences of a number of varieties set out in order of yield. This procedure is often grossly misleading, since the best and worst of a set of random yields from the same variety will often show ' significant' differences if tested in this way. The curiously pessimistic tone as to the value of yield trials which influences both sections of the book is perhaps to be ascribed to a somewhat unexpected limitation of outlook as to the scientific purposes which such trials serve. After giving reasons for thinking that the differential response of varieties grown in different years may be so much as 5 per cent., a figure which the reviewer does not consider exaggerated, the authors continue (p. 33):" In view of such results, it may well be. asked, what is the value of these elaborate tests? The answer, though it may seem pessimistic to some, must be, we think, that it is very little or, if the phrase is preferred, extremely limited. Even in so far as the investigator is concerned with yield alone-and usually he is equally concerned with other qualities-he is concerned with the average relative yields over successive years." It does not seem to have occurred to either author that a knowledge of these differential responses to weather or soil would itself be of extreme agricultural importance in the practical choice of varieties; and that such knowledge would do much to remove the real grievance of innumerable farmers who grow, for example, wheat in the west, or turnips in the south, of England, far from the centres of the industry, where research is properly concentrated. On the contrary, both effects are looked upon merely as ' errors ' to be averaged out by interminable repetition. This same consideration of differential weather responses evidently also underlies tjie numerous passages decrying attempts to increase accuracy. To adduce the importance of qualitative differences as a reason for neglecting accurate yield trials appears to the writer at least equally farfetched. After all, the demand for higher yielding varieties comes straight from the practical farmer, and, however difficult the experimenter may find it to attain adequate accuracy to meet this demand, it is a mere evasion of the difficulty to discant upon the importance, which no one denies, of qualitative differences. How the practical adviser is to weigh qualitative advantages against a loss of yield, or vice versa, without an accurate knowledge of the yield factor, is nowhere explained.For these weaknesses it is probable that neither author would be to blame had the book been published either earlier or later- by a few years; a few years ago, the theory on which the Latin Square and other ' randomised ' systems are based had not been developed, and in a few years' time the lessons learnt from their use, whether more or less favourable to these methods, will be sufficiently well known, even to writers without personal experience of their working. At the moment they are in the difficult position of judging of the newer developments in experimental theory and technique, by the standards of an older theory and technique, the defects and inconsistencies of which it is the avowed purpose of the newer methods to correct. It is the paradox of the present situation that cotton growers overseas should be putting into practice the applications of just these newer theoretical developments, which their academic mentors would have them regard as impracticable.

ISSN:0028-0836    

DOI:10.1038/120145a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IN recent years the empirical descriptive methods of an older generation of petrologists have been fortified by exact experimental work in fields of high temperatures and pressures; and some knowledge of the more notable results that have been achieved, and of the fundamental principles of physical chemistry on which they are based, has now become an indispensable part of the equipment of a modern petrologist. The steady stream of publications from the Geophysical Laboratory at Washington, and from various European workers such as Vogt and Niggli. indicates the increasing importance of chemical thermodynamics in revealing the processes which rocks have undergone. Hitherto, however, there has not been in English any systematic introduction to physical chemistry in its application to geological problems. Dr. Rastall will earn the gratitude of a wide range of students by providing this excellent foundation for more extensive studies. The first four chapters deal with the basal conceptions of equilibrium and the phase rule, and with the phenomena of fusion and solidification, solution and crystallisation, isomorphism and polymorphism. The principles having been clearly established and illustrated by cogent mineralogical examples, the author passes on to their application to igneous rocks. These are polycomponent systems, so complex that a satisfactory phase rule discussion is generally out of the question. Nevertheless, the ternary systems embraced in the group of components Si02-MgO-CaO-A12O3, and the systems albite-anorthite, diopside-plagioclase, and orthoclase-silica, all of which have been worked out fairly completely under anhydrous conditions, have made it possible to consider some of the simpler magmas and their cooling histories with very successful results.Little is known as yet of the quantitative effects of volatile fluxes, though preliminary work in simple cases with water and carbon dioxide as the volatiles has already encouraged the geophysical workers at Washington to more ambitious attempts to conquer this difficult field. It is probably here that the most brilliant conquests will ultimately be made, for already Th. Vogt has shown that the pncumatolytic and hydrothermal stages in the cooling of a magma can be explained on physico-chemical grounds. Moreover, increasing attention is now being given to the separation and transfer of gaseous phases as an active process in causing differentiation, facilitating assimilation, promoting metasomatism and concentrating ores. These topics are still largely confined to more or less speculative discussions of field observations, and, perhaps rightly in an elementary book, Dr. Rastall has touched on them but sparingly. His discussion of differentiation, however, clearly shows that, despite the work of Brogger, Harker, Bowen and many others, the mystery of the general problem still remains to be solved. Dr. Rastall puts his finger on the core of the difficulty when he writes: '' There is no experimental evidence at all in support of the theory that a silicate melt tends to split into two conjugate solutions. Nevertheless many of the facts of Nature indicate pretty clearly that something of the sort does occur." It is suggested that there is no justification for the recognition of the spilitic suite of rocks on the ground that its members differ from the ' true alkaline rocks ' only in having soda in considerable excess of potash. But they appear in a totally different structural environment from typical alkaline rocks, and if Shand's clean-cut definition of the latter be accepted, then most spilites are not technically alkaline at all. The recognition of a spilitic suite should not be described as an attempt to confuse the issue (p. 95); rather, it is an attempt to clarify an issue that is at present excessively confused.The integration of processes described as meta-morphism is next treated. Here many mineral associations are clearly deducible from the phase rule; but where differential pressure has operated, the natural conditions again rapidly pass out of the present scope of experimentation. Thermo-dynamic principles lead to the important deduction that differential pressure lowers the melting point. This curious fact, so remarkable to the beginner, has endless applications, and it is a disappointment to find it merely stated without a graphical demonstration. Weathering is very properly separated from jnetamorphism, for its processes involve the reactions of aqueous solutions in an environment of low pressure and fluctuating but relatively low temperatures. Despite the apparent simplicity, the conditions are taiitalisingly complex from the point of view of physical chemistry. The peculiar properties of surfaces, capillary spaces, and colloids (the last briefly treated in the final chapter) all require fuller investigation, and still further complication is introduced by the uncertain influence of bacterial activity.Little reference is made to the conditions that control the cementation of sediments and the growth of concretions. This is a subject that has been strangely neglected, and a systematic treatment in a book of this kind would be widely appreciated. The precipitation of saline deposits from surface waters is, on the other hand, a subject that has been thoroughly tidied up, thanks to the familiar investigations made by Van't Hoff and his colleagues. The results are briefly reviewed in a chapter on salt deposits, in which is also included an account of the origin, still vaguely understood, of the carbonate formations, including dolomite. The two remaining chapters are devoted to ore deposits and refractories and abrasives, branches of economic geology on which Dr. Rastall speaks with the personal authority of a wide experience. Dr. Rastall has skilfully avoided the tempting atmosphere of speculation. He has surveyed his subject with commendable restraint, and produced a clearly written and trustworthy book which reveals both the strength and the limitations of the methods of physical chemistry. To know that the natural interplay of energies in the earth is too complex for complete imitation is a mental tonic rather than a cause for depression. To know that laterite, dolomite, lamprophyres, and many another puzzling rock still present baffling problems to be solved, merely adds to their fascination; and when all is said, one feels, after considering the subject matter of this book, that Sederholm is thoroughly justified in his insistence that geology is very much more than applied physics and chemistry.

ISSN:0028-0836    

DOI:10.1038/120147a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THE publisher of the International Library of Psychology, Philosophy, and Scientific Method are to be congratulated not only on the inclusion in their collection of this peculiarly interesting addition to biological thought, but also on securing the services of such an able translator. Reference to Dr. D. L. Mackinnon's name on the title-page is necessary before the fact of translation is realised. In this " Theoretical Biology," von Uexkull discusses modern biological concepts, and summarises them in relation, to his extended application of Kantian philosophy to the animal world. Biological science has come to a deadlock by having been too greatly dominated by the physicist's insistence on an objective world, whereas the true secret of understanding is to be found not behind objects but subjects. The observer's viewpoint must of necessity be outside this subjective world, and when this fact is clearly realised, investigation can proceed.The mechanical processes of the organism reveal a conformation to a rule of Nature, which is not merely a mechanical law, but also indicates that there is a super-mechanical factor at work. With the production of a new framework, a process which takes place within every cell, repair proceeds from within. In a machine, this need for reconstruction must be dealt with from without, therefore here is an example of this super-mechanical factor, or ' impulse,' as von Uexkull calls it. Invasion of a cell by impulses is always followed by the formation of a new framework, and consequently the impulses are referable to an influence exerted by the genes on the protoplasm. These impulse-systems are not regarded as a ' psychical world-factor'-on the contrary, von Uexkull anticipates their isolation, since already there are indications that transference of form-giving impulses can take place. Thus they are part of an "objective conformity with plan," a biological doctrine into which " Lamarckism would pass straight over, would it but throw off its psychological wrappings." There is no question of ' purpose ' or ' purposefulness,' as is generally understood by the idea of ' conformity with plan.' von Uexkull deplores the fact that the personification of Nature, which conception has occupied the minds of men for so long, cannot be dismissed once and for all from the realms of bio logical thought, and with it the inability to recognise " limits to the possibility of knowledge," so that full attention can be given to the acquisition of those positive additions to knowledge by means of which alone real progress can be made.

ISSN:0028-0836    

DOI:10.1038/120148a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THE authors of this book state that it has been their endeavour to collect in as concise a form as possible the available information in regard to enzymes and to indicate the original sources from which more detailed knowledge may be obtained. To piece these irregular and loosely fitting fragments together has been their object. Special attention has, they say, been paid to the occurrence and preparation of enzymes, to the methods of the measurement of their activity, and to the practical application of these agents. The text is divided into four sections, each of which is subdivided into chapters as follows: (a) Properties of enzymes (four chapters); (b) distribution of enzymes (three chapters); (c) methods for the preparation and study of enzymes (seven chapters); (d) practical application of enzyme activity (one chapter).There is a bibliography giving references to 1323 original papers, none of which, however, is later than 1925. The book is brought to a close with an index. The introductory chapter gives an outline of the history, general characteristics, nomenclature and classification of enzymes. The next three chapters deal with chemistry, biology, and physics. The major portion of the next chapter is devoted to the occurrence and distribution of enzymes in animal secretions and tissues. This is followed by two shorter chapters on the enzymes of the higher plants and of micro-organisms.The section commencing with Chapter viii. is the longest in the book, covering as it does 128 pages of text. Although containing some most useful information, clearly set forth and well arranged, it is here that we venture to make some criticism. Under methods of measuring diastatic action, the authors describe Wohlgemuth's iodine method and Lintner's saccharometric method. In regard to the latter, a modification is described which is more complicated and does not appear to lead to increased accuracy. No mention is made of the titration method devised by Prof. A. R. Ling, which has been adopted by the Institute of Brewing as one of the standard methods of malt analysis. Nor is there any mention that when the activity of malt diastase is measured by a saccharometric method, the production of reducing sugar must be kept within the limits laid down by Kjeldahl in 1879 if the results obtained with two or more samples are to stand in direct proportion. In dealing with the synthetic action of enzymes, the work of Bourquelot-by far the most important on the subject-is not alluded to in the text. In that part of the book dealing with desmolases- oxidases, oxido-reductases, and zymases-sometimes the difference between supposed direct oxidase action and dehydrase action is described in a manner likely to prove misleading to the student. The authors make no reference to the discovery by Hopkins in 1921 of an autoxidisable constituent of the cell which he named glutathione, although they do refer to the significance in respiration of substances containing the thiol group SH which is present in reduced glutathione. Another serious omission is that of a reference to the recent work of Robison on the part played by calcium hexosephosphate and its enzyme on ossification and dentition.If there are defects in the preceding parts of this book, there are more pronounced cases in the last chapter which deals with the uses of enzymes. Barley is said to absorb 40-50 per cent, of its weight of water in the steeping process-the first in the conversion of barley into malt. The fact is that barley after steeping contains about 50 per cent, of water. In describing the mashing process the temperatures given are 23°-13° C. too low for distillery practice and 26°-16° C. too low for brewery practice. The subject matter on the hydrolysis of starch by enzymes given in the book is out-of-date, as is also that dealing with the estimation of starch by enzymes, and the latest methods adopted in England find no mention. These are only a few of the defects which cowld be cited. We close our review with a feeling of disappointment. Some portions of the book are such a's to recommend it, whilst others show that the authors have omitted important observations or have failed to understand the true significance of some points to which they have referred. It is hoped that a new edition will be published in the near future in which the entire work will be recast, for the authors have not attained the objects which they set themselves to achi

ISSN:0028-0836    

DOI:10.1038/120149a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THIS volume is the third of the series of " Practical Coal Production " and may be looked upon as a continuation of the two previous ones, which have already been discussed in these columns. The present volume is no advance on its predecessors, showing quite as strongly as they do the defects previously indicated, and being perhaps even more ' scrappy ' than either of the others. It contains three chapters, on mine transportation, hoisting and hoisting equipment, and coal preparation respectively. The first part consists of a miscellaneous collection of information concerning animal and locomotive transport underground; perhaps the best point about this section is the considerable attention paid to underground track work, the importance of which is just beginning to be recognised by colliery managers. Chapter ii. is almost wholly taken up by calculations, such important matters as the construction and design of cages and headgears not being even mentioned. Having regard to the recent developments in American coal mining, one would have expected to have found some information, at any rate, as to the employment of skips instead of cages, but this again has been entirely neglected. The third chapter is taken up mainly with coal conveying and screening. The author is aware of coal washing, but he dismisses it in a few lines, as though it were not in fact the most important part of coal preparation at the present day. The author's lack of knowledge of what has been done in Great Britain again makes itself manifest at various points; thus he describes as an entirely novel invention screens, which he calls weight-vibrated, being evidently unaware that theappliance he is describing is simply the old Beaumont vibro-motor invented years ago in England. Whilst the book is well got up, misprints are more numerous than they should be. Perhaps the most noteworthy one is a caption on p. 3, " Insulting the Mule," when it is obvious from the context that the author must have written/' Insulating."

ISSN:0028-0836    

DOI:10.1038/120150a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THE original collection of true Irish ghost stories appeared jariQty, and elicited a large number of additional examples which warranted a second and enlarged edition; but publication was delayed owing to the War. The re-issue is justified by the additions. The collection covers a wide range of phenomena. The three chapters which are devoted to haunted houses include some remarkable experiences, many of which are off the familiar track. One quoted from the Occult Re-view describes the apparition of what was clearly an elemental with characteristic hairless face and unpleasant stench. The poltergeist stories, as compared with some which have appeared recently in. the Press in England, are, on the whole, disappointing as psychic manifestations, and indeed, except in the cases recorded by the late Sir W. Barrett, resemble folk-tales relating to these appearances rather than genuine experiences. Of the ancestral ghosts, some are already familiar to students of folklore, among them being the Gormanstown foxes, real foxes which on one occasion appeared in Dublin itself. There are several cases of invisible ghosts. One, if invisible, was ponderable, for when it jumped on the handle bar of a bicycle the rider was compelled to. pedal down a steep hill. Of apparitions before, at, and after death, and of the banshee, there are, as might be expected, numerous examples. The compilers present the stories without comment, and of course do not guarantee their genuineness.

ISSN:0028-0836    

DOI:10.1038/120151c0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IN this shop-monograph the late Prof. Cushny has given an account of the pharmacological behaviour of those drugs which exist in an optically isomerio form. Starting from Pasteur's work on the separation of the two forms of tartaric acid by means of the differences in their crystalline form, the author describes how optical isomers can be separated by combining them with another substance which is itself optically active or by means of physical agents, such as heat, which in certain cases lead to the development of different properties by the two isomers. The relation of enzymes to optical isomers and the fate of the latter in the living tissues are then dealt with. Following a section on their pharmacological action, to our knowledge of which the author himself contributed by his researches, the final and most interesting chapter is devoted to some general aspects of this subject. It appears probable that the specific activity of a drug depends on three factors: the general structure of the molecule, some special grouping, such as the alcoholic OH in the side chain of the acid in hyoscyaminc, and, finally the presence of an asymmetric carbon atom. It is the latter which leads to a chemical^combination between the drug and the cell, but rtJJSwin the second property that its specific action chiefly depends.

ISSN:0028-0836    

DOI:10.1038/120152a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IT has been known for a long time that variations in the annual mean values of the daily magnetic range were closely related to variations in the annual sunspot numbers. During recent months a number of other widely different terrestrial phenomena have been found correlated to some extent, at least, with solar changes and with each other.Dr. C. G. Abbot has found that the monthly mean values of solar radiation show variations of the same character as do the monthly and annual sunspot numbers (U.S. Monthly Weather Review, vol. 54, No. 5, May 1926). Mr. Greenleaf Pickard showed that there was a marked correlation between variations in sunspot numbers and radio reception at Newton, Massachusetts, and at Washington, D.C. The comparisons were made with wave-lengths of 8-9 megacycles, 15-25 kilocycles, and 1330 kilocycles. The measurements of the 8-9 megacycles and 1330 kilocycles were made at night, and those of the 15-25 kilocycles were made during daylight (Institute of Radio-Engineers, session of Jan. 10, 1927). Dr. L. W. Austin, of the U.S. Bureau of Standards, has shown that there is a strong correlation between the monthly means of radio receptivity and the monthly means of the Smithsonian measurements of solar radiation, and Dr. C. G. Abbot has found a marked relation between the total solar radiation and the ultra-violet radiation as measured by Dr. Pettit of the Mount Wilson Observatory. However, the variation in ultra-violet radiation is much larger, showing a range of about 60 per cent., while the total radiation shows a range of less than 5 per cent. (Smithsonian Miscellaneous Collections, vol. 80, No. 2, April 1927). FIG. 1.During the past two years Dr. G. M. B. Dobson, Dr. D. N. Harrison, and A. Lawrence, S. J., have made measurements of the amount of ozone in the earth's atmosphere at Oxford (Proc. Boy. Soc., A, vol. 114; 1927). The monthly means of these values show an inverse relation to the monthly means of solar radiation as measured by the Smithsonian Institution and also to Dr. Wolfer's sunspot numbers. In the accompanying plot (Fig. 1) the continuous line shows the variations in the monthly means of ozone at Oxford, the broken curve shows the variations in solar radiation, and the dotted curve shows the variations in the monthly sunspot numbers. The following table gives the departures of these three elements from the means of 19 months, using all the data available from Oxford. The mean values are, for ozone, 0-284 cm. of pure gas, sunspots 52, solar radiation, 1-940 gm. cal. per sq. cm. per sec.DEPARTURES FROM MEANS OF 19 MONTHS. 1925 1926Ozone.1 Sun-spots. Solar Rad." Ozone.1 Sun-spots. Solar Had.8 Feb. + 56 -29 -4 Feb. - 6 + 17 -1Mar. + 20 -34 -9 Mar. + 6 + 12 + 1 April May + 56 + 37 -20 - 9 -7+ 3 April May + 5+ 29 -13+ 12 -7 -6June + 12 - 4 June + 17 + 20 -3 July + 5 -13 + 5 July -18 - 4 0Aug. -11 -14 + 2 Aug. -26 + 11 + 2 Sept. -18 + 8 + 8 Sept. -56 + 9 + 1Oct. -45 +17 + 6 Oct. -52 + 26 -2 Nov. -37 + 7 + 8 Nov.Unit 0-001 cm. 2 Unit 0-001 gm. cal.From these numbers the correlation coefficient for ozone and sunspot numbers comes out, r - - 0-62j:0-09, and for ozone and solar radiation, r= -0-54±0-11. Presumably the correlation would be even higher with Dr. Pettit's measurements of ultra-violet solar radiation, but the figures of his measurements are not at hand. Dr. Dobson and his associates believe that there is an annual period shown by the ozone measurements, and there probably is such a period, but its value cannot be determined from the data at hand; because while the ozone values decreased from about April to October in both years, it happens that the sunspot numbers and also the solar radiation values (both those of Abbot and Pettit) increased from April to October in each year, and as there is an apparent negative correlation between these values and ozone at Oxford, it will take a number of years of observation to determine the terrestrial influence.When the variations shown by the monthly means are eliminated and the day-to-day residuals are compared with sunspots, the relation between them is not evident. In 1925 the correlation coefficient was negative and in 1926 it was positive. But this result is not surprising. Dr. L. A. Bauer and C. R. Duvall found that the same thing was true of terrestrial magnetic variations (Terrestrial Magnetism and Atmospheric Electricity, Dec. 1925). The relation of. these day-to-day magnetic variations to solar changes is different from that of the monthly means and its laws remain yet to be determined. In the case of solar radiation, the short period changes are connected in some way with the passage of spots with their accompanying clouds of calcium across the central part of the sun's disc, as I pointed out in NATURE of Jan. 13, 1921, p. 630. Dr. Dobson and his associates have shown that there is a very close relation between the day-to-day variations of ozone and the variations in pressure and temperature, more especially in the upper air. If future observations shall confirm the relation between the ozone values and variationsin terrestrial magnetis m and relate these to solar changes, they may furnish the key as to how solar radiation changes influence our atmosphere. Dr. Dobson has now -established a network of stations for observing ozone, the preliminary results of which appear to show that there is an increase in the quantity of ozone and its variability from the tropics towards the pole. Since the ozone is found chiefly in the stratosphere, it may be that the increase of ozone with increase of latitude is associated with the increase in the depth of the stratosphere which is found with increasing latitude. The increased depth of the stratosphere over areas of low pressure may also explain the increase of ozone with decrease of pressure in high latitudes

ISSN:0028-0836    

DOI:10.1038/120153a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature