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work, depresses the standard of efficiency for Kafir labour. The best workers are, of course, the few

who spend their earnings (unfortunately largely in THE RAND THROUGH FRENCH SPEC

the consumption of alcohol), and consequently remain TACLES.

on the mining field.”

The author calculates that in the territories in Étude sur l'État actuel des Mines du Transvaal. Les

which recruiting for native labour is permitted a Gites-leur Valeur. Étude industrielle et financière. supply of not more than 250,000 can be reckoned By George Moreau. Pp. iv +218. · (Paris : Librairie The labour requirements of South Africa (for polytechnique, Ch. Béranger, Editeur, 1906.)

mines, agriculture, and public works) amount at pre'HIS, the latest description of the Witwatersrand, sent to 380,000, and if the developments that are hoped

is a curious medley of history, physiography, for are realised, the demand for labour will have ingeology, mining, and finance, in which the author creased in five years' time to 600,000. It is evident endeavours, and not without success, to picture to that the importation of Chinese labour relieved a very his readers the present condition of the gold-mining pressing necessity. industry.

The introduction of the Chinese receives the comThe geological portion of the book consists of a mendation of the author. It has, on the whole, he

says, lications of the Geological Society of South Africa, Very industrious and most desirous of gain, while the mining and economic statistics are derived

the Chinese make first-class miners. They take

are chiefly from the excellent compilations of the Wit- to underground work, and the results

cellent when they know that they are being paid watersrand Chamber of Mines and the Government

in proportion to the work done. While they exert Mines Department of the Transvaal. The descrip- themselves as little as possible when on salary, they tion of the methods employed in the exploitation of show great activity when put on piece-work.' the mines, and of the processes in vogue for the

There is no doubt that if they are employed on piecerecovery of the gold from the ore during its progress

work excellent results will be obtained. Moreover, the froin the rock-crushers, through the stamp-mill and

introduction of the Celestials has, according to the the cyanide works, to the residue dumps, is well done

author, had a particularly favourable influence on the and up to date, such recent innovations on the Rand recruiting of the Kafirs, who now feel that they are as tube-mills and filter-presses being described.

no longer masters of the situation. The use of the old chemical symbols (in which The white miners come in for some severe handling water is represented by HO) in giving the reactions

at the hands of the author. He ridicules their anof the cyanide process seems a strange reversion to tagonism which forced the Transvaal administration, the past. The author's reason for this procedure is in admitting the Chinese, to impose restrictions which found in a footnote on p. 165. It runs :

prevent their best qualities being utilised. The em"Nous avons hésité pour choisir les notations des for- ployment of a Celestial on anything approaching mules chimiques et avons fini par adopter les vieilles skilled labour is strictly prohibited. Yet, as the formules des équivalents. Les nouvelles vues rela

author points out, the machine-drills are often actually tives à la constitution des corps ont provoqué bien manipulated by a Chinese or Kafir assistant (whose des attaques contre les théories dites atomiques et beaucoup de bons esprits regardent cette notation pay does not amount to more than three or four comme insuffisante. Nous ne prenons nullement shillings a day), while the white miner in charge position dans le débat et choisissons simplement les (who draws one pound or more a day) looks on and formules pondérales comme

commode pour les smokes his pipe. praticiens.

In concluding a chapter on the future of the WitA curious commentary on the chemistry of the day! watersrand mining industry, the author says :

Not the least interesting part of the book is that “The Transvaal is a fine country, where Nature has which contains the author's views on the labour supply been pleased to concentrate enormous mineral wealth, for the mines--the burning question of the hour in

and where there is still a fertile field to exploit. Gold and the Transvaal. Speaking of Kafir labour, he says,

coal have been found in abundance." The diamond

occurs in an eminently favourable condition for ex* whereas among the white working classes continuous ploitation, and a recent notable discovery has added work is necessitated by the fact that a day's pay scarcely tin to the metals—lead, silver, and copper—which suffices to meet a day's requirements, the Kafir has no were already known to exist. The possibilities of wants (his food and lodging being found), and he works the Transvaal are considerable, and those who interest only for six or eight months, during which time he themselves in a good venture from the start are accumulates sufficient capital to enable him to return

almost certain to net a profit. The reverse of the

medal is that the European markets do not get the to his kraal, where he invests his savings in women

chance of participating in South African ventures and cattle. The work of his wives then provides the until they have passed through the hands of a number wherewithal for an idle life. Formerly, war furnished of intermediaries, all of whom have exacted a profit, forth slaves for the conquerors; now the males con

and the price at which they are finally offered to sent to a little temporary fatigue in order to assure

the investing public is more in harmony with the

illusions of the purchasers than the reality of the a life of complete tranquillity and repose. The con

facts.” stant succession of fresh hands, inexperienced in mine

F. H. H.




described, except in the case of the more well-known | This book is one of the handy monographs in the


horse-chestnut is here definitely settled. In most Conspectus Florae Graecae. Auctore E. de Halácsy. books Asia is given as the native country of Æsculus

3 vols. Vol. i., pp. 825; vol. ii., pp. 612; vol. iii., hippocastanum; in others it is stated with equal cerpp. 520. (Leipzig : W. Engelmann, 1900–1904.)

tainty that its native country is uncertain or

known. Sibthorp records it as occurring in a wild SINCE INCE the publication of Sibthorp and Smith's great work, Prodromus Floræ Graecæ," more

state near Pindus. Nyman, in a note in his “ Conthan a century ago, a large number of individual spectus Floræ Europææ,” says, “ Indicatur a Sibworkers have published floras of certain parts of thorpio in Pindo, monte illo Graec. bor. sed post eum Greece, and have described a very considerable number a nullo alio ibi inventa est." Halácsy, however, quotes of new species. But no work dealing with the

Haussknecht as having found it truly wild in this Grecian flora as a whole has—since Sibthorp and

and other localities (see Mitth. thür. bot. Ver. 1886. Smith-been attempted until now. The author of the

p. 71). It was, however, Heldreich (in Sitzungsb, present work is to be congratulated upon the success

bot. Ver. Brandenb., 1879, p. 139, and 1882, p. 20) he has achieved. His book is most useful to every

who first brought forward sufficient evidence to prove systematist who has to deal with European plants.

that the real home of the horse-chestnut was in He himself had travelled and collected in Greece, and

the mountains of Northern Greece.

N. had written on the botany of Greece. To the results of his own observations he has utilised the data furnished by previous authors, whose names and

SUBTERRANEAN GEOGRAPHY. works are duly tabulated at the end of the third volume. Höhlenkunde, mit Berucksichtigung der KarstphänoThe area treated in the " Conspectus" is Greece

By Dr. W. von Knebel. Pp. xvi +222. (as politically understood), as well as Epirus and (Brunswick : Vieweg und Sohn, 1906.) Price 5.50 Crete. The three volumes contain 825, 612, and marks. 520 pages respectively. The species are accurately


Die Wissenschaft," which plants, of which bibliographical references and syn- corresponds well in range with the English “Interonyms, as well as habitats, only are given. The

national Scientific Series." It may be described as a larger genera have a key at the commencement of

clear introduction to the study of caves; but it is not each to facilitate the “ running down ” of the species. so inspiring as the subject deserves. We cannot

Practically the sequence of the genera is that of think, for instance, that it would enable anyone 10 Bentham and Hooker's “ Genera Plantarum,”although realise the attraction that the hidden depths have had some of the suborders of those botanists are given for certain specialists. There is a tendency in the independent rank. For instance, Fumariaceæ is

book to classify phenomena, which may be of service separated from Papaveraceæ, Oxalidaceæ from Ger

to those who fully grasp their meaning; and perhaps aniaceæ, Rosacea (as understood by Bentham and

we expect too much from an author who is so eminHooker) is split up into Amygdalaceæ, Rosaceæ, and ently exact. Somehow we do not quite see before us Pomaceæ. Silenaceæ (Caryophyllaceæ of most sys

the great gouffres leading vertically down to unknown tematists) has Alsinaceæ separated from it.

waterways; nor, on the surface, the real desolation It may be of interest to note the relative space of the Karstland, the white dust of waterless dayu, occupied by some of the larger natural orders. Com

the fantastic rocks standing up in moonlight like positæ heads the list with 245 pages, Papilionaceæ ghosts upon the slabs of enormous tombs, the sudden comes next with 125, Gramineæ and Labiatæ have 120

edge of the ravine, and the clear green river sunk each, Umbelliferæ 88, and Scrophulariaceæ 74. The

half-a-mile below. Well, if we are to study “ Höhlenlargest genera in point of number of species are as

kunde," the emotions are for other moments.

Yet follow. To show at a glance the relative propor

what an emotional subject it all is! tions of the Greek to the general European flora

Dr. von Knebel's account (p. 57) of the subtergiven in Nyman's“ Conspectus Floræ Europææ,” the

ranean connection between the Danube at Immen. number given by Halácsy is quoted figst, and then dingen and a tributary of the Rhine in the Hegau the total number for the whole of Europe from

leaves, let us admit, nothing to be desired; and there Nyman. Of Centaurea, Greece boasts 71 species, the

are plenty of local touches here. Of equal interest whole of Europe 171; Trifolium 61 species against is the description (p. 107) of the flow of sea-water into 108, Euphorbia 44 against 107, Campanula 43 against the limestone near Argostoli in Kephalonia, whereby 94; Allium has more than half the total number two mills are kept going in the stream. A diagram of species possessed by the whole of Europe, 41 shows us how this may be accounted for by the outflow against 78; in Verbascum Greece claims a still larger of lighter brackish water into the sea at another point, proportion, 39 species against 54. In Carex Greece this water being the result of the mingling of a freshhas 36 species, the European flora altogether 163. water spring with the marine flow underground. We Vicia has 35 species; Nyman enumerates 61 for learn also how a fresh-water spring emerging under Europe. Astragalus has 33 Greek species against 120 the sea may draw in sea-water from some point above for the whole of Europe, and Hieracium has only 20 it, through a cavity partly filled with air. species against 185.

Among many useful discussions, we note (p. 26) It is worthy of mention that the origin of the that dolomite is stated to be equally soluble with calcite


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in water, and that hence dolomite-masses are capable times more concerned with the decorative value of his of giving rise to typical karst-phenomena. It is periods than with their absolute truth; for instance,

he makes a point that we go to a gallery to see a observed (p. 195) that the air of caves is a remarkable

picture of a sunrise when we might see the sunrise conductor of electricity. The relation of typical karst

itself! forgetting that it is only the awakened eyes surfaces to the removal of forests is pointed out, and which can see at all. “I never see a sunset like that," French areas, cleared after the Revolution, are cited objected the critic to Turner ; “Don't you wish you a3 examples. The French causses, by-the bye, deserve ) could,” answered the artist.


However, putting aside the question of these rather longer mention, considering how accessible they

and graces,” Prof. Bailey's thesis is sound enough; now are from Millau, and how finely they illustrate

civilisation is dying and will die of its own selfthe author's thesis. But we welcome the use made of the “ dolinas " and "poljes," names that recall the produced poisons; it is only by the improbus labor

on the land that the human

seems able to fascination of the Slavonic east. The author's classi- | persist.

A. D. H. ficatory instinct introduces us also to marine erosion and to Fingal's Cave; to a glimpse of the fauna of Lecture Notes on Chemistry for Dental Students. By caves; and to caves as the haunt of early man. But

Dr. H. Carlton Smith. Pp. viii +273. (New York:

John Wiley and Sons; London : Chapman and Hall, it is the treatment of the karst-phenomena that will

Ltd., 1906.) Price 1os. 6d. net. probably give this book a place among works of reference, although precise references to original The connection between dentistry and chemistry is

a two-fold one. The practical dental surgeon is a papers are rare in it, and although it has, strange to

worker in metals; he has to prepare amalgams for say, no index.

G. A. J. C. stoppings and carry out a multitude of similar oper

ations; hence his need for a knowledge of inorganic chemistry. No less important is the second link; he

must know the composition of the teeth, the action OUR BOOK SHELF.

upon them of the reagents and drugs he employs; he The Outlook to Nature. By L. H. Bailey. Pp. ix+ must understand the action of ferments, whether they

296. (New York: The Macmillan Company; are contained within the micro-organisms of the London: Macmillan and Co., Ltd., 1905.) Price mouth or in the secretions, like saliva, which come js. net.

in contact with the teeth; hence his need for a knowPROF. Bailey is well known as one of the most fertile ledge of organic, and especially of physiological

, and inspiring of teachers of science as applied to

chemistry. Dr. Smith has produced a work which agriculture and particularly to horticulture, who has supplies such needs, and one is glad to see he has built up a great school at Cornell and has also been provided an over-supply; for instance, the sections on the source of a wave of teaching froni nature among saliva, though naturally this subject is treated with

physiological chemistry do not deal exclusively with the schools of the United States.

In all Prof. Bailey's work may be seen the qualities special fulness. This is as it should be; the less of the enthusiast, who is moved, and gets his power

specialised and narrow a dentist's education, the iu move his followers, by considerations other than

more is he likely to benefit those under his care. those which are the ostensible object of his work.

In the analyses given of the different parts of the The life of the country-side, farming and gardening, teeth; Dr. Smith states that enamel contains 3 per then, are to Prof. Bailey something more than a

cent. of organic matter. He does not allude to the scientific study or a means of earning a livelihood

work of Tomes, in which it was shown that enamel they are the great regenerating influences of modern

contains no organic matter at all, and what was life. He sees civilised existence getting every day formerly given as organic matter (by difference) is more complex, more noisy, more hurried, more exact really due to water. It is not a very important point, ing; nor in the interests of efficiency does he expect and possibly the author was not aware of Tomes's or desire any wholesale return to a more primitive

research on the question. mode of living. But what he does plead for is the * return to nature" in “our personal and private

A Study of the Sky. By Prof. Herbert A. Howe. hours" as a "means of restoring the proper balance

Pp. xii + 340. (London : Macmillan and Co., Ltd., and proportion in our lives.” The book consists of

1906.) Price 25. 6d. four lectures, delivered in Boston, on such topics as This is a cheap edition of a book that appeared the relation of country to city, the part that nature- originally several years ago. Written in attractive, teaching should play in school life and the organ- simple languảge, Prof. Howe's volume is just the isation of rural teaching generally, with a final essay work for those readers who, knowing little or nothing on the position of evolutionary conceptions with re- of the oldest of sciences, wish to become personally gard to religion.

acquainted with the wonders of the sky. We get a vivid and interesting presentment of the A very pleasing feature of this book is the way in opinions and convictions which have made Prof. Bailey which the reader is forced to observe and experiment a living force in American education; we see that for himself. Chapter i. gives a brief historical sketch the writer is a passionate lover of nature with a of astronomy, and is followed by five chapters dealing strain of the poet in him, but we do not always find with the constellations observable at various seasons, his treatment convincing. The book must be judged and their apparent diurnal and annual motions. Then as literature, and in literature neither the best of inten- come three chapters dealing with astronomers in tions nor the finest of emotions count unless you can general and particular, and their tools. A chapter on express them with something of the freshness and time and the method of keeping it is followed by five inevitability of a living thing; here we often find (xi.-xv.) chapters dealing seriatim with the members the thoughts and arguments of Thoreau, but without of the solar system. The concluding chapters discuss his clear-cut and startling intensity of expression. in a simple but instructive fashion comets and meteors, Prof. Bailey is rhetorical, and that means he is some- the fixed stars, and the nebulæ.






With regard to the first condition, all the factors are

known, and the necessary conditions can readily be cal[The Editor does not hold himself responsible for opinions culated by two independent methods, which, as it proved,

expressed by his correspondents. Neither can he undertake are strikingly verified by the actual results obtained. The to return, or to correspond with the writers of, rejected only pitfall is in the altogether exaggerater impression manuscripts intended for this or any other part of NATURE.

which is abroad as to the ease with which a high degree No notice is taken of anonymous communications.) of vacuum can be obtained by modern methods.

The third condition was realised by using the magnetic The Positive Charge carried by the a Particle. deviation of the a rays as a test for their charge. The Some time ago I made the suggestion in NATURE (March 9,

rays passed out of the capillary tube from a deposit of 1905) that the a particle was initially uncharged on expul

radium C at the far end. This was obtained by the use sion, and that it gained its charge subsequently by col

of the emanation from 30 mg. of radium. Conditions were lision with atoms in its path. I need only now repeat

arranged so that the rays were completely deviated under that the suggestion was based on the brilliant work o'

ordinary conditions, and with the magnetic field on did not Bragg in Australia, who showed that the a particle passes

succeed in escaping from the tube, and the experiment conthrough, rather than collides with, the atoms of solid or

sisted simply in re-examining the deviation in the highest gaseous matter in its path, and that whether uncharged

vacuum that could be produced.

Long series of negative results led to the refinement of or not initially, it must, equally with the atom struck,

each essential condition until it seemed no further improve. become charged positively after the encounter by the detachment of a negative electron.

ment was possible, and a wide margin or probability that

the essential conditions had been realised had been secured. Recently P. Ewers (Physikalische Zeitschrift, March 1).

A most unmistakable negative result was obtained. But using the a particles from polonium, attempted to put the

the next experiment intended to confirm this finally was view to an experimental test with negative results, and

as unmistakable a positive result as the other had been a concluded against the probability of the hypothesis. Bragg

negative one. In a partial vacuum the rays were completely (Phys. Zeit. July 1) has pointed out that Ewers's experi

deviated. In the highest vacuum the field made no perments by no means settle the question, and, indeed, he

ceptible difference. Between the two experiments there evidently considers it a question which cannot be settled

were two slight differences of conditions : (1) In the second experimentally. Certainly the requisite conditions to be

experiment the radio-active deposit had been heated in fulfilled for a positive result are so rigorous that no one

vacuo after removal of the emanation and disappearance could be certain they had been fulfilled, and it is impos

of radium A in order to remove a possible overlying film sible to disprove the view by negative result.

of condensed gas. (2) In the first experiment the emanation But is obvious that a positive result, that is,

had been left in the capillary 2 hours 25 minutes, in the actual isolation of the

particle in

the second 1 hour 30 minutes, the volume occupied by the charged state, would settle the question. This I have

emanation being less in the latter case. been fortunate enough to do, although only after a long

In a third experiment the heating of the radio-active experience of negative results where it might reasonably

surface was omitted, and the emanation was allowed to have been concluded the requisite conditions had been realised. “The best laid schemes of mice and men gang

act for only 45 minutes. The result was unequivocally

positive. aft a-gley.” A determining factor in the problem conditioning whether a positive or negative result is obtained

In a fourth experiment the film was heated, and the

emanation left in 1 hour 20 minutes, reproducing praccould not possibly have been foreseen, and it was only when

tically the conditions of the second experiment. Again the all hope of getting anything but a negative result had

result was positive, and the magnetic field produced no been abandoned, and what was intended to be a final

appreciable effect in a high vacuum. But this experiment experiment was being performed, that a slight change in

was continued for nearly two hours after the start, and at one of the factors happened to eliminate the disturbing

the end of the time the radiation, although, of course, cause, and I obtained the coveted positive result. The

much enfeebled, was quite intense enough for the purpose. precise nature of this disturbing influence is, perhaps, not

As time elapsed a change came over the experiment. Little yet fully demonstrated, although personally I think I now

by little, the rays began to be affected by the field. This hold the clue. But there is not the slightest doubt that

change was hastened by heating the active film in place the a particle initially expelled is not charged as the ex

in the high vacuum.

At the end the result was as periments given prove. The essential conditions are two. In the first place, the

equivocally negative, all the rays being deviated by the

field in the highest vacua, as at the start it had been a particle must be examined in a vacuum such that during

positive. its path it does not encounter a single gas molecule.

The clue, I think, is the change of the glass surface of Secondly, the layer of radio-active matter from which it is

the capillary, which it experiences under the excessive bomexpelled must not be more than one molecule thick, and

bardment to which it is exposed, and which is indicated must not be mixed with or overlaid by inactive matter. These conditions being fulfilled, the a particle will not

by the blackening of the glass. In the lead glass used it

was remarked independently that the darkening appeared to traverse a single atom after expulsion, and if uncharged initially must remain so. As a third condition, it is de

commence somewhat suddenly. At the conclusion of the

experiment it was always marked. But on cutting down sirable that the test for the charge shall be made on the

the capillary before the commencement in the three final particle during its flight. It is at least conceivable that

experiments with relatively short exposure to the emanation an uncharged a particle striking a plate will convey to it a positive charge if the electron detached from the uncharged experiment, when the pole pieces were removed to allow

the darkening 'had not commenced, whereas in the last a particle on impact has sufficient energy to escape the

the deposit to be heated in place it was noted that the plate.

darkening had begun. It can be imagined that the slightest The second condition is, as may be imagined, the

roughening of the surface is all that is necessary to cause a difficult one to make sure of. I hoped to secure it by using radium C as the source of the rays. The rate of

negative result. The whole series of experiments from

start to finish is explained if accompanying the darkening its disintegration is so rapid that there is only just the

of the glass there is also a slight roughening. Whether necessary time for an experiment to be carried out. Hence

this will prove sufficient to be within the range of the the actual number of atoms of the radio-active substance

microscope remains to be seen. is for radium C the minimum it is possible to employ. I hope to examine the hypothesis that the blackening Moreover, this number can readily be calculated, and since

of the glass is accompanied by the roughening of the sur. it is deposited from a gas uniformly on the exposed surface, face more in detail later. But whether this or some other not only can an experiment be devised so that the thickness

explanation proves correct there can, I think, be no doubt of the deposited layer fulfils the monomolecular condition,

about the conclusion that the a particle has been isolated but, what is equally important, it can be assumed with

under conditions in which it is not deviated by a magnetic reasonable certainty that the radio-active layer is not field, and, therefore, is not charged. The theoretical conseoverlaid or mixed with inactive matter.

quences of the discovery need not here be dealt with. Cer


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