« PreviousContinue »
passed over with brief mention, and a statement that they have not been long enough in use to enable an
opinion to be formed regarding their value. THE DRESSING OF MINERALS.
The treatment of the subject is divided into general
considerations; volumetric sizing; sorting and washThe Dressing of Minerals. By Prof. Henry Louis. irig; comminution; separation by specific gravity;
Pp. x+ 544. (London : Edward Arnold, 1909.) appliances depending essentially on vertical fall; jigs; Price 30s. net.
horizontal current separators; shaking tables; pneuTHE author says, in his preface :,
matic, magnetic, and electrostatic separation ; separa“ The object of the present work is to give an
tion by surface tension; accessory appliances and account of the theory and practice of the dressing of general construction of dressing works. minerals, which will, I hope, prove useful to the It is, perhaps, in the chapter on volumetric sizing miner or metallurgist who desires to understand the that the treatment of coal and ores together is most principles upon which this art is based, as also to the manufacturer who supplies the necessary appliances, objectionable. It is sometimes difficult to gather and above all to the student who is preparing for whether the machine spoken of is used for coal or either of the above professions.”. "I have disores, and although, of course, many of them could be regarded the time-honoured division which would used for both, there is a more or less clear line of make separate branches of the dressing of ores, and distinction between the two. To find a Wilfey impact the cleaning of coals."
described between the Klein
and The first impression produced on reading this state- Zimmer conveyor screen seems curious. Trommels ment. is that the new departure is warranted; that are said to be satisfactory to in-inch mesh. In the there are many points in common in the two branches, chapter on comminution such varying machines as and that the comparison of practice under the different rock breakers, rolls, Huntingdon mills, ball mills, conditions would be of an illuminating character. tube mills, and disintegrators have been dealt with all The further perusal of the book, however, seems too shortly. The Griffin mill is passed over in one hardly to bear out this promise, and the joint treat- paragraph, in which it is described as
" like the ment of the two branches rather tends to confusion, Huntingdon mill with a single large roller which is for the cleaning of coal involves the use of so many caused to revolve on its spindle by means of gearing,” methods that are inapplicable to ores and vice versa but the construction, mode of action, and causes of that, if the two branches are to be treated in the same crushing are so different in the two machines that the book, they should at least be dealt with under different Griffin certainly merits a fuller description. sections.
It seems questionable whether vanners should be inDifficulties, inherent to the method adopted of cluded under the title of shaking tables, and no dealing with the subject, are found throughout the distinction is made between the condition of a pulp book, and it is practically only in the chapter on adapted for a vanner and that for a shaking table, general construction of dressing works that any clear The number of discussions that have taken place, and differentiation between coal and ore dressing appears. tests that have been made to prove whether it is better It may be that the manufacturer should be acquainted to classify the pulp or not before treatment with the machines used in both classes of work, and vanners, do not appear to be mentioned, while an even that the student should acquire a knowledge of, authoritative pronouncement on the subject would and be able to draw comparisons between them, but have been of interest. that coal-miners should be called upon to study the The subject of pneumatic separation has been various forms of rock-breakers, stamps, and other treated more fully than it appears to deserve, and crushing mills and fine grinders seems unnecessary. machines described which have certainly not war
The bock is well written and interesting, more rarted their existence. Magnetic separation has also especially, perhaps, in those parts that deal with received a good deal of attention, and many machines theoretical considerations which relate to the con
are figured which are used both for strongly and struction of the machines. The designs of various feebly magnetic substances. machines are illustrated by excellent plates, and In dealing with separation by surface tension, the leading dimensions are often given, as well as the author says it is impossible to offer correct or satiscost of the machines and manufacturers' figures re- factory explanations of the observed phenomena. He, garding capacity. The latter are sometimes apt to however, presents an historical account of the debe high; for instance, it is stated on p. 140 that a velopment of the processes which depend upon this pair of Krom rolls 26 inches diameter by 15 inches face property, and briefly refers to several of the flotation will crush about two tons of average ore per hour to processes. He has, however, only described the about 30 mesh.
Elmore oil process and the Elmore vacuum process in Relatively little information, however, is given as to any detail, from which it would seem that, in his setting up machines, their adjustments or running, opinion, they only are worthy of consideration. The the general conditions that have to be fulfilled or the chapter on accessory appliances passes from tipplers general care of a dressing plant. Early forms of to various ore bin gates, then comes back to creepers, machines and historical references have received a and returns to various conveyors of the belt, bucket, good deal of attention, possibly more than they scraper, and screw types. Car and bucket elevators deserve, while in many cases modern forms have been and tailings-wheels are dealt with, as well as
feeders, and the chapter is finished with a few words day traffic with the searching demands that motu on weighing and sampling.
traffic makes on the surface of the road,
that a There is a great deal of varied information con- bituminous binding or matrix should be employed tained in the book, but it would have been better to He points out that so far, although this fact is full, confine the subject to one or other of the branches recognised, no scientific study has been made i referred to in the opening paragraph.
standardise the materials used, and the proportion and
quality of this material :DUSTLESS ROADS.
* Thus the matrix is usually prepared as it seems
best to the individual in charge of the tar boiler wt.. Dustless Roads. Tar Macadam : A Practical Treatise uses anything that comes from the local gas works;
for Engineers, Surveyors, and Others. By T. who boils it as long as he thinks necessary, and adds Walker Smith. Pp. xi + 225. (London : Charles to it whatever he thinks may improve it in the way of Griffin and Co., Ltd., 1909.) Price 1os. 6d. net.
pitch or creosote. It is a subject in which the per
sonal factor has entered to an exceedingly great 'HE growing use of motor-cars, and the destruc- extent, and each man acts more or less as it seem,
tive action due to the rapid speed at which they best to him in his own mind.” are driven, and the sucking action of the indiarubber
The aggregates for tar macadam are also fully tyres on the surface of the roads, has rendered a
dealt with. The author points out that as the tar change in their management necessary. It is the almost unanimous opinion of road experts caused by friction in water-bound macadam is thus
binding cemeats the stones together, the abrasion that, in order to preserve the surface of the roads in absent, the properties of noiselessness, elasticity, and good condition, it is necessary that some kind of resilience being secured. The only portion of the road bituminous material must be used for binding the material which is subject to any considerable wear is stones of the macadamising, which, while cementing the surface, which has to bear the friction due to the them together, will also give a waterproof and com
rolling of the wheels, and also the impact of the paratively dustless surface.
horses' feet. It is, therefore, contended that the use The book under notice has, therefore, been pub- of granite or other similar expensive material is not lished at an opportune time, as the method of repair- necessary for the lower coat, which consists of from ing roads described in it, which has been more or less successful, has been
80 to 85 per cent. of the whole; but that where the so far only of a tentative
road is only subject to moderate traffic the lower layer character, the work not being carried out on any
may consist of hard limestone or slag, either of which scientific basis, but very much by the rule of thumb.
material holds the tar better than granite; the upper The author, who was borough engineer at Barrow- laver, which has to bear the surface wear and tear. in-Furness for several years, had under his charge being composed of granite. The author's experience many miles of macadamised roads subject to motor
leads him to the conclusiontraffic, and devoted his attention to experimenting and trying to find out the best means of solving the diffi
“that it is an absolute waste of money to put such cult problem of keeping these roads in good order, and good material as granite in the bottom when a less
costly material will do perfectly well when armoured preventing the creation and spreading of dust, at a
with a good coating of tarred granite." reasonable outlay. The results of his experience are given in the book under notice. The author, how- The patent processes known as “ Tarmac ” is deever, not content with his own experience, has also scribed. The makers of this road material have collected the opinions of a large number of road expended upwards of 20,000l. in the construction of surveyors throughout the country as to the advan- works and plants at Wolverhampton. The aggregate tages and disadvantages, and cost of tar macadam, used is slag, the tar is distilled before using, and the the answers to the queries submitted being given in mixing is done by machinery. The author, however, the tables contained in the book.
does not seem to think that it has any special advanThe subjects dealt with are divided into fifteen tage over ordinary tar macadam mixed locally when chapters relating to tar macadam as a remedy for dust
this is done in a proper manner. In the tables the nuisance; the necessity for standardisation in con- cost of the materials and of mixing and laying is struction; tar; aggregates for tar macadam; prepara- given for a great number of localities. As an average tion and laying; mechanical mixing; effect of wear this may be taken as from two shillings to half a and tear; scavenging, watering, and maintenance; crown per square yard for a coating of 31 inches o: camber, gradient, noiselessness, and hygienic advan- slag and hard limestone for the bottom layer, and half tages; tractive effort; statistics of road mileage; cost an inch of tarred granite for the surface coat. The of maintenance; and tar spraying. There are twenty- general opinion appears to be that there is a saving in four illustrations and a tabulated analysis of the the cost of maintenance of roads where tar macadam replies to queries.
is used in place of water-bound macadam, in some The author shows that the binding material used cases amounting to as much as 75 per cent., the in the making or repair of macadamised roads is the average, however, being put at 37per cent. crux of efficient road maintenance and the prevention With occasional tarring and sanding of the surface, of dust. His opinion is that it is absolutely necessary, a tar-macadam road, so far as the lower layer is if macadamised roads are to meet the needs of present concerned, is practically everlasting. The surface
where there is much traffic requires re-covering about sentations of important relations. Thus the complex once in four years. Instances are given from the quantity RC+ilpC may be laid down as a vector in author's own experience where roads having a fair a plane, RC being the component along a chosen amount of traffic “ have been as good at the end of direction and LPC the component at right angles to six years as when first covered, and so far as can be this direction, while the ratio LP/R measures the seen will need very little for another six years." tangent of the angle between the vector and the
This book ought to be carefully studied by all chosen direction of reference. Again, if we regard C surveyors having charge of roads subject to motor as a complete vector, the complex operator may be traffic.
considered to be a versor rotating C through the angle just named. Can utilise these fundamental
vectorial and versorial conceptions to construct a VECTORIAL GRAPHICS.
graphical representation of real value to the electrical l'ectors and l’ector Diagrams applied to the Alter engineer? The answer has been given in the affirmanating Current Circuit. By W. Cramp and C. F.
tive; and among those who have worked up the Smith. Pp. xvi + 252. (London : Longmans, Green method along these lines, no one holds a higher place and Co., 1909.) Price 7s. 6d. net.
than C. P. Steinmetz. The method has been preNOT many years ago a certain type of journalisi sented in more or less detail in most of the recent
used to compare and contrast the theorist and books on the alternating current, and now we have the practical man, to the demolition of the former
an extremely valuable addition to the literature of the and the apotheosis of the latter. Fortunately, such subject in “ Vectors and Vector Diagrams applied to an attitude of mind is no longer possible. The merely the Alternating Current Circuit,” the joint work of practical man could never have constructed the Forth William Cramp and Charles F. Smith, both lecturers Bridge, nor launched the Mauritania on her record in the electrical engineering school of Manchester making career. Innumerable examples might be University. The authors, for reasons given, depart given of the necessity of true theory in the economical somewhat from Steinmetz in their development of the designing of all kinds of machinery; but probably method, but the foundation is essentially the same. there is nothing that better proves how much mathe- Orce the fundamental propositions are admitted and matical science lies at the foundation of modern grasped, the whole treatment is a model of lucidity methods than electrical applications, especially those and self-consistency. One unusual feature of the that have to do with the alternating current. The book is that it assumes a certain fairly advanced whole history of the development of the transformer knowledge at the start. This is a good feature, which and the alternating-current motor is simply the might well characterise more of our text-books. The realisation of the solution of a differential equation authors are careful at the same time to indicate given long ago by Maxwell. In this realisation the exactly what knowledge the student must possess first great steps were taken by Heaviside, who in- before he is in a position to make effective use of their troduced the terms impedance, admittance, reluctance, | methods-he must know the fundamental laws of the &c., giving a new precision to the ideas involved. By alternating-current circuit very thoroughly. Neverthea mathematical extension of meaning the symbols less, it would have been of advantage to have indiwhich entered into the electrical equations of steady cated in a few preliminary sections the manner in currents became applicable to the corresponding cases which the method originally took shape as a synthesis of sinusoidal currents. Stated in purely mathematical of the symbolic solutions of Maxwell's differential language, this transition depended on the properties equations. There also seems to be a certain looseness of the complex variable.
of argument in the way in which the properties of Thus, to take the simplest case, Ohm's law RC=E vectors are stated. For example, having defined in for steady electromotive force becomes Maxwell's the usual geometrical way the meaning of the “ vector expression (R+Ld/dt)C=E when E is variable. product" of two vectors, and having so named it, Representing a sinusoidal electromotive by the ex- they remark, “ This product must itself be a vector ponential of the imaginary ipt, we get the solution in product, since it has already been shown to possess a the form (R+iLp)C=E, where C and E now stand definite sense.” This is no proof, but mere statement. for the amplitudes of the varying quantities. This | The defined product must be shown to obey the vector complex quantity which operates on C may be treated law of addition before it can be called a vector product. analytically like the real quantity R in Ohm's law. These imperfections do not, however, affect the Multiplication by the conjugate gives
purpose of the authors, who are to be congratulated (R? +L?p?)C=(R - iLp)E.
on having enriched our technical literature with a
clear and systematic exposition of the vectorial In the end, after all analytical transformations have graphics of alternating-current phenomena. After a been effected, the real part of the expression must be discussion of the more purely geometrical character of picked out. A little experience will make the average the method, illustrated throughout by reference to student quite efficient in this kind of algebra, familiar electrical phenomena, a succession of chapters especially if it is combined with numerical and follows on self and mutual induction, the transformer, practical work.
motors of the induction type, and alternating-current But the value of the method does not stop here. commutator motors. A chapter is then thrown in on Following familiar paths, we may give a geometrical the product of two vectors, and the two concluding form to the expressions, and obtain graphical repre- and longest chapters deal respectively with locus
diagrams and examples of the application of locus the convoluted tubule, the deduction is made that the diagrams. The book is amply illustrated by more functions of the latter are not the same throughcu: than a hundred diagrams. Everything is concise and its length. The facts adduced by these investigations to the point, and the student who works through its have very little bearing on the two rival theories of pages will find himself equipped with a valuable the manner in which the kidney removes the uring weapon of research.
from the blood-whether by a process of secretion or
one of filtration. THE RECONSTRUCTIONAL ANATOMY OF
The function of the narrow, clear part of the low THE KIDNEY.
of Henle is concluded to be the resorption of the wat: Untersuchungen über Bau und Entwickelung der is deduced from a ratio which Prof. Peter has found
which has been thrown out of the glomerulus. This Niere. Edited by Prof. Karl Peter. Erstes Heft. Inhalt I., Karl Peter, Die Nierenkanälchen des
to exist between the relative length of this part of the Menschen und einiger Säugetiere. II., Michio
tubule and the specific gravity of the urine in various Inouye, Die Nierenkanalchen des Rindes und des ruminants. In this matter his observations suppos:
mammalia with the exception of some of the smaile: Tümmlers. Pp. viii+ 447. (Jena : Gustav Fischer, the experiments of Ribbert and H. Marger, and of 1909.) Price 30 marks.
Hausmann. These experimenters removed the whole THE "HE editor of this monograph holds with Koelliker of one kidney and the medulla of the second in a
that a knowledge of the morphological character- rabbit, with the result that the urine was doubled CT istics of the renal tubules is an important groundwork trebled in amount. As the narrow, clear part of the for the study of the physiology and diseases of the loop of Henle is contained in the medulla, it is inkidney. This ground plan he has laid down in a bulky ferred that the increase in the amount of urine is due volume, profusely illustrated by numerous and well to the removal of the resorbing part of the tubule. S. executed drawings. By means of maceration with many factors have to be considered in a case like this concentrated hydrochloric acid and subsequent isola- that the author's deductions must be regarded with a tion of the urinary tubules, as well as by reconstruction certain amount of reserve. While one must adinire models and serial microscopic sections, he has studied, the industry and accuracy manifested by this work, along with his pupil, Michio Inouye, the structure of 1 it must also be admitted that even those specially the kidney in various mammalian families in great interested will find it very tedious reading, and it is detail. For the benefit of those who desire to ascer
to be hoped that it may be possible to confine the tain his results without reading the whole of the
other promised volumes within a more modest comtext, he condenses a summary of his work into
R. D. k. seventy-five pages of this volume. Prof. Peter has worked out the structure of the
GREEKS AND HITTITES. kidney of the mouse, rabbit, sheep, cat, man, and pig, while Inouye has studied the organ in the Ionia and the East. Six Lectures delivered before the seal and ox. They have given a minute description,
University of London by D. G. Hogarth.
Pp. 117 perhaps too minute, of the organ in the various
(Oxford : Clarendon Press, 1909.) Price 35. 6d. net. animals without adding, to any great extent, to our
'HE author of this book aims at solving the inknowledge of the subject.
teresting problem of the origin of Hellenic As a result of his study, Prof. Peter divides the civilisation in the Grecian colony of lonia, in western medulla of the kidney into an inner and an outer Asia Minor. He utilises, in a masterly manner, the zone, and the latter into an inner and an outer area. results of the extensive archæological researches that The cortex he divides into a pars convoluta and a
have been carried out within the last thirty years in
Schlie. pars radiata. These, to some extent, can be recog- south-eastern Europe. The excavations of nised with the unaided eye or by means of a lens, and
mann, Evans, and numerous other workers in this each is composed of certain definite parts of the field have completely revolutionised our ideas about tubules, each zone or area being composed of the same the origin of that early Grecian culture to which parts in the same species. In fact, with some slight modern European civilisation owes so much. exceptions they are composed of the same parts Mr. Hogarth's conclusions are, that in Attica the throughout the whole of the mammalia. A summary home country of the Ionians, the population, before of the zones and their contents is given.
the migration 10 Asia Minor, was mainly Ægean, but These researches of Prof. Peter--minute and mixed with a northern element of invaders from the accurate as they are—have particularly little in them
Danubian area. At this date there survived in Attica that will interest those who seek to elucidate the a vigorous bloom of Ægean culture affected to an functions and diseases of the kidneys. The author unusual degree by some eastern influence, so that himself states that as regards the significance of the the colonists who settled on the west coast of Asia Malpighian bodies his investigations have produced Minor in the early centuries of the first millennium B.C. nothing new. Concerning the first convoluted and were by no means barbarians. In lonia the Greek zigzag tubules which he includes under the name of settlers came in contact with a highly developed the “ Hauptstück," certain observations have been Asiatic civilisation--namely, that of the Hittitesmand recorded with regard to variations in the amount of one of the most original features of Mr. Hogarth's fat contained in the cells, and from the fact that these book is the demonstration which he gives of the powervary in their affinity for eosin in different parts of ful influence of the Hittite civilisation in the develop
ment of the Hellenic culture in Ionia. The Hittites delightful simplicity and freshness of their style, and were predominant in Asia Minor from 2000 B.c. to by the variety and ingenuity of the experimental 800 B.C., and, besides being possessed of a highly illustrations, but more especially with the completedeveloped culture of their own, acted as intermediaries ness of the story he had to tell. There is little that for the transmission of Mesopotamian culture to the has been modified or extended in this branch of knowGreeks. Of both these influences there is distinct ledge during these fifty years; there is scarcely a evidence in the few excavations that have been carried single sentence which might not be uttered without out in Asiatic Greece.
comment or correction to a similar audience to-day. There appears to be a rich field awaiting the It is not surprising, therefore, that a fresh edition archæological excavator both in Ionia and in other of Dr. Meyer's excellent German translation should parts of Asia Minor. In Lydia, which was apparently be in demand among young people in Germany, a Hittite satrapy, very little excavation has been done, and it speaks well for their appreciation of Faraday and in the Hittite country on the upper Euphrates and his charming "chemical history” that the transhundreds of buried cities are known to exist, in some lation has reached its fifth edition. of which, it is almost certain, as Mr. Hogarth points The book is attractively bound, and contains a very out, bilingual inscriptions connecting the Hittite script pleasing portrait of the author, together with a short with the Assyrian will be found. We may, then, expect biography. discoveries equalling, if not excelling, in importance (2) Mr. Adie justifies the production of another those that have recently been made in Mesopotamia, elementary chemistry on the ground that the average in Egypt, and in Crete.
first-year student shows a lack of intelligent underAnother iconoclastic view of Mr. Hogarth's is that standing of chemical aims and methods, for which, the Phænicians played an insignificant part in the we infer, the other books are mainly responsible. We development of Greek civilisation. He reduces “the are inclined to think that this want of intelligent part played by the Phænicians among the Greek understanding is due neither to the character of a Isles and coasts to that of mere huckstering traders particular book, nor altogether to the teacher, but to who followed seaways long ago opened by others.” the kind of chemistry done in schools and fostered by
Mr. Hogarth considers that the Hittites were not the scholarship system of the older universities. a maritime people, but were confined strictly to their If the systematic study of chemistry at the unicontinent by the Ægean command of the sea. In versity or college were founded on a good general view of the migration from Lydia to Umbria related knowledge of mechanics and physics, and an eleby Herodotus, and of the existing population of broad-mentary notion of those chemical processes applicable headed races in the Balkans, which, judging from to everyday phenomena, the path of the college proits present distribution, must apparently have landed fessor or lecturer would be made much smoother. on the eastern shores of the Adriatic, Mr. Hogarth's But schools not content with this modest views on the non-mar ne character of the Hittites programme, and insist upon a standard of knowledge will, we venture to think, be considerably modified by beyond the grasp of the average schoolboy.
The future discoveries. The one weak point in Mr. result is that the college teacher has to build upon a Hogarth's admirable little book is his disregard of muddy foundation of confused ideas, which are the evidence of physical anthropology. No explana- familiar to examiners and so difficult to eradicate tion of the ethnological evolution of the East will be later. What commends Mr. Adie's new book is not satisfactory which fails to account for the transition so much the disastrous effects of its predecessors as of the primitive dolichocephalic peoples of the Balkan the long teaching experience of the author.
The peninsula into the strongly brachycephalic population results of fifteen years' experience of a thoughtful of the present day, and in this respect Mr. Hogarth's teacher are always valuable, and, as one might have otherwise admirable work completely fails. J. G. anticipated, the book offers a thoroughly sound course
of practical instruction.
The arrangement of the exercises is clear and SOME NEW CHEMICAL BOOKS.
logical, the examples are thoroughly typical, well (1) Naturgeschichte einer Kerze von Michael Faraday. selected, well illustrated, and carefully described.
Herausgegeben von Dr. R. Meyer. Pp. viii + 172. Many of the experiments, without being exactly new, (Leipzig : Quelle und Meyer, 1909.) Price 2.50
are modified and arranged in a convenient form, and marks.
the quantitative examples, which are numerous and (2) Junior Chemistry. By R. H. Adie. Pp. viii +
varied, furnish a sound basis for that most difficult 266. (Cambridge: University Tutorial Press, 1909.) part of chemistry, the understanding of quantitative Price 2s, (d.
laws and the theories drawn from them. In reference (3) Chemistry. By Prof. W. A. Tilden, F.R.S.
to the quantitative part, it would be interesting to Dent's Scientific Primers. Pp. ix + 108. (London : know what sort of errors the author obtained in J. M. Dent and Co., n.d.) Price is. net.
determining such things as the gravimetric composi(1)
of a candle were, it may be remembered, of the oxides of nitrogen, of which no actual examples delivered to a juvenile audience at the Royal Institu- are given. If the two oxides of nitrogen give anytion during the Christmas holidays of 1860-1, nearly thing like correct results by the method described, that half a century ago.
much-quoted example of multiple proportion would In reading them we are impressed not merely by the | lcse something of its elusive character.