rmany, that influenza may occur sometimes as an arently primary pneumonia. The remaining tables deal with the data afforded by epidemics of 1891 and 1892 in this country and road. That of 1891 is shown to have been much more al, especially at advanced periods of life, than that of , while that of 1892, here treated of with less fulness in the preceding, seems to have been of still greater erity. Those who would follow Dr. Dixey into the tails of these outbreaks must study the work for themves. It is a contribution to statistical literature of ry great value, and will save an infinity of labour to ase engaged in the study of influenza. A word of praise must be bestowed in conclusion upon e graphic charts with which the tables have been ustrated, those in particular which deal with the ortality curves from influenza and its allied diseases. hese have been calculated and mapped out as perentage deviations from the mean, and show the main acts at a glance in a way which mere columns of figures il to do. Those also which illustrate the age incidence f the diseases in question are of great value. OUR BOOK SHELF. An Elementary Text-Book of Hygiene. By H. Rowland Wakefield. (London: Blackie and Son, 1892.) THE appearance of yet another elementary text-book upon the subject of Hygiene has the effect of aggravating the embarras de richesses which already obtains in this department of study; one is therefore justified in questioning the utility of the present volume, and on reading in the preface that it is adapted to the requirements of the Science and Art Department, there is all the more matter for surprise at its appearance in the face of three other publications-each better than the present-which have been written to meet the same end. The manual is well printed and concisely written, and a surprising amount of matter is condensed within its tiny compass. This latter fact, however, is not entirely a matter for congratulation, for apart from making the book "dry reading," it must have the effect of rendering it in many places difficult of comprehension to those for whom it is intended, .e. those who approach the subject with no prior knowledge whatever. And thus it comes about, that in less than 200 small pages the whole range of Hygiene is surveyed, including chapters upon Eyes and Sight, School Hygiene, House Sanitation, Personal Hygiene, Parasites, Infectious Diseases, Accidents and Injuries. Though the material given has been on the whole well selected and carefully compiled, the work is a little uneven; one finds seventy-three pages devoted to "food," whereas "water" is dismissed in seventeen, and "sewage and its removal" in eleven. Here and there is evidence of the fact that the author is not of the profession to which Hygiene holds a filial relation, and that he was not quite at home with some of the departments of the subject-even in their elementary form-which he had set himself the task of handling; the very few errors and ambiguities which this fact is accountable for, are, however, too trivial to much affect the general accuracy of the book. The small work will doubtless suffice for the examina tion requirements of those for whom it is intended, but the brevity and superficiality of treatment which is so frequently apparent within its pages, will not justify one in recommending it to those who wish to lay a good and useful foundation for a study of the science of Hygiene. Ostwald's Klassiker der Exakten Wissenschaften. Nos. 38-40. (Leipzig: W. Engelmann.) WE are glad to note the addition of three volumes to this admirable series. No. 38 is the second part of the original account of the photochemical researches of R. Bunsen and H. E. Roscoe (1855-59). The other volumes are translations of a paper by Pasteur on the minute organic bodies in the atmosphere (1862), and of papers by Lavoisier and Laplace on heat (1780 and 1784). In all the volumes there are figures in the text. LETTERS TO THE EDITOR. [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.] Geographical Names. As the names of places given to the public with the authority of the Geographical Society of London are very apt to be accepted by geographers and be ultimately inserted in atlases and works on geography, I have to call attention to the paragraph Nomenclature of the Karakoram Peaks," under "Geographical Notes," p. 857, in the December number of the Proceedings of the R.G.S., 1892, which I have lately read. It is to be regretted that so much reliance and importance has been placed on what a native drew on the sand, and the names he gave to various peaks. Natives are not always to be depended upon, not even when the topographical features are in sight, and unless verified from other and independent informa ion, the names they give cannot be implicitly trusted and placed on record, as is so well exemplified in this case. The traveller must also have a considerable knowledge of the native languages or he may be very much misled. As fortunately I know both the places bearing the names given for two very conspicuous peaks, it may not be too late to prevent these names thus put forward from being accepted and perpetuated. "Skeenmung or Skinmang is the name of a comparatively level piece of somewhat grassy ground at the great bifurcation of the Punmah Glacier, the name itself is expressive and is derived from "Skeen" an ibex, and Mang, a level place in Balti= Marg, Kashmiri, Maidan Hindustani-which disposes of it as a likely designation for a peak. Next we have " Chiring" given as the name of K2, the second highest peak in the Himalayas, quite as inaccurate, for it happens to be the name of another camping spot or bivouac at the end of a spur and about halfway between Skeenmang and the Mustakh pass, as used about the period I was there (1860). It is situated just above a very narrow part of the glacier, where Chirna" in its action is most marked on the rocky sides. Hindustani is to rend, tear, and Chiring Gause is the name of all that portion extending six miles up to the main watershed. H. H. GODWIN-AUSTEN. Shalford Park, Guildford, January 7. The Weather of Summer. THE number of days with rain, in summer, at Greenwich, during most of this century, has been subject to a pretty regular fluctuation. The curve (from 1825) having been smoothed by means of five-year averages, we obtain that shown in the diagram. And putting with it a curve of sun-spots, we find a strikingly definite correspondence (somewhat "lagging" in character) throughout at least four of the sun-spot cycles, the rain day maxima coming soon after the sun-spot maxima, and rain day minima soon after sun-spot minima. In recent years, however, the curves appear to have got out of step (so to speak) with each other; so that, e.g. we find a rain day maximum in 1880, two years after the sun-spot minimum of 1878, and a rain day minimum in 1885, two years after the sun-spot maximum of 1883. I do not remember to have seen the facts of our summer weather put in this way. But it is well known that, in the discussions which arose some time ago about sun-spots and rainfall, there appeared some reason to believe that in the period of those four earlier sun-spot cycles, at least, we had had, on the whole, wetter years about sun-spot maxima than about the minima. A good deal was written on the subject (as your own columns show) in the seventies; and the data used seem to have been generally those of annual rainfall. Of late, apparently, the matter has attracted less notice; for the reason (I suppose) that the correspondence referred to has not been maintained, and recent facts have seemed rather against the theory of a causal relation between the two orders of phenomena. Thus the teaching of the curve here given appears to harmonize, in general, with known facts about annual rainfall. I do not propose to try and weigh the data so far as they may be considered to favour the theory just indicated (earlier and greater part of the curve), nor the data which may be considered adverse (in the short, later part). It seems to me that the curve may be usefully studied per se, apart from any relation to sunspots. Thus we might note the fact that all those maxima where our summers have got to a turning point from wet to dry have been quite near the beginnings of the decades. The dates are 1830, 1839, 1850, 1861, and 1880. The curve ends at 1890 (the final point representing, of course, 1888-92), and the position of this point, together with the date, seem to warrant our looking for an early descent of the curve, and a commencing series of (on the average) drier summers than we have had lately. We might also note that the minima of the curve have ranged from the fives to the eights. Thus we have, 1827, 1835, 1845, 1857, 1868, 1885. Should the recurrence continue, we might look for the next minimum about 1895-1898. Of course there may be difference of opinion as to the strength of the presumption here afforded for such a forecast, and no good reason is offered (beyond experience) why the curve should now take the course roughly indicated. It is not at variance with the above view that there is reason, it would appear, to anticipate soon a series of wetter years. In an article contributed to the Times of October 22 last year (cited in NATURE, vol. xliv. p. 630) Mr. Symons says: "There is no doubt that since 1887, at all events, the rainfall over England has been much below the average; and a consideration of all the facts leads to the conclusion that such a period of scarcity is very likely to be followed by one of abundance, and that the coming few years will probably be more rainy than those recently experienced, although possibly the increase will not occur in the summer months-at a time when it would be most noticed." A. B. M. "Aminol." My attention has only now been called to the letter of Dr. Klein, which appeared in NATURE, ante, p. 149. To the remarks referring to "Aminol" (with Periodate I am in no way concerned) I desire, with your kind permission, to make the following reply, as they contain inaccuracies which, if not corrected, must do me injury. The samples of "Aminol" alluded to by Dr. Klein were sent by me to a number of medical practitioners who had kindly consented to give it a trial. The strength of the samples was I in 5000. Dr. Klein has carried out between September, 18, March, 1891, five separate consecutive series of exper with "Aminol," with the object of testing its applicabil the treatment of certain external disease processes. H sults are recorded in a report, the summary and conclusio which were publi-hed last year with his full approval strength of solution employed in the first four series (which only of a tentative nature with a view to arrive at a p strength of solution for practical application) was 1 in 6000 the fifth series a solution of the strength of 1 in 600 was Dr. Klein's letter leads one to suppose that he operan with the latter strength. The pathogenic germs selected for testing the powere disinfectant were spores of Bacillus anthracis, sp Bacillus anthracis, Staphylococcus aureus, Bacillus diphi and Streptococcus erysipelatis. Amongst the results c with the solution of the strength of 1 in 6000 his repor tions the following: In Series IV., "On Staphylococcus au which may be taken as the most resistant microbe my those associated with surgical and other external disease cesses, the "Aminol" solution (1 in 6000) did produ effect, though a limited one, after two hours already, and t twenty-four hours destroyed the microbes." In Ser. "Aminol' solution (1 in 6000) kills the Bacillus diphther two hours. This was confirmed in Series III." In the nection it deserves to be noted that I possess already evidence, which will be published in due course, of consp successes obtained in practice not only with the solutions: strength of 1 in 5000, but also with dilutions of the same to I in 20,000. Dr. Klein's statement of the results which he obtained "Aminol" in the strength of 1 in 600 is misleading. Hes "Spores of Anthrax bacilli remained unaffected after hours, only after an exposure of twenty-four hours 2 number of living spores decrease; but some escaped d tion even after so long an exposure. Now what are the I quote from Dr. Klein's report: "Spores of Bacillus anthracis after good growe "Spores of Bacillus anthracis after growth 24 hours from 100 Is it putting the case fairly or even clearly, seeing that 30 ́s were made between twelve and twenty-four hours, "only after twenty-four hours did the number dec and seeing that only 6 per cent. remained after twa hours? Is not that a decrease practically amount disinfection? Would it be extravagant to assume that th significant percentage remaining would be eliminated a very little longer exposure (say another hour), and is the doubt that a solution of the strength of 1 in 500 or 12. would have accomplished complete disinfection in a much s time than twenty-four hours? But in order to illustrate th nificance of the results actually obtained with this solution strength of 1 in 600, let us see which other disinfectants anthrax spores in twenty-four hours. I quote from "Ex Disinfection," abstracted and translated by Whitele lished by the New Sydenham Society: (1) "For practical purposes a disinfectant should not much longer than twenty-four hours." (2) "Except chlorine, bromine, and iodine, only chloride, osmic acid, and potassic permanganate (5 per destroyed anthrax spores within twenty-four hours. Since cent. solution of permanganate is inadmissible for disse in bulk, and osmic acid is out of the question, we have mercuric chloride and iodine, bromine, and chlorine." The strengths in which the above-named substances in destroying anthrax spores in twenty-four hours are Koch's tables thus : Permanganate, aqueous solution 5 per cent (1 in x Iodine Mercuric chloride Osmic acid 2 1 per cent (1 in 13 (1 in 100 Now put against this the fact, quoted above, that Dr. Ke "that Aminol,' strength 1 in 600, killed 94 per cent. of spores in twenty-four hours," and further (I am qu report again), "that this solution is a perfectly harmles regards the human organism; therefore no undesirable d could ensue owing to its being absorbed; this is well wn to be the fact with some antiseptics, as in carbolic acid ications or in the use of perchloride of mercury.' oes not all this clearly establish the claim of "Aminol" to alled not only a true disinfectant, but a most potent and a safe one at the same time? at with all this (I mean what relates to its effect on anthrax es) its application in medical and surgical practice has ing to do, unless it be to demonstrate its comparative poy, for, as Dr. Klein himself points out in his report, "The es of Bacillus anthracis may be left out of consideration, as do not occur in the living body; under these conditions the illus anthracis is always sporeless; a malignant carbuncle of skin contains the Bacillus anthracis only in the sporeless and in infection with anthrax generally the bacilli are ys in the sporefree state both in the blood and in the es. hat is of real importance in practice is the effect of "Amion the other pathogenic germs on which Dr. Klein has d it. And here again his letter states the case in a manner his apt to mislead : "Anthrax bacilli, Staphylococcus s and others were destroyed, but only after a lengthy exre." ow what does his report say? "Series V. From this series ill be seen, therefore, that the solution used in the same 1600) acted very differently from that used in the previous eriments (1 in 6000) inasmuch as the Staphylococcus aureus, ch was not killed heretofore in eight hours, was in this ince completely disinfected in that time, and was consider'reduced even in one hour. The sporeless Bacillus anthracis, illus diphtheria, and Streptococcus erysipelatis were killed in hour." Can it be fairly said, then, that these were killed after lengthy exposure, and does the word "only" apply at all he one-hour results, when it is considered that there was no made under the one hour? What is there to show that those which there was no growth after one hour's exposure to the afectant had not been killed after ten minutes already? oes it not look, then, as if Dr. Klein had penned his letter hout consulting either his notes or his report? word in conclusion. Dr. Klein, for whom perhaps nobody rtains a higher personal regard than myself, may rest assured the designation," a true disinfectant," is meant by me to y only to such strengths of solutions of "Aminol as can pete with those substances and their respective strengths to h Koch has accorded that appellation. Nor need he to ehend that anything has been or will ever be done by me itionally committing him to what is not fully warranted ais actual results as recorded in his authorized published HUGO WOLLHEIM. rt. >1, Leadenhall Street, E. C., January 2. HE point at issue between Mr. Wollheim and myself is a ✓ simple one, and needs no long explanation on behalf of Wollheim. As you will see from the letter which you lly printed in NATURE, ante, p. 149, Mr. Wollheim, withmy authority, has sent round a leaflet with my name on it, mpanying bottles of "Aminol," stated to be "a true fectant.' On this leaflet my name is introduced in a somewhat mising manner, for it quotes to a large extent from my reports he lime and brine experiments on microbes without saying ut leaving the reader to infer that these reports of mine to "Aminol." Mr. Wollheim never asked my permission or informed me is intention of sending with each sample bottle of "Amisuch a leaflet. It is unnecessary to say that had he d me whether he could use my name on a wrapper of a at medicine I should have emphatically answered no. as recently informed me that he has cancelled the leaflet. The samples of "Aminol" sent out were of the strength in 5000, the experiments in which I showed that "Ami possesses a certain disinfecting power were made with a gth of 1 in 600. This strength did not kill spores of ax in 12 hours; 1 in 6000 did not kill Staphylococcus in 8 hours. Substance which, like the "Aminol" sent out (viz. I in , cannot kill Staphylococcus aureus in 8 hours, and has cally no effect on spores of Bacillus anthracis cannot be dered "a true disinfectant." show that Mr. Wollheim had a very strange idea about the whole matter, one has only to compare the actual facts of the case, as regards "Aminol" of the strength of I in 5000, with the motto put on the leaflet and the inscription on the label of the samples. For Mr. Wollheim quotes Koch to the effect that no disinfectant can be called a true disinfectant that does not kill spores, and notwithstanding that I have shown that "Aminol" even of the strength of I in 600 cannot kill spores in 12 hours, yet Mr. Wollheim advertises the "Aminol" of the strength of 1 in 5000 as "a true disinfectant." A true disinfectant kills spores after short exposure; a substance that requires many hours to do so cannot claim the name of a specific disinfectant. Vinegar, dilute acids, alkalies, and a host of substances affect spores after exposure for many hours (8, 12, and 24 hours), yet no one would consider these substances as specific disinfectants. Again, a substance used in a certain strength (say I in 600) may have considerable disinfecting power on non-spore bearing microbes, with or without having any conspicuous action on spores. The same substance more diluted (say I in 5000) may have retained such action only to a very insignificant degree. Take for instance perchloride of mercury; while this substance is a powerful disinfectant when used in the strength of I in 500, I in 1000, even I in 2000, it has greatly less effect when used in more increased dilution. No one is justified in advertising perchloride of mercury of the strength of 1 in 100,000 as a true disinfectant," knowing that I in 500 or 1 in 1000 only can be so called. How much more does this hold good for a substance like "Aminol," which even in the strength of I in 600 does not kill the spores of anthrax in 12 hours, a period which for practical purposes of disinfection is out of the question. E. KLEIN. 19, Earl's Court Square, S. W., January 9. Super-abundant Rain. IN NATURE of November 10 the fact that "very nearly onethird" of the annual rainfall fell in one month at Nant-y-Glyn, in North Wales, is recorded as "remarkable." But at Peshawar, on the north-west frontier of India, we received during last August a rainfall of 17.75 inches, the average local annual fall, calculated from the last fifteen years, being 13'51 inches. We therefore had very nearly sixteen months fall in one month, and by far the largest portion of this fell in ten days of the month. I need hardly add that the whole valley was flooded, and that we have since paid for our super-abundant rain in the form of very prevalent and fatal malarious fever. H. COLLETT. Peshawar, December 19, 1892. Earthquake Shocks. THERE were two unmistakable shocks of earthquake on the afternoon of Tuesday, January 3, the first at 2h. 15m. 15s. G.M.T., and the second at 2h. 17m. I was sitting in a railway carriage at Severn Junction Station waiting for the Bristol passengers, when I felt a sensible upward movement of the seat (as if pushed from below) and saw the carriage sway. The movement was from south to north (i.e. at right angles to the railway). This was repeated four times in about six seconds. At 2h. 17m. there were two more (less strong) shocks. The carriage was placed in a siding, and there was no train at the station, and the air was calm and frosty. Ice was said to have E. J. LOWE. cracked near here at this time. Shirenewton Hall, Chepstow. A Brilliant Meteor. ON Wednesday, January 7, at about 6.35 p.m., I was fortunate enough to see a brilliant meteor descending a little north of Castor. My attention was drawn to it by the brilliant light it threw over the country. The head was a ball of dazzling white and the tail yellow, with red streaks. It disappeared before reaching the earth, and I heard no report or rushing sound whatever. As the duration was only a few seconds the above are more impressions than observations. W. POLLARD. Pirton, Herts, January 7. CHEMICAL SOCIETY'S MEMORIAL LECTURES. ATM T an extra meeting of the Chemical Society, held on December 13 last, this being the first anniversary of the death of Stas, a paper was read and discussed which had been prepared for the occasion by Prof. J. W. Mallet, F.R.S., of the University of Virginia, U.S.N.A. -himself a high authority on atomic weight determinations, and well known to chemists through his papers on the atomic weights of aluminium and gold, published by the Royal Society of London. The lecture marks a new departure in the work of the society. Hitherto our learned societies have been in the habit of publishing more or less complete-it would probably be nearer the truth to say incomplete obituary notices of their foreign members. The Chemical Society has come to the conclusion, however, that inasmuch as its foreign members are always men of great distinction who, as a rule, have lived a considerable number of years after accomplishing their life work, it will be to the advantage of its fellows and of chemists generally, if the obituary notices of foreign members take the form of critical monographs of the subjects with which they have principally dealt. The anniversary of the death of the foreign member is obviously the most appropriate occasion for the delivery of such a lecture. During the past year the society has lost two of its foreign members: Hermann Kopp, noted as an historian, as well as on account of his very numerous exact determinations of atomic volumes and specific heats, and A. W. von Hofmann. The life and work of the first mentioned will form the subject of a lecture to be delivered on February 20 next, by Prof. Thorpe, the Treasurer of the Society, than whom no one is more qualified to undertake the task. Prof. Thorpe is not only a pupil of the deceased chemist, but has reverently followed in his footsteps-having very largely extended Kopp's observations on atomic volumes in an elaborate investigation, the importance of which was recognised by the Chemical Society in 1881 through the award to him of its first Longstaff medal. Von Hofmann, although originally a foreign member, became an ordinary member of the Chemical Society on coming to England as professor at the school in Oxford Street, long since merged in what is now known as the Royal College of Science, London. Hofmann was never again regarded as a foreigner; he served the society both as foreign secretary and as president, filling one of the vice-chairs during the remainder of his life. It is felt that owing to the special nature of his relations to the society and to english chemistry, it will be necessary to deal with his case in an exceptional manner; it is therefore hoped that in May next Lord Playfair-who was so intimately connected in his early days with chemical science and with the society-in the first place will picture the state of affairs chemical at and prior to the time of Hofmann's arrival in England. Sir F. Abel, Hofmann's first pupil and assistant, will follow with an account of Hofmann at the Royal College of Chemistry, calling to his aid for this purpose the remaining friends and pupils of Hofmann. The coal-tar colour industry, which has now attained such important dimensions, it is well known, had its origin in the Oxford Street laboratory, and Dr. Perkin-its parent-has consented to sketch the history of its development. In this manner it is hoped to impart considerable "local colour" to the Hofmann memorial lecture, thereby distinguishing it from the notice which is being prepared by the German biographers. Passing now to Prof. Mallet's lecture on Stas, which is of considerable length, as it will occupy fully sixty pages in the Society's Journal. The biographical portion is brief, as a number of such sketches have already been published. Stas was born at Louvain on August 21 He graduated as Doctor of Medicine. His task chemical research was evidenced in 1835, when, to with a friend, be investigated in an attic of his fa house the crystalline substance phloridzin which the extracted from the root bark of the apple tree. He tinued the study of this substance in Dumas' labor. in Paris, and it is an interesting proof of the acu Berzelius that in his annual report on the prot chemistry he referred to this first research made t with praise, and a prediction of future eminence for author. The starting-point of the long train of research which his name will ever be associated was the re mination of the atomic mass of carbon which Dun he together undertook, in order to explain the noticed by Liebig and others, that the sum of the ar and hydrogen found in hydrocarbons by the com process, as calculated from the carbon dioxide and not unfrequently exceeded the quantity of materia lyzed. As the result of this investigation, whic carried out with unprecedented care and the s borate precautions, the value hitherto accepted for t on the authority of Berzelius (76432 0=100) W siderably reduced (to 75 005). In 1840 Stas was ap Professor in the Ecole Royale Militaire at Bruss held this post for more than a quarter of a century an affection of the bronchial tubes and larynx him to give up lecturing. He then received an 30 ment in the Mint, but resigned this in 1872 on p grounds, and withdrew into private life. He to have been a man of great independence of char Apart from his atomic weight investigations St much work of value in other departments. His re of separating alkaloids from organic messes-?? name is applicable-which has been of such servi subsequent toxicological inquiries, was devised in in the course of the inquiry into the celebrated Be nicotine poisoning case. He examined into the meth hydrolysing fats for the purpose of a report t chemical section of the London 1862 Exhibition. E nection with the preparation of international star he took an active part, along with Devile, in the into the properties of the platinum metals. It is also that he did important work for his Governme investigating alloys for use in the construction of ar Prof. Mallet prefaces his account of Stas's specia vestigations by an historical survey of the fundam ideas which have gradually led up to the question, is the mass of an atom of a particular element in and beyond the days of Cavendish and Prieste fact that atmospheric air was found of constant of 20 constant composition was long a stumbling-block way of clear distinction between a homogeneous pound and a uniform mixture. To the labours Helmont, Boyle, and Boerhave much credit is due f gradual advance towards the doctrine of the conserv of matter. The discoveries of Black and Cave brought it further into view, and it assumed its due ance and began to receive universal recognition constant appeal to the balance which Lavoisier ma. taught others to make. Next came a comparison quantities of different substances, at first chiefly e known acids and bases, which would enter into tion with each other. Proust, in the course of b troversy with Berthollet as to the fixedness of cont proportions, had observed that in certain cases it w that in different compounds, consisting of the same stituents, for a fixed quantity of one constitut different quantities of another constituent beart other a simple multiple or sub-multiple relation Dalton, however, belongs the honour of announc principle as a general one, and of basing upon it 1 chemical atomic theory of the nature of matter. Be he early years of the present century, with apparatus any respects inferior to that of the present day, and scarcely any aid from chemical manufacturers in paring pure materials and reagents, but with unsursed manipulative skill and the most honest criticism is own work, produced the first fairly trustworthy of numbers representing the proportions by weight which the elements combine. Berzelius began work his direction in 1807, his attention having been acted by Richter's investigations; but soon afteris he became acquainted with Dalton's new atomic ry of the nature of combination, and appears to have 1 impressed with its great importance, and at the e time with the need of more exact experimental 1 for its support and development. The wonderful iracy of Berzelius's work generally is illustrated, as f. Mallet points out, by the fact that his number for gen, 16:021, becomes 15.894, almost exactly agreeing the latest determinations of the present day, if the ghings of Dulong and Berzelius's three experiments on synthesis of water be corrected for the buoyancy the air. Since Berzelius many other chemists have ked in the same field, but his most worthy successor uch labours has undoubtedly been Stas. With greatly ter resources in the way both of apparatus and material, n equal earnestness in seeking for the truth, with al intelligence and skill he took up the task which ame that of the largest part of his scientific life, and a more limited list of elements than Berzelius had estigated, produced results of a degree of accuracy ch it is high praise to say would have delighted no more than Berzelius himself. He aimed at the demination with greater precision than any one before 1 had attained of the atomic weights of some ten or Ive of the elements. But by so determining these stants he endeavoured also to settle several general stions of fundamental importance in regard to matter studied by the chemist. Thus it has generally been assumed as true beyond pute since the early part of the present century, that mass of an atom of a given element is a constant ntity. This has, however, occasionally been doubted, 1 Stas himself considered the question as one requiring mination. His researches, however, lend no support it. On this point Prof. Mallet expresses himself ongly in favour of the orthodox view. Assuming that the atomic weights are immutable values, e question arises, Are they commensurable? This is : much-discussed hypothesis of Prout, the origin and velopment of which is very fully discussed by Prof. illet. A widespread feeling at one time undoubtedly sted among chemists that Prout's hypothesis, that the mic weights of the other elements are integer mules of that of hydrogen, if not true in its original form uld ultimately prove to be so at least in a modified n. That Stas began his work under the influence of › feeling is clear from his own words :— Je le dis hautement lorsque j'ai entrepris mes rerches, j'avais une confiance presque absolue dans actitude du principe de Prout." But his experimental results clearly contradicted the othesis, and he satisfied himself that the atomic ghts of the elements which he determined with such cision could not with truth be represented by integer Itiples of the atomic weight of hydrogen, or the half he fourth of this unit. In his own words : Aussi longtemps que, pour l'établissement des lois régissent la matière on veut s'en tenir l'expérience, doit considérer la loi de Prout comme une pure sion. La simplicité de rapport de poids que prépose l'hypothèse de Prout entre les masses qui erviennent dans l'action chimique, ne s'observe donc nt dans l'expérience; elle n'existe point dans la lité des choses." The great majority of chemists-Prof. Mallet remarksat the present day, are probably agreed in believing that the hypothesis of Prout has been shown by Stas to be untenable. But the fact that so many well determined atomic weights, referred to hydrogen as unity present numbers nearly approaching integers, is very striking and calls for further investigation. Stas himself is quoted as admitting this much. Prof. Dewar, in the course of the discussion after the paper was read, drew special attention to this question and gave several most striking instances of the nearer approach to whole numbers which resulted from a recalculation of the accepted values, using the lower value for oxygen (15.87) which so many recent researches tend to support, although on the other hand, of course, some of the values now near to whole numbers are considerably thrown out. Evidently there is ample opportunity for further experimental investigation of this all-important problem, and it is impossible- notwithstanding the extraordinary degree of accuracy attained by Stas-to formulate any final conclusion. The supreme interest attaching to the problem was clearly recognised by Stas himself, as the following words show:"Au point de vue de la philosophie naturelle, la portée de l'idée de Prout est immense. Les éléments des corps composés que nous considérons comme des corps simples en égard à leur immutabilité absolue pour nous, ne seraient eux-mêmes que des corps composés. Ces éléments, dont la découverte fait la gloire de Lavoisier et a immortalisé son nom peuvent être considérés ainsi comme dérivant de la condensation d'une matière unique nous sommes naturellement conduits à l'unité de la matière, quoi qu'en realité nous constations sa pluralité, sa multiplicité." This quotation is almost alone sufficient to show that Stas was a philosophical chemist of the highest order, and not a mere mechanical worker, as has sometimes been supposed; his unwearied attention to minutest details has undoubtedly served to completely overshadow the philosophical motives and aspirations by which he was guided. Stas also endeavoured to obtain evidence with regard to the possible dissociation of the elements at high temperatures and to this end purified his materials with every imaginable precaution. The skill with which he carried out his operations is attested by the statement made by Mr. Crookes,the chairman at the reading of Prof. Mallet's paper, that he had seen in Stas's laboratory a large mass of potassium chloride, which Stas had been years in preparing, and in which he had failed to find a trace of sodium even spectroscopically-such an achievement appears almost inconceivable to the chemist. Stas, in fact, in the course of his work investigated the methods of analysis to be used with a degree of rigour, and discovered and applied refinements upon older methods of experiment with a degree of patience and skill, such as had never before been used in chemical investigation. Only those who are thoroughly conversant with such work can fully appreciate his labours; they probably will agree that owing to the multitude and diversity of the precautions to be taken, his work is the most difficult hitherto attempted, and that he stands unsurpassed among all who have undertaken the execution of exact physical measurements. A lengthy section of Prof. Mallet's paper is devoted to the consideration of the objects to be aimed at and the methods to be pursued in future work. He advocates the repetition by competent hands of some one at least of Stas's fundamental results, calling attention to Stas's own emphatic expression of the wish that this should be done. It is also most important that no distinction should be made between rare and common elements, and that the atomic weights of all should be determined with the least possible delay and the highest attainable degree of accuracy. Certain of the elements particularly call |