ite, the coxa, the first joint being in fact the coxa and trochanter, the short joint articulating it to the femur. en follow short sections on the metamorphoses of ects and their habits and haunts, and longer sections the collecting and preserving of perfect insects and væ, which are far more correct than the preceding es, though very slight and quite insufficient for the tiation of a beginner. The main part of the book is voted to short descriptions of the more prominent tish insects under their various orders and families,

illustrated by twelve coloured plates, which are idedly good for cheap chromographic work; this is by the most useful portion of the book, and well-marked ns will easily be recognized from the figures and criptions, even though many species are placed in ir wrong families.

wald's Klassiker der Exakten Wissenschaften. Nos. 1-37. (Leipzig: Wilhelm Engelmann, 1892.)

have already called attention to this admirable series small volumes. It consists of scientific papers which y be said to have marked definite stages in the elopment of science. The only fault we have to find h the series, as we have already stated, is that only German papers are given in the language in which y were originally written. All the others are transd. This is undoubtedly a mistake, for much may en depend on the precise words used by a great ster of research. In other respects the series is ellent, and should be of genuine service to scientific lents. The papers reproduced in the present set of imes are Lambert's "Photometrie," three volumes o); photo-chemical researches, by R. Bunsen and E. Roscoe (1855-59); an attempt to find the nite and simple conditions in accordance with ch the constituent parts of inorganic nature are nected with one another, by Jacob Berzelius 1-12); on a general principle of the matheical theory of induced electrical currents, by nz Neumann (1847); observations on the moving er of fire and the machines fitted for the development his force, by S. Carnot (1824).

to

LETTERS TO THE EDITOR.

Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake return, or to correspond with the writers of, rejected manuscripts intended or this for any other part of NATURE. No notice is taken of anonymous communications.]

"Aminol, a True Disinfectant."

ILL you grant me space, in order to avoid misunderstando make the following explanation ? —

I recently learned that certain samples marked "Aminol, e disinfectant" have been sent to various gentlemen, panied by a leaflet, in which my name, without my rity, is associated with tho-e samples. Allow me to inyour readers that those samples contain "aminol" in in the strength of one in five thousand. Now, the exents which I carried out with "aminol," as regards its ecting power of microbes, were made with a solution of ength of one in six hundred, and the disinfecting power strength was the following: spores of Anthrax bacilli ned unaffected after eight hours' exposure, only after an ire for twenty-four hours did the number of living spores se, but some escaped disinfection even after so long an

re.

Anthrax bacilli, Staphylococcus aureus, and others estroyed, but only after a prolonged exposure.

substance is advertised and circulated under the name eriodate crystals," and is associated with my name withauthority. Until quite recently I have made no experi

hit. A few years ago I made a few experiments, of a tentative character, with a solution which was • Periodate," but not with the substance advertised as

"Periodate crystals." With these latter I have recently made experiments, and 1 find that their solution in full strength has no disinfecting power on microbes, pathogenic and non-pathogenic, amongst which may be mentioned the bacillus and spores of anthrax, the bacillus of typhoid and of diphtheria, of cholera and of erysipelas, the Bacillus prodigiosus, the Staphylococcus aureus, and others. Likewise I find that injection of large quantities of the solution into guinea-pigs already infected with anthrax or diphtheria, has no power whatever in arresting or altering the normal course of these diseases to their fatal issue.

Tracery Imitation.

E. KLEIN.

I TOOK Occasion some months ago to publish the result of observations on my child H.'s progressive attempts at drawing after outline "copies" set before her.1 Examination of the series of her drawings made almost daily during the period from her nineteenth to her twenty-seventh month showed in them no apparent form or shape. They are simply vigorous pencil markings, answering as well to one copy as to another-or to none. Quite suddenly, however, in her twenty-eighth month, she seemed to catch the idea of breaking the "copy" (man) up into parts, and succeeded in making head, body, arms, legs, &c., in sufficient degree of relative proportion to show that here was, in her case, the rise of what I called in the article cited, "tracery imitation" of a visual picture.

At that time I had no explanation to offer, but simply recorded the observation. I have now, however, reached a way of explaining the rise of this apparently abrupt connection between muscle-sense and sight-an explanation suggested to me by a passage in Stricker's argument for the eye-movement theory of the visual apprehension of figure or outline.

Before a child begins to acquire "tracery imitation," his drawings have no shape, but they show uniformly certain systems of angles, curves, &c., due to the easiest and most natural movements of the arm. The eyes, however, have been in a measure already educated to recognize certain shapes or "copies.' There are, therefore, in consciousness two series of associations one of eye-movement sensations, a, a1, a3, a3, a*, &c., with a certain strength of revival, which we may call a: the other, an associated series of arm-movement sensations, n, n', n2, n3, nt, &c., representing a path of least resistance in arm movement. Let us call its strength or degree of tendency to progressive revival y.

Now, before the rise of tracery imitation "y is greater than x, for the reason that the arm is restricted to a very few movements, and these are largely automatic. Once start one of these movements, and the tendency to carry it out is very strong. The tendency of the eye-movement series, on the contrary, to regular revival is slight; very few objects, copies, &c., being so clear and isolated as to give frequent unbroken reproductions. Consequently, the arm-movement series, n, n', n2, &c., wins the day, and an abortive "drawing" is the result.

But the time comes soon when the reverse is true-when x is greater than y. The eye-movement series gets strengthened constantly by the repeated exploration of familiar figures, especially if, as in the case of my child, the eye be trained by having the same copies" set from day to day. On the other hand, the arm and hand movement series gets constantly lesser and weaker, since the increasing mobility of the muscles, in the varied new activities of this period of infancy, is acquired at the direct expense of the early "cast-iron" reactions which are largely organic. Both of these tendencies were very marked in H.-the first, in the more pronounced recognition of the "copies" set before her; the second, in the less uncouth manner of holding her pencil, moving the fingers, disposing the arm, &c. Hence, it is simply a matter of education that x should soon overweigh y, and the elements of the eye series a, a1, a3, a3, &c., should draw after them the arm series.

An association thus begins to be formed between the several members of the a series and certain correct elements of arm sensation these latter go to form, under this leading, a new n series, which gradually becomes independent as an acquisition. That each new tracery combination is thus learned separately is seen in the fact that after H. learned to trace certain "copies' (man, bird), she was yet entirely unable to trace any others.

Science, New York, January 8, 1892.

"Du Langage et de la Musique" (French ed.), chap. xxii.; see also his "Studien über die Association der Vorstellungen."

She was even unable to trace a circle, except as part of a man (the head).

In a paper presented at the London meeting of the International Congress for Experimental Psychology last August, I insisted that voluntary movements are possible in the child only after a great variety of motor "elements" have become available through great diffusion and mass in involuntary_(imitative) reactions. The above phenomenon, thus explained, serves to illustrate the broader position.

As there is no literature on this subject, the question of "tracery-imitation" has not even been put before, to my knowledge, I should be glad to have opinions upon it. It is evident that if one hold the other theory of the visual apprehension of figure, i.e. that it is given by sight apart from sensations, of eye-movement, he could still hold the explanation which I have offered above, by substituting for the series of eye-movement sensations, a, a1, a2, &c., a series of visual sensations, v, vl, v2, &c. J. MARK BALDWIN.

Difficulties of Pliocene Geology. CONSIDERING the very great importance which the later tertiary beds must occupy in all speculations about the origin of man and the present geographical distribution of plants and animals, it is unfortunate that they should have attracted so little attention among English geologists.

The fact is perhaps not unnatural when we consider how very scantily they are represented in this country; the Norwich Crag being virtually the only bed where remains of pliocene land animals have occurred. The Norwich Crag is itself a very puzzling bed, where marine remains and land remains are found mixed together, the whole having been reassorted, and I do not know of a single pliocene land surface remaining intact in Britain. The so-called forest-bed can no longer be classed as pliocene, but is clearly of pleistocene age. A real mark of the true pliocene horizon in Europe is the occurrence of the mastodon and its associated fauna.

If we are to use the mastodon as a test we shall have to travel southward as far as Auvergne, if we are to find a pliocene land surface in situ. Unfortunately Auvergne is a very dis. located and broken country, and the sequence of the later deposits is very hard to make out, and I much question whether it be possible to find sections showing the true reading of the beds in question nearer than Florence.

I am writing in the hope that I may persuade Dr. Forsyth Major, who knows the valley of the Arno so well, to communicate to NATURE some account of the results arrived at by the Italian geologists.

At present the question is one of great perplexity. Let me refer to two points. First, How comes it that in no part of the world, so far as I know, has a single fragment of an undoubted pliocene beast been found in a cave? The carnivora of pliocene times must have frequented caves just as much as the bears and hyenas of pleistocene times, yet how comes it that we can nowhere find any tertiary remains in any cavern? It will not do to appeal to denudation, for if there be deposits anywhere protected from denudation it is those in caves. Can it be that every mountain chain where limestone rocks occur is younger than pliocene times?

Again, we know that in America, both north and south, the mastodon survived to the end of the Pleistocene age, and lived alongside of the mammoth and the Columbian elephant. In Europe there is very great doubt whether the mastodon and any form of elephant were ever contemporaries. No doubt the teeth of the mastodon have been found with those of the elephant in the Crags, but the Crags have been so rearranged that it is impossible to draw any safe conclusions from them. It is at all events extraordinary that, according to the French geologists, the two beasts have never been found together in France. I believe the same conclusion has been arrived at by the Italian geologists, but upon this point there is some uncertainty, and it would be very interesting to have the opinion of so competent an authority as Dr. Forsyth Major upon the point. It is one of importance, for upon it depends largely the question of whether there was a continuity in Europe between the pliocene and pleistocene land, or whether, as I am disposed to believe, there was a break between the two involving perhaps a violent revolution. There are other interesting

I An abstract of the paper is to be found in Science, November 18, 1892, and also in the Proceedings of the Congress.

questions involved in the issue I have raised, upon which may possibly permit me to write on another occasion. while the burden of my present letter is to point ou little we really know about the pliocene land, and how: it would be to know more. HENRY H. HOWORT

The Athenæum Club, December 5.

Meteors.

A FINE meteoric shower was observed here on the nig November 23, from 7h. 30m. to 12h. 30m., when the vations were interrupted by cloud. The meteors were dently "Bielids," the radiant at 8.30 being near a point, k th. 20m.; Dec., 40° 30'. The radiant, however, wa well defined, its area being at least 4 in diameter. single observer, in a position which commanded only abou sixth of the visible hemisphere, the meteors numbered abc. a minute, which would indicate at least seventy-five an for the entire sky, exhaustively observed.

At ten o'clock two observers, standing back to back open space, counted 104 meteors in five minutes; the p of the radiant being then, R.A., 1h. 30m.; Dec, 4 -very near Upsilon Andromeda. At this time the m seemed to be rather more definite than earlier, and se nearly stationary meteors determined the place with reast precision.

An hour later a similar count by the same two observen 100 meteors in four minutes and a half, and the radia determined at R. A., th. 40m., Dec., 40°. The rate of quency continued about the same until the sky clouded. hour later, and must, I think, be estimated as high as f to 100 a minute for the whole number that might have seen by a sufficient corps of observers. This would footp 24,000 to 30,coo for the five hours.

I am not quite certain whether the apparent change t position of the radiant is, or is not, real; but a mothe similar in amount and direction is given by Denza in his vations of the meteoric shower of 1885 (see NATURE, VOL. I page 151).

Comet "f" (Holmes's) was about 10° west and 4° south mean radiant at R. A., oh. 40m., Dec., 360° 45'. It was visible to the naked eye.

Most of the meteors were very small, not exceeding tit magnitude; but a few, perhaps one in ten, were abo second, and in the course of the night four were seen rivalled or surpassed Jupiter. The brighter ones le? trains, which remained visible for three or four seconds smaller ones often came in "flights" of three or four and fully half the paths were more or less curved and way the resistance of the air.

It is worthy of notice that the heliocentric longitude. earth at the time of the shower was about 62°, instea which was the longitude of the descending node of Biet at the last appearance of the comet in 1852, and was the tude of the earth at the time of the showers of 1872 20 The fact suggests the inquiry whether perturbations st will fairly account for such a recession of the node.

It is obvious also that if the meteoric swarms encount the earth in 1872 and 1885 were really moving in the Biela's comet (which at its last appearance had a peri years), then the swarm encountered the other night, years later, must have been an entirely different oneindeed the perturbations since 1885 can account for a reta of nearly five months.

Last night was for the most part overcast, but a fifteen minutes through occasional openings in the cloud. only one or two possible Bielids. Evidently the show not continuing with any intensity. C. A. i

Princeton, N.J., U.S., November 25.

Comparative Sunshine.

AFTER explaining that by "sunshine" I intend thi would fall upon the earth if there were no atmospheric tion, one must first notice the very elementary truth amount of such sunshine at any assumed time and r proportion to the altitude of the sun at noon, and a 1 Our "Eastern standard time" is just five hours slower than time.

th of the day. Except at the time of the equinox, the gradual thening or shortening of the day, as the solstice is roached, most materially affects, especially in the higher udes, the total amount of sunshine received in twenty-four

rs.

ut are there any convenient and readily accessible tables-as e easily might be-which would at a glance show numerically comparative amounts of sunshine at certain selected times places? I would wish to see such tables, say, for every hday, for the three months from an equinox to a solstice, for it every third degree of latitude in each hemisphere. I see how, without this, either the causes or the effects of meteorocal changes in different regions at different seasons can be y estimated. I would propose to express the amount of hine during twelve hours at the equator at the equinox by, 100; the figures rising above this, or falling below it. s there would be more than 100 given for the latitude of the ›ic of Cancer at the summer solstice, with a vertical sun and than twenty-four hours' sunshine; with 100 for a latitude further north. REGINALD COURTENAY.

he Imperial Hotel, Sliema, Malta, November 14.

Quaternions.

y the kindness of the author I have just received a copy of Heaviside's paper "On the Forces, Stresses, and Fluxes of rgy in the Electromagnetic Field" (Phil. Trans., 1892, 23), in which he reopens a question debated in your columns e time ago the question of Quaternions versus other methods ector analysis for the use of physicists. t present the matter

are stands thus :-There

two

a

ly-known systems of vector analysis before the public uaternions and the Ausdehnungslehre-and quite itude of less known ones, of which Prof. Gibbs's seems >e one of the least open to objection, and of which, It would y opinion, Mr. Heaviside's is by no means so.

too long, however, to justify this opinion, but I to make an appeal to Mr. Heaviside and Prof. Gibbs rounds independent of the merits or demerits of their parar systems.

the Ausdehnungslehre I do not feel competent to speak. Quaternions, there are undoubtedly some inconveniences ysical applications, and I am quite willing to concede that ive one is the very frequent use of the letters S and V (Mr. viside uses the latter). I do not regard the sign of the ir product which vexes the soul of Mr. Heaviside as of any equence. But while thus admitting that a better system Quaternions is conceivable, I think I can show that the ion of the dissenters is little short of suicidal.

he band of physicists who use and urge the use on others of or analysis is woefully small. Let me put a question to two e justly best known of that band, Prof. Gibbs and Mr. viside. What is the first duty of the physical vector analyst physical vector analyst ? I think I may anticipate that nswer will be-to convince the world of mathematical cists that vector analysis must be unshelved and set to work. next question that arises is one of tactics. What should e plan of campaign to bring this desirable result about? I am afraid we cannot hope for unanimity even among embers of the small band, and this is to be most grievously red. But surely every sane man will agree that what most nly the analysts should not do is to present their arguments se they would convince in a dozen different mathematical ages, each of which is puzzling enough to those learned in languages. Grant this, and it follows that Quaternions ie Ausdehnungslehre should be left in sole possession of Id. The day for Prof. Gibbs's improvements is not yet. Gibbs and Mr. Heaviside have not yet convinced the rest small band—not to say each other of the merits of their thms. Let me implore them to sink the individual in the on cause, and content themselves with the faith that ity will do them justice.

rt from the question of notation there seem to be two s of opinion as to the proper conduct of the campaign. y the metaphor, Maxwell, Clifford, Gibbs, Fitzgerald, side prescribe a course of spoon-feeding the physical Hamilton and Tait recommend and provide strong I do not think that harm, but rather good, will come is double treatment, as one course will suit some patients But let the spoon-feeders provide spoon: other others.

meat of the same kind as the other physicians. Is not Maxwell,
Clifford, and Fitzgerald's food as digestible as Prof. Gibbs's and
Mr. Heaviside's?
ALEX. MCAULAY.

Ormond College, Melbourne, October 31.

Animals' Rights.

MR. SALT disputes the justice of the statement that he has given two contradictory definitions of animals' rights, inasmuch as, according to him, that which he has set forth on p. 28 is but a repetition and amplification of the one to be found on p. 9. By the definition on p. 9 animals' rights are said to consist in a "due measure " of the restricted freedom which constitutes the right of man, i.e. (as Mr. Salt notes) the freedom "to do that which he wills, provided he infringe not the equal liberty of any other man -"a restricted freedom" which guarantees to the harmless individual the security of his life and liberty. But on p. 28 the rights of animals (which were said before to consist in a "due measure of that just quoted) being here stated to be "subject to the limitations imposed by the permanent needs and interests of the community," are found to be burdened with so serious a qualification that security for the life and liberty of the harmless individual is by it completely destroyed.

A European might settle with confidence in an unknown island, on the assurance that he would be allowed a measure of the general right of the natives to the freedom to do that which they would, provided they infringed not the equal rights of any other, but were he afterwards to discover that the "measure" of this right which was considered to be the "due " of a foreigner was in reality limited "by the needs and interests of the community," and that, a community where the custom of enslaving and eating strangers had existed from time immemorial, we venture to assert that his departure from the island would be effected with as little delay as possible. We should much regret misrepresenting Mr. Salt's statements, but the assertion that the second definition of rights is but a repetition and amplification of the first is manifestly untenable, and if, by "due measure" for animals of the rights of man, Mr. Salt would have us understand that he meant-only such a measure as is consistent with the nullification of the most fundamental privileges secured by them, he must have been discussing the subject in a vein of sarcasm which we are bound to confess we had quite failed to appreciate. THE REVIEWER.

The Height and Spectrum of Auroras. THERE was a magnificent aurora on the evening of the 4th, part of which, from 10h. 461m. to 48m. or 49m., was an intense red. I noted the positions of some of the features at the exact half-hours and also at some other times, for comparison with any observations that may have been made in other places, for ascertaining the height of the phenomenon; and I hope some such observations have been made of the recent display, and will be made of further ones in the future, for Dr. Veeder, of Lyons (New York), has kindly consented to calculate the heights from the observations.

have as yet obtained a good photograph of the auroral spectrum. I am surprised that none of our persevering photographers I do not think it would be more difficult than the stellar photographs that have been taken, seeing that the exposure might go on for hours. It would be desirable to have it done with a camera that could be pointed in any direction at will, so that wherever the observer saw a bright portion of the aurora he could direct the instrument to it. T. W. BACKHOUSE. Sunderland, December 6.

The Teaching of Botany.

THERE appeared in NATURE (vol. xxxi. p. 229) a paper entitled 66 'Experiments suitable for illustrating Elementary Instruction in Chemistry," by Sir H. E. Roscoe and W. J. Russell. I have long felt the want of a similar series of experiments in physiological botany. There is not much difficulty in teaching the morphological side of the subject, but it is not easy for the ordinary high-school teacher to devise and carry out a suitable series of experiments for demonstrating the more important aspects of physiological botany. If some master in the

subject would do for botany what Sir H. E. Roscoe has done for chemistry he would confer a great boon on teachers and A. H. young students.

Egyptian Figs.

My attention has been called to a very obvious slip of the pen in my note on Egyptian Figs, in that I have written "Pliny' instead of "Theophrastus." The former, as all know, was a Latin author, but he simply copies from the latter. Having both authors before me at the time, I accidentally put one name for the others. The refs. are as follows:-Theoph. iv. 2; Dioscor. 1. I; Plin. xiii. 7. GEORGE HENSLOW.

A Palæozic Ice-Age.

I CANNOT understand how, when writing on this subject ante, p. 101), I overlooked the circumstance that the ancient boulder-beds of Australia, India, and South Africa received full notice in Prof. J. Prestwich's "Geology," vol. ii. pp. 143–146. December 9. W. T. BLANFORD.

SCHEELE.

DURING this month Sweden commemorates the one hundred and fiftieth anniversary of the birth of one who has conferred an imperishable lustre on her annals. Carl Wilhelm Scheele although a German by nationality, for he was born at Stralsund, the capital of Pomerania-spent practically the whole of his short life in Sweden, and is usually regarded as a Swede. The son of a tradesman, Joachim Christian Scheele, and the seventh child of a family of eleven, Scheele, as a boy, gave little promise of the genius and power which astonished the scientific world towards the close of the last century. It is perhaps indicative of a certain mental imperfection that he should have been wholly incapable of learning a foreign language; although he lived in Sweden during more than half his life his knowledge of Swedish was so imperfect that his memoirs, addressed to the Academies of Stockholm and Upsala, were invariably written by him in German and had to be translated by others before publication. By what influences he was led to the study of chemistry is unknown. There was nothing apparently in his home life, or in the mode or circumstances of his education to direct his inclination towards science. As a boy he began the study of pharmacy, and at his own wish was apprenticed to an apothecary at Göteborg named Bauch, with whom he remained eight years. Here he had access to the standard treatises on chemistry of that time, and he devoted all his leisure, often working far into the night, to the study of the works of Neumann, Lemery, Kunkel, and Stahl. Kunkel's Laboratorium was, indeed, his chief instructor in practical chemistry, and it was by diligently repeating, in the first instance, the experiments contained in that book that he acquired that extraordinary manipulative skill and analytical dexterity on which his success as an investigator ultimately rested.

When twenty-three years of age Scheele removed to Malmö, and some years afterwards to Stockholm, where he superintended the shop of an apothecary named Scharenberg. It was about this time that his career as a discoverer began, by the isolation of tartaric acid from cream of tartar. He ascertained many of the characteristic properties of this acid and prepared and examined a number of tartrates. These early efforts met, however, with a somewhat untoward reception. It seems that Scheele drew up an account of his observations and forwarded it to Bergman, who then filled the chair of chemistry in the University of Upsala as the successor of Wallerius. Bergman failed to appreciate the significance of the work of the young and unknown apothecary and by

some mischance the manuscript was lost. The impor of the discovery was, however, recognized by Retzius induced Scheele to write a second account of his won to submit it to the Academy of Sciences at Stockho whom it was eventually printed. In 1771 Scheele publa his memorable essay, " On Fluor Mineral and its Add which he first demonstrated the true composition of spar, showing that it "consists principally of calc earth saturated with a peculiar acid," named by "fluor-acid." Although he found that the "Auor (hydrofluoric acid) dissolved "siliceous earth," he f to recognize the change thereby produced in the acid" and was thus led to an erroneous conception real nature. He was in fact led astray by the cr stance that his experiments were for the most part in glass vessels, and hence the fluor-acid was con ated with more or less silica and hydrofluosilica The origin of the silica in the acid prepared by S was first clearly indicated independently by Wiegle Meyer. In 1773 Scheele went to Upsala as pha tical assistant to Mr. Lokk, in whose shop he ch to meet the chemist Gahn. Lokk and Gahn speculating on the cause of the different m action of distilled vinegar on nitre before and a fusion. This was explained by the young ass who pointed out the nature of the change effecte nitre by fusion; and the fact that it is converted salt (potassium nitrite) from which a peculiar acid, ent from true "spirit of nitre," can be obtained by ment with distilled vinegar. Gahn, struck with the sa of the young pharmacist, offered to introduce Bergman. The invitation was at first declined; Se had not forgotten the unfortunate incident of the tar acid memoir. Eventually he allowed himself to be vinced that Bergman's action was due more to inadver than to indifference, and the acquaintance which fol rapidly ripened into a strong friendship. In 1774 SC at the suggestion of Bergman, published his well-s memoir "On Manganese, Manganesium, or Man Vitrariarum." This essay, although marred and in obscured by the phlogistic conceptions of the period. for ever remain one of the classics of chemistry. Scheele not only established the nature of "pyros or "wad," but, in studying the action of acids up mineral, he was led to the discovery of baryta chlorine, the properties of which he minutely desc In 1775 appeared his memoir on arsenic acid whi prepared in several ways; he discovered many: more striking properties of this body and obtate number of its salts. In the course of the investigat discovered arseniureted hydrogen, and the wei pigment Scheele's Green. In the same year he put his essay on benzoic acid, the "flowers of bene the apothecary. After a stay of two years in s Scheele was appointed by the Medical College f* of the pharmacy at Köping, a small town on the shore of Lake Mälar. Instead of the prosperous 255 he had been led to expect he found nothing but fort and disorder, and the remainder of his life was in a constant struggle with privation and debt, re length, to some extent, by a grant, at Bergman's tion, from the Stockholm Academy. Of this Scheele set aside one-sixth for his personal Dece and devoted the remainder to his researches. 1: he took over the business of the pharmacy from the of the former proprietor, but it was only by unter industry that he was able to discharge the obliga thereby incurred. Not a year passed, however, Scheele publishing two or three memoirs, ever of which contained a discovery calculated to e his reputation as the greatest experimenter

time.

This untiring devotion to science at began to tell upon a frame constitutionally wtdoubtless further enfeebled by privation, and by th

of debt and difficulties. He struggled on, however, a martyr to rheumatism and suffering from a complication of internal disorders until he was struck down in the spring of 1786. Some time before his fatal illness he had formed the resolution of marrying the widow of his predecessor so soon as his circumstances should permit on bis death-bed he carried out this project, bequeathing to his wife such property as he had been able to acquire. Two days afterwards (May 21, 1786) he died at the age of forty-four.

The eleven years during which Scheele lived at Köping were fruitful in investigations of the highest importance in every department of chemistry. In that time he discovered molybdic, tungstic, and arsenic acids among the inorganic acids; and lactic, gallic, oxalic, citric, malic, mucic, and uric among the organic acids. He also discovered glycerin, determined the nature of Prussian blue, and prepared hydrocyanic acid. He demonstrated that plumbago is nothing but carbon associated with more or less iron, and that the black powder left on the solution of cast-iron in mineral acids is essentially the same substance. He determined the chemical nature of sulphuretted hydrogen, discovered arseniureted hydrogen, and invented new processes for preparing ether, powder of algaroth, calomel, and magnesia alba. He made numerous analyses of air by absorbing the oxygen with a mixture of iron filings and sulphur. He concluded that "our atmosphere contains always, though with some little difference, the same quantity of pure or fire air [oxygen] viz. which is a very remarkable fact; and to assign the cause of it seems difficult, as a quantity of pure air [oxygen] in supporting fire, daily enters into a new union; and a considerable quantity of it is likewise corrupted or changed into aerial acid (carbon dioxide) as well by plants as by respiration; another fresh proof of the great care of our Creator for all that lives."

33

Scheele's greatest work, however, is unquestionably his treatise on "Air and Fire," which appeared in 1777 with a preface by Bergman, who, according to Thomson, superintended its publication. This elaborate essay shows Scheele at his best and at his worst ; it testifies to his genius as an experimentalist and to his weakness as a theorist. No one can read this, or indeed any other of Scheele's memoirs, without being impressed by his extraordinary insight, which at times amounted almost to divination, and by the way in which he instinctively seizes on what is essential and steers his way among the rocks and shoals of contradictory or conflicting observations. No man was ever more staunchly loyal to the facts of his experiments, however strongly these might tell against an antecedent or congenial hypothesis. Had Scheele possessed that sense of quantitative accuracy which was the special characteristic of his contemporary Cavendish, his work on "Air and Fire" would inevitably have effected the overthrow of phlogistonism long before the advent of Lavoisier. His memoir is essentially an essay on oxygen, of which he was an independent discoverer, in its relations to life and combustion. It is perhaps idle to speculate on the causes which prevented his clear recognition of the full truth. It may have been that he was essentially a preparateur like Priestley, and that quantitative chemistry had few attractions for him; it is far more probable that the character of his work was determined by the circumstances of his position, by his poverty, his lack of apparatus, and his want of assistance. it is, it remains one of the most remarkable circumstances in the history of human knowledge that a man working under such adverse conditions in a small village on the shore of a Scandinavian lake should have been able to change the entire aspect of a science.

As

It was stated by Crell, the editor of the well-known Neue Entdeckungen and Annalen, in which many of Scheele's papers first appeared, that the great Swedish

chemist was invited to this country with the offer of an easier and more lucrative position than that which he had at Köping; but that his partiality for Sweden and his love of quiet and retirement delayed his acceptance of the offer until a change in the English ministry put a stop to the negotiations. Thomson, the author of the "History of Chemistry" in mentioning this circumstance, expresses his doubts as to its truth, and states that he made enquiries of Sir Joseph Banks, Cavendish, and Kirwan, but none of them had ever heard of such negotiation. Indeed the circumstance is intrinsically improbable. "I am utterly at a loss," says Thomson, "to conceive what one individual in any of the ministries of George III. was either acquainted with the science of chemistry or at all interested in its progress. . . . What minister in Great Britian ever attempted to cherish the sciences, or to reward those who cultivate them with success? . If any such project ever existed, it must have been an idea which struck some man of science that such a proposal to a man of Scheele's eminence would redound to the credit of the country. But that such a project should have been broached by a British ministry, or by any man of great political influence, is an opinion that no person would adopt who has paid any attention to the history of Great Britain since the Revolution to the present time."

ERNS

T. E. THORPE.

WERNER VON SIEMENS.

RNST WERNER SIEMENS was the eldest son of Christian Ferdinand Siemens and Eleonore Deichmann; he was born in 1816 at Lenthe in Hanover, where his father was engaged in the business of agriculture and forestry.

From his very childhood the subject of this memoir learnt the lessons of self-control and responsibility, for owing to his mother's delicate health and his father's occupations, the care of his younger brothers and sisters devolved on himself and his sister Mathilde; in these younger days he also learnt tact, and his father taught him that difficulties had to be faced and overcome, and that duties must never be avoided.

In 1823, a few months after the birth of his brother William (whose lamented death occurred here nine years ago), the family removed to Menzendorf near Lübeck, in the Grand Duchy of Mecklenburg. In the Gymnasium of Lübeck Werner was educated up to his eighteenth year, when, by the advice of his father-who with rare prescience saw in Prussia the nucleus of German Unity and Empire he went to Magdeburg to volunteer for service in the Prussian Army. For three years he studied in the Military School of Berlin, and in 1838 received his commission as a lieutenant in the artillery, and returned to Magdeburg; he was soon transferred to the Technical Division of the Artillery at Spandau, and afterwards to Berlin.

In July, 1839, his mother died, and six months afterwards his father; and then, at only twenty-three years of age, he became the veritable guardian of his younger brothers and sisters.

In 1842 he took out a patent in Prussia for electroplating and gilding, and having established a factory in Berlin for putting his invention into practice, he urged his brother William to devote his attention to the subject. This the younger brother did; and the story of his enterprise and success in this country then and ever since has been told by Dr. William Pole in his most interesting biography of him; to this volume and to the works of Dr. Werner von Siemens, the first volume of a translation of which has recently been published by Mr. Murray, we are indebted for much of the information

contained in this short notice.