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for a more searching and exact investigation of their atomic masses, e.g. elements such as tellurium, which occupies a position in the periodic system not in harmony with its atomic mass, and cobalt, which plainly occupies the intermediate position between iron and nickel, and therefore should be intermediate in atomic mass.

In a number of cases the accepted value is based on the investigation of but a single interchange, the value for iron, for instance, being practically based on the results obtained on converting the metal into ferric oxide, and vice-versa; and the relation of hydrogen to oxygen having been established by the reduction of cupric oxide. It is desirable that in such cases other and independent methods should be resorted to, eg. that oxides of a number of metals other than copper should be reduced, with the object of detecting possible constant

errors.

It is eminently desirable that an attempt be made to directly determine the ratio of hydrogen to each of the halogens without in any way bringing in the atomic mass of oxygen. Prof. Mallet suggests various methods deserving of study. Also it is very important that the metals of the yttrium and didymium groups should be further investigated. Prof. Mallet rightly terms the yttrium group the opprobrium of inorganic chemistry.

Nearly all that has been written hitherto in regard to the periodic relationship among the elements has involved the use of roughly approximate values only; but it is time that the foundation be laid for a more minute and critical study of the periodic system of classification. Anomalies in the classification as we now find it in our books, glimpses of more detailed relations than as yet clearly appear, tantalizing suggestiveness in so much of what is already before us, call for more precise determinations of the numbers we would discuss before we allow premature discussion to drift into mere fanciful speculation. In regard to the methods which it is desirable shall be pursued in the determination of atomic masses, Prof. Mallet has much to say. He discusses the selection of processes, the purity of materials, the very numerous directions in which vigilance must be exercised in order to avoid extraneous or accidental causes of error, the quantities of material to be used, the practical precautions to be observed so as to secure accuracy of manipulation and in weighing and measuring, the mode of stating and calculating results, finally calling attention to the advantage to be derived from the application of greater working force and ampler means than can be commanded by private individuals to the determination of atomic masses; with reference to this last point, during the discussion on the paper, the opinion was freely expressed that it was undesirable that such work should be carried out in organized public or semi-public laboratories. The question is, no doubt, a difficult one to settlesuch work demands a special temperament combined with genius of a high order and an infinite capacity for taking pains, qualities which must rarely occur united in a single individual. Moreover, in order that the value of a result may be appraised, it is essential to overlook every detail involved in the determination. Given the man, however, there can be no longer a doubt that every possible assistance he may require should be afforded him. It is marvellous that men like Berzelius and Stas, working all but alone and unaided, should have achieved results of such magnitude and universal importance-the moral effect of their example is certainly not less important than are the actual results of their labour.

The last section of Prof. Mallet's paper is devoted to the discussion of the form in which it is desirable finally to state the results. He here advocates the uniform substitution of the expression "atomic mass" for "atomic weight," on the ground that precision in language conduces to precision in thought—an aphorism

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far too commonly disregarded by chemists. We now clear conceptions of atoms having constant for the same element, of determinable difference of in the case of different elements, the several masses numbers of which regulate the composition of all ba substances and the products resulting from inter among them. The atomic theory has advanced beyond the condition of a mere working hypothes which chemists long stood with more or less uncer feet; but even if this were not so, considering it, th a common metaphor, only as a scaffold, there is no reason, so long as we stand on it and work from t we should be careless about tying our scaffold-pole c nailing our planks.

Lastly, Prof. Mallet urges that all atomic masses i be expressed in terms of the mass of the hydrogen taken as unity, objecting strongly to the change to 0which several writers have recently advocated, the objectionable argument put forward in favour of change being, he thinks, that the numbers we use. expressive of ratios only-that any figures are able which correctly express combining ratios, and: there are no reasons for using one set of figures than another save mere arithmetical convenience. 2 involves a grave error, as in adopting as unity the of a single atom of any particular element, prefer that one of which the mass is the smallest, we reason to believe that we express the mass of a others in terms of this as a really existent, de and constant quantity of matter. It is, indeed, d to understand when the scientific necessity in so cases of taking hydrogen as the unit is realized. the change to Ŏ = 16 can be advocated except a simple utilitarian plea that it is to the analyst's coor

ence.

Prof. Mallet's monograph is undoubtedly a mo mirable exposition of the philosophical lessons learnt from the contemplation of Stas's labours.

EXTINCT MONSTERS1

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THE volume with this title treats of large animas is clearly and simply written, without any pre at being scientific, and is an excellent book for boy unlearned people who are curious to be informed up subject of fossil animals. It would have escaped altogether but for emphatic words of praise in the p and one or two passages in which the author, with se hand information, speaks authoritatively of predecess who restored extinct types of life with the slender mar which were available forty years ago. The attract the volume and its novelty is a series of restoras saurians and mammals drawn chiefly by Mr. Smit, for the most part are based upon the restorati skeletons made by Prof. Marsh, whose discoveries inspired Mr. Smit's pencil as much as they ha fluenced the author's pen. There is not much an beneath the skins of the "Monsters," and they h aspect as though cotton-wool had taken the p muscle, or as though the drawings were models i "Lowther Arcade." This, however, is of less impa than the answer given to the question, Are they re ably faithful to nature? It does not seem to they can claim this merit; they are only reaso faithful to Marsh. Prof. Marsh draws an animals to give one type the maximum height to which the can be hoisted; while another is given the max length to which the remains can be extended. studies would not have led me to reconstruct the extinct reptiles upon the lines which are adopte

"Extinct Monsters." A popular account of some of the large ancient animal life. By Rev. H. N. Hutchinson, B.A., FGS, trations by J. Smit and others. (London: Chap nan and Hai L

e restorations. As an example of how a restoration uld not be made, we may instance the figure of Stegous ungulatus (p. 104), in which the management of limbs is out of harmony with the evidences of the scular structure of the tail, and the supra-vertebral st. The restoration of the Scelidosaurus from the s of England is unsatisfactory. There is no better ound for giving a kangaroo-like position to that animal n there would be for drawing Teleosaurus in the same sition. The mobility of the neck as drawn is astoning.

The restorations of mammals are happier. The subts diverge less from existing types. And probably the ost successful in the volume is the spirited restoration Sivatherium giganteum from the Sivalic Hills, though e Glyptodon and Irish Deer are meritorious.

In the text the author is generally content with telling e story of the history of science; but he sometimes

British Museum (Natural History), handed on to the unlearned as representing the best available classification. On page 75, the author introduces a restored skeleton of Megalosaurus, which is attributed to Prof. Marsh. The skeleton certainly is not referable to Megalosaurus, which never has the pubic bones or the ilium constructed as in the figure. The restoration has been previously used in Nicholson and Lydekker's "Palæontology," and in Dr. Woodward's "Handbook to the Geological Department of the British Museum," but we donot remember any published authorization for the use of Prof. Marsh's name as authority for confounding Megalosaurus with the allied American type.

Another example of the same kind of interpretation occurs in dealing with Stegosaurus. It is said to have been proved that bones to which the name Omosaurushas been applied really belong to Stegosaurus, and that an unnecessary name has been disposed of. The ground

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The four-horned extinct Mammal Sivatherium giganteum. The animal on the left is Heladotherium. strays into less safe matter. Thus an account is given of the eye of the Ichthyosaurus. And it is urged that the bony plates exercised a pressure on the eyeball, so as to make the eye more convex, and improve the definition of near objects. The study of sclerotic defences does not support this interpretation; and in at least one generic division of the Ichthyosauria the sclerotic plates do not overlap at all, but join each other by their lateral sutural margins.

It is perhaps unfortunate that the author gives currency to nomenclature and classification of the terrestrial types of saurians which may not always prevail. If the genera with a bird-like type of pelvis are terrestrial representatives of birds, and the genera with a reptilian type of pelvis are terrestrial wingless representa tives of Pterodactyls, then it may not be an advantage to have the Dinosaurs treated as a homogeneous group, or the divisions adopted by Prof. Marsh, or in the

on which this determination is made, not being stated need not concern us now; but it is undesirable that a popular work, whose main merit is that it does not pretend to teach the facts of science, should appear to enunciate judgments on scientific problems. Having described the immense enlargement of the spinal cord in the sacral region of Stegosaurus, the author remarks:"So this anomalous monster had two sets of brains-one in its skull, and the other in the region of its haunches!and the latter in directing the movements of the huge hind limbs and tail did a large part of the work." Remarks of this character are sure to be misunderstood, are out of place and incorrect.

The author has read much, and shown an excellent capacity for quotation, but has not always succeeded in using the newest results. He has conscientiously endeavoured to tell the story which is contained in hisquotations, but beyond this he does not pretend, except

in the occasional use of supposed scientific principles as a means of accounting for facts of animal structure. He has dealt with a subject of great difficulty with commendable clearness, and will interest readers who would be unable to follow a more technical exposition of extinct types of life. H. G. S.

ENERGY AND VISION.

THE HE interesting researches of Prof. S. P. Langley on energy and vision have recently been published in the Memoirs of the American National Academy of Sciences. From this we gather that he was led to investigate the question by the fact that it was not generally recognized how totally different effects may be produced by the same amount of energy in different parts of the spectrum. Two series of experiments were necessary, the first to determine the amount of energy in each ray, the second to observe the corresponding visual effect. The energy was determined as heat by the use of the bolometer, the heat dispersed by a prism being very nearly proportionate to the energy.

In the second series of experiments a beam of sunlight from a siderostat passes through a small hole in a darkened room and falls on a slit with a standard width of o 1 mm. It is then received on a collimating lens of 119 centimetres aperture and 755 centimetres focal length, after which it passes through a prism of about 60° refracting angle. The spectrum thus formed is reflected and brought to a focus on a second slit of one millimetre aperture by a concave mirror, any particular colour being adjusted on the slit by a rotation of the prism. This second slit is screened from all possible stray light by a dark curtain, and is used as a source of illumination for a series of numbers from a table of logarithms, which is attached to a sliding screen. The greatest distance from the slit at which the figures could be distinctly read was then determined, and the law of inverse squares applied. For the brighter colours of the spectrum, the light entering the first slit was reduced by an adjustable photometer

wheel.

Actinometric measures were made during the progress of the photometric observations, and showed a solar radiation of 15 calories per square centimetre per minute; this naturally being an essential unit.

The energy necessary to give the bare impression of luminosity in different parts of the spectrum, expressed in terms of horse-power, was found to be roughly as follows, the minimum visibile being defined as the feeblest light which is observed to vanish and reappear when silently occulted and restored without the knowledge of

the observer :

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These values were derived from observations made by a single observer, Mr. F. W. Very, and are, of course, subject to a large percentage of error.

The general results of the investigation may be best summarized in Prof. Langley's own words :

"The time required for the distinct perception of an excessively faint light is about one-half second. A relatively very long time is, however, needed for the recovery of sensitiveness after exposure to a bright light, and the time demanded for this restoration of complete visual power appears to be greatest when the light to be perceived is of a violet colour. The amount of energy required to make us see varies enormously according to the colour of the light in question. It varies considerably between eyes which may ordinarily be called normal ones, but an average from those of four persons gives the

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It appears from this that the same amount of e may produce at least 100,000 times the visual effect a colour of the spectrum that it does in another.

If now it be inquired what the actual value of ** in ordinary measure, we are able to give this also v fair approximation, and to say that the vis-viva da waves whose length is 7500 (tenth metres) being arres by the ordinary retina, represents work done in g rise to the sensation of the deepest red light of 2. o'ool of an erg in one-half second.

NOTES.

THE Prince of Wales has consented to become Chairm the Committee for the memorial of the late Sir Richard and to preside at a meeting to further the object, which wi held in the rooms of the Royal Society, Burlington Ha Saturday, the 21st inst., at half-past eleven o'clock. Adm will be by tickets, which may be obtained from Mr. Sladen, Linnean Society, Burlington House, W. (who is as secretary to the Committee), or from Mr. H. Rix, 2: secretary of the Royal Society.

THE annual general meeting of the Royal MeteororSociety will be held at 25, Gre at George-street, West. on Wednesday, the 18th instant, at 7.15 p.m., when the Re of the Council will be read, the election of officers and ca Theodore Williams) will deliver an address on "The E for the ensuing year will take place, and the President 'It

Altitudes of Colorado and their Climates," which will be trated by a number of lantern slides. This meeting preceded by an ordinary meeting, which will begin

7 p.m.

THE general meeting of the Association for the Improvers of Geometrical Teaching is to be held at University Ca Gower Street, W.C., on Saturday, January 14, the Re Taylor in the chair. At the morning sitting (II

the report of the Council will be read, the new officers elected, and several candidates will be proposed for electio members of the Association. After the conclusion of the business Mis. Bryant will give "A Model Lear! Geometry, as a Basis for Discussion." After an adju for luncheon at I p.m. members will re-assemble (2 p hear papers by Mr. G. Heppel on "The Use of Ha in Teaching Mathematics," and Mr. F. E. Marsha "The Teaching of Elementary Arithmetic." Members* wish to have any special matter brought forward at the getr meeting, but who are unable to attend, are requested to 5 municate with one of the Honorary Secretaries. All inter in the objects of the Association are invited to attend.

Dr. Ludwig BECKER has been appointed to the astronomy at the University of Glasgow.

THE Comet Medal of the Astronomical Society Pacific Coast has been awarded to Mr. Edwin Holmes, adon, for his discovery of a new comet on November 6.

On Tuesday next (January 17) Prof. Victor Horsley, F will begin a course of ten lectures, at the Royal Institution "The Functions of the Cerebellum and the Elementary

bles of Psycho-Physiology."

The Friday evening meeting

ll begin on January 20, when Prof. Dewar, F. R. S., will give liscourse on "Liquid Atmospheric Air."

THE severe frost which set in just before Christmas was ceeded by a rapid rise of temperature in Scotland on iday, but in England the thermometer did not rise much wve the freezing point until about twenty-four hours later. the 5th and 6th instant the thermometer fell below in many parts of Great Britain, and snow was falling Scotland, which after wards spread to many parts of gland. The absolute shade minima recorded were-2° at temar, and 2° at Fort Augustus, in the north of Scotland. e distribution of pressure was unusually high over Scandiia and northern Europe (inadvertently referred to in our e last week as over these islands) having reached about 31*3 hes in Central Russia on the 4th, while areas of low prestre lay over the Gulf of Genoa and the south-west of Ireland. e latter depression gradually extended eastwards, causing strong terly gales on the Irish coasts, while the anticyclone over rop: gradually gave way, the barometer at Haparanda on onday being 1.5 inch lower than a few days previously. By nday all stations reported temperatures above the freezing point, ile in the south-west of Ireland the maxima reached 47° and the south of France even 63°. These changes were accomnied by rain in most parts of the country, which added maally to the rapidity of the thaw. Bright aurora was seen on nday night in Scotland and Ireland. On Tuesday an icyclone from the north-westward was spreading over our nds, with finer weather and lower temperatures generally, it occurring in the north of Scotland and the central parts of gland. The Weekly Weather Report of the 7th instant showed t the temperature in the eastern and midland parts of Engd was 12° to 13° below the average for the week; at several he inland stations in England the daily maxima were below through the whole period.

AN enlightened Bengali, Babu Govind Chandra Laha, has tributed fifteen thousand rupees towards the expenses of the posed snake laboratory at Calcutta. We may expect, refore, that the institution will soon be in full working order. cording to the Pioneer Mail, two main lines of research will followed in the laboratory. So-called cures for snake-bites I be tested under strictly scientific conditions, and the proties of the snake poison as such will be investigated. The oratory will be the only institution of its kind in the world, I the Committee of the Calcutta Zoological Gardens, who e taken the matter in hand, expect that it will be largely orted to by the scientific inquirers who visit India during weather. In accordance with the practice of scientific oratories in Europe, a charge will be made for the use of tables and instruments at a rate sufficient to cover working enses. Work done on behalf of the Government will also harged for according to a regular scale.

HE members and friends of the Society for the Study of riety met on Tuesday to congratulate Dr. Severin Wielobycki aving completed one hundred years of life.

ROF. BAIN contributes to the new number of Mind an esting sketch of the career of the late Prof. G. C. Robertwith whose name Mind will always be intimately assod. Prof. Bain includes in his article the admirable notice obertson written by Mr. Leslie Stephen for the Spectator. E are glad to note the publication of a fifth edition, revised ugmented, of the Official Guide to the North Gallery at Royal Gardens, Kew. It includes a short and interesting aphical notice of Miss North. A map is given to convey idea of the extent to which her collection illustrates the tion of the temperate and tropical regions of the world.

A NEW edition of the list of members of the Institution of Civil Engineers, corrected to the 2nd inst., the seventy-fifth anniversary of its establishment, shows that the aggregate number of all classes is 6341, an increase during the past year at the rate of 3 per cent.

A PSYCHOLOGICAL laboratory has been established at Yale College, where Prof. Ladd has for some years been lecturing on physiological psychology. Science gives an interesting account of the new institution, which has been placed under the The labocharge of Dr. E. W. Scripture, a pupil of Wundt. ratory consists of fifteen rooms, three of which, including an 'isolated" room, are given over entirely to research. The isolated room is a small room built inside of another room; four springs of rubber and felt are the only points in which it comes in contact with the outer walls. The space between the walls is filled with sawdust as in an ice-box. The room is thus proof against sound and light, and, according to Science, affords an opportunity of making more accurate experiments on the mental condition than any yet attempted.

STUDENTS of ethnography will be interested to hear that Dr. N. B. Emerson, of Honolulu, is preparing a full account of the Polynesian canoe. In a communication printed in the new number of the Journal of the Polynesian Society he points out that the various migrations of the ancient Polynesians and their progenitors, from whatever source derived, must have been accomplished in canoes or other craft, and that the waa, the pahi, &c., of to-day, however modified they may be under the operation of modern arts and appliances, are the lineal descendants of the sea-going craft in which the early ancestors of the He holds, Polynesians made their voyages generations ago. therefore, that a comparative study of the canoes cannot fail to shed light on the problems of Polynesian migrations and relationships.

AN interesting little paper on the destruction of wild birds' eggs, and egg-collecting, is contributed to the new number of the Annals of Scottish Natural History, by Col. W. H. M. Duthie. Collectors who require to be specially dealt with he groups in three classes-the aimless, the greedy, and the mercenary. In contrast with these is "the true collector," whom Col. Duthie defines as "a naturalist, acquainting himself with birds, their habits, flight, migration, language, and breeding haunts; his egg-collecting being only one of the means of acquiring this knowledge." The true collector should collect for himself, and should never receive an egg into his cabinet unless authenticated by an individual in whom he can implicitly trust. If all collectors were of this type, egg-dealers would cease to exist, and with them would disappear the tribe of hangers-on whom they maintain.

A GOOD study of the form of eggs has been recently made by Dr. Nicolsky of St. Petersburg. He constructs an abstract formula, by which different eggs can be compared without regard to absolute dimensions. Calling the longer axis 1000, he obtains a figure representing the ratio of the longest transverse axis to it, and another, that of the distance of the obtuse end from the "centre," or point where the longer axis cuts the plane of the equator; then forms a fraction with these two figures, and takes it as the formula of the egg. Various explanations have been offered for the different forms of eggs. Dr. Nicolsky traces all to gravity. He considers that every egg not yet coated with a solid shell departs from the spherical form and elongates, simply because of pressure on it by the walls of the ovary. In birds which keep a vertical position when at rest (such as the falcon and owl) the soft egg becomes short through the bird's weight acting against the ovarian pressure. In birds which, like the grebe, are nearly always swimming, the egg lengthens, because the body weight acts in the same direction as the ovarian compression. Lastly, eggs become

pyriform (more pointed at one end than the other) in birds which, like the guillemot, often change their position, sometimes swimming and diving, sometimes perching on rocks, &c. An examination of all the eggs in the zoological collection of the St. Petersburg University fully bore out these views. Dr. Nicolsky thinks it would be useful to test the theory by experimentation, birds being kept in a vertical or horizontal position at the laying time.

FOR twelve years (1878 to 1890) M. P. Plantamour made careful observations of the displacements shown by two spirit levels (one north-south, the other east-west), in the cellar of his house at Sécheron. The instruments were transferred to the Geneva Observatory, and the work resumed by M. Pidoux in April 1891 (after six months' interruption). M. Plantamour found that the mean air temperature had a preponderating influence in the oscillations observed, while some other factors of obscure nature were involved. The first year's data at Geneva (Arch. de Sci.) reveal an annual oscillation of the ground of the Observatory about an axis directed north-east and south-west, such that the south-east part sinks in summer and rises in winter. The east side went down till July 16, then rose gradually till the end of December (29), thereafter sinking again. The extremes were · 4′′ 73 and +4′′ '85 (an amplitude of 9" 58). The variations of the south side were similar, but the amplitude somewhat greater. The north-south level showed some quite abnormal variations in the autumn of 1891, to which, however, the author does not attach great importance.

AN interesting contribution to our knowledge of the adaptation of structure to function in the human body is afforded in an investigation by Signor Minervini (of the Naples Society of Naturalists) of the blood-vessels of the skin in different parts. Portions of skin were prepared so as to show the exact structure of the chief arteries in them. The results are as follows:(1) The artery-walls of the skin in men are generally thicker than those of other organs. (2) This greater thickness is due generally, and during most of life, to thickening of the middle layer; but in childhood the outer, and in advanced years the innermost, layer is most developed. (3) The artery-walls in the hollow of the hand, the finger-tips, and the sole, are, other things equal, thicker than those in the back of the hand, the forehead, the arm, &c. This greater thickness is due chiefly to a greater development of the middle layer, and in all ages of life. The arteries in the hollow of the hand in the case of occupations involving hard manual labour show a greater increase of thickness than in the case of those with little or no such work. In these cases all three layers of the artery are thickened, but the middle layer most. (4) In women all the chief arteries of the hollow of the hand and of the back of the hand are somewhat less thick than in men. The difference is not great, but occurs at all ages.

IN a paper on the Santa Isabel Nitrate Works, Toca Chile, read lately before the Scottish Institution of Engineers and Shipbuilders, and now printed in the Institution's Transactions, Mr. G. M. Hunter has something to say regarding the origin of "caliche," as nitrate of soda is called in its native state. Some contend that "caliche " is a marine deposit, others that it is an animal deposit, while others say it is a vegetable deposit. Mr. Hunter holds the first of these views. The coast of Chile has several times been disturbed and upheaved by volcanic agency, and he suggests that a large tract of sea was enclosed and heaved up to the present height of the nitrate region, and there formed an inland sea, which, after a lapse of time under a tropical sun, evaporated, leaving the salts to percolate and form the beds of nitrate. From the formation of the ground, showing depressions and ravines leading to the sea, it is evident that immense volumes of water at some remote period have passed through them. In proof of this, Mr

Hunter points out that no "caliche" is ever found in s places, the accepted opinion being that there has been a “v out," as it is called. During a later period than that of formation of the "caliche" great floods passed over the p as is shown by the deep tracks of rivers, and the smooth wast appearance of the surface. Such periodical floods are com in tropical, rainless regions, and would not call for spe remark, but from the fact that wherever these river tracks washed surface appear no "caliche" can be found. This is well known that even the workmen never attempt to search it in such places. The only surface indication for the prese of "caliche" is rising ground covered with small black stor The "caliche" in its native state is white, very compact amorphous, not unlike rock salt, but when rich in odia assumes various colours, according to the composition u quality of the iodine it contains. For example, at times. contains masses of bright yellow, red, or blue, and again wh composed of a dull black colour, in which state it requires expert to distinguish it from costra or rock.

MR. E. LOMMEL claims to have found a simple explan of the Hall effect. A simple train of reasoning shows, he that the equipotential lines perpendicular to the lines of fr a plate are also the lines of force due to the current. lit filings are strewn upon the plate they will arrange themselv along the equipotential lines if the current be strong eno On bringing the plate into a magnetic field these lines of fur change their position. Hence the lines of flow, necessar orthogonal to the lines of force, will also change in form = position.

ACCORDING to Dr. J. Böhm, the statement that Phys infestans, the fungus which causes the potatoe diseases, bir nates in the tubers, is incorrect, nothing whatever being ko. about its mode of hibernation. He further states that the i tion of the potatoes never takes place in the soil through uninjured skin, but is always brought about through in the tubers by insects or snails. In potatoe-heaps sound he can never be infected by their diseased neighbours. An ini potatoe either does not germinate at all or produces a hen plant.

IN examining milk which is suspected to contain the taber bacillus it is usual to subject a sample of the milk to the of a centrifugal machine after separating the fat. One me of working is described by Ilkewitsch (Munchener Wochenschr. 1892). The casein in 20 c.c. of milk is coag with citric acid, and, after filtering, the residue is dissolve: 2 solution of sodium phosphate. The butter-fat is separates shaking with 6 c. c. of an aqueous ether solution, and acet is then added until the liquid is on the point of coagulating is then placed in a copper tube tapering at the bottom, and tube is inserted in the centrifugal machine and turned a rate of 3600 revolutions per minute for fifteen minutes. bacilli collect at the narrow end of the tube together with sediment and dirt. The liquid is poured off, and the ser examined microscopically. Thörner (Chem. Ztg. 182 791-2) gives another method, which is as follows :—20 Di the suspected milk are mixed with 1 c.c. of 50 per cent. 9 solution, and heated in a bath of boiling water until the saponified, when the solution turns yellowish brown. F treatment the casein and albumen become soluble in Twenty cubic centimetres of acetic acid are added, the shaken, heated on water-bath for three minutes, transfert strong glass tube, and turned in the centrifugal maching minutes. The liquid is poured off, and the sediment is *2 by shaking with 30 c.c. hot water, and again turned c centrifugal machine. The water is poured off, and the s placed upon cover-glasses, which are treated in the ordinarı

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