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Baker; and “Notes on Mexican Archæology,” by F. W. acid have been prepared. They are all red or brownish-red Warner.

solid substances possessing properties similar to those of titanium Messrs. WM. BLACKWOOD AND Sons will publish, in the phenylate. course of a few days, a short treatise on Farmyard Manure,” The additions to the Zoological Society's Gardens during the by Mr. C. M. Aikman, Lecturer on Agricultural Chemistry, past week include a Grivet Monkey (Cercopithecus griseoWest of Scotland Technical College.

viridis 8 ) from North-east Africa, presented by Miss G. A. MESSRS. SMITH, ELDER, AND Co. have issued a third edition Vicars; a Leopard (Felis pardus 8) from Ceylon, presented by of the “ Junior Course of Practical Zoology,” by Prof. A.

Mr. Marcus W. Millett; a Lesser Sulphur-crested cockatoo Milnes Marshall, assisted by Dr. C. Herbert Hurst. Advantage (Cacatua sulphurea) from Moluccas, presented by Mrs. Kate has been freely taken of corrections and suggestions received Taylor ; a Greater Sulphur-crested Cockatoo (Cacatua galerita) from many sources. The whole book has been carefully revised, from Australia, presented by Mr. Earle Whitcombe ; a Common and some new figures have been added.

Zebra (Equus zebra ! ) from South Africa, a Wonga-wonga

Pigeon (Leucosarcia picata) from New South Wales, a The Royal University of Ireland has issued a supplement to its Calendar for the year 1892. It includes the examination deposited; a Yak (Poëphagus grunniens 8), born in the

Cereopsis Goose (Cereopsis nova-hollandia) from Australia, papers used in 1891.

Gardens. A NEW series of compounds, in which the hydroxylic hydrogen of phenols is replaced by the element titanium, are described by

OUR ASTRONOMICAL COLUMN. M. Lévy in the April number of the Annales de Chimie et de Physique. The first member of the series, that derived from the Périgaud and Boquet have independently made some observa,

ASTRONOMY AT THE PARIS ACADEMY, APRIL 11.-MM. simplest phenol, carbolic acid, CgH,OH, possesses the composi- tions of the latitude of Paris Observatory, one of the objects of tion TiO.(C Hz), or Ti(CoH;0).. The discovery of these somewhat the investigation being to determine whether the value underremarkable compounds was the result of an investigation con- went a periodic variation. The two series of observations only cerning a colour reaction of titanic acid. M. Lévy had observed differ from one another by about one-hundredth of a second of that when a small quantity of titanic acid was brought into definite evidence of variability was obtained. Admiral Mou

arc; the value derived from them is 48° 50' 11"'on. No contact with sulphuric acid containing a little phenol, a deep chez, in commenting upon these observations and a disred coloration was produced. The red colouring matter was cussion of the latitude of the Observatory, made by M. soluble in the oil of vitriol, but was decomposed when the Guillot in 1879, said that doubtless the variation found at other solution was diluted with water or neutralized by alkalies. The

Observatories was wholly or in large part due to the influence of red substance has, however, been isolated by employing another

temperature on astronomical refraction. A photograph taken

by Dr. Gill was presented by Admiral Mouchez to the mode of preparation, and proves to be the titanium phenylate, Academy. It embraced an area of 20 x 2°, and on this skyTi(C&H:0),, above mentioned. It may readily be prepared by space from 30,000 to 40,000 stars had left their impressions, the action of titanium tetrachloride, Tici, upon a solution of besides two nebulæ. The exposure given was 3h. 12m. instead phenol in benzene. The titanium tetrachloride, in quantity one

of the ih. which is given to plates for the “Carte du Ciel.” If molecular equivalent, is poured directly into the solution of four

this exposure were possible for the whole photographic map of

the heavens, about 300,000,000 stars would record their existmolecular equivalents of phenol, when a very energetic action ence instead of 30,000,000. occurs with liberation of a large quantity of hydrochloric acid Swift's and Denning's comets have been observed at Bordeaux gas. The last traces of hydrochloric acid are removed by means on several occasions. The former is described as very brilliant, of a current of hydrogen, the reaction flask being warmed to

with a nucleus of about the seventh or eighth magnitude, a head about 70° by means of a water-bath and fitted with a reflux

about 8' in diameter, and the trace of a tail. M. Landerer has

compared the calculated time of eclipses of Jupiter's satellites condenser. Upon the completion of the reaction the benzene is given in the Connaissance des Temps with the actual times evaporated off, when the new compound is left behind in the observed. The agreement between the two is very remarkable. form of large crystals. The crude substance thus prepared is SOLAR HEAT.-Volume ii. of the Transactions of the Astro. then recrystallized from a mixture of benzene and petroleum, nomical and Physical Society of Toronto (1891) has recently when it is obtained in the form of rhombohedral crystals of the

been issued. li contains several interesting papers, one of

Two colour of bichromate of potash, and which, like the latter which, by Dr. Joseph Morrison, deals with solar heat.

theories have been advanced to account for the source and compound, yield a powder much yellower in colour upon

maintenance of the heat of the sun. One ascribes the heat to pulverization. The crystals are readily soluble in benzene,

the energy of meteoritic matter falling on the sun, the other toluene, alcohol, or ether. They also dissolve in concentrated asserts that the supply of heat is kept up by the slow contraction sulphuric acid, producing the same red oil which is formed in of the sun's bulk. "Taking the “solar constant” as twenty-five the colour reaction above described. The action of water upon calories per square metre per minute, Dr. Morrison calculates the crystals of titanium phenylate appears to be of the nature of that the linear contraction of the radius of the sun which is

requisite to keep up the present rate of radiation, is o '000004972 saponification. It occurs in at least two stages, a compound feet in 1 second, or 1569 feet in a year, or 29*716 miles in TiO,H,(CH3)2 being first produced ; this intermediate com- a thousand years. “Now 450 miles of the sun's diameter pound passes eventually into titanic acid, carbolic acid being at subtends at the earth an angle of 1", and therefore it would the same time formed in the solution. Fuming nitric acid, when require 7575 years for the sun's angular diameter to be reduced in large excess, converts titanium phenylate into titanic and by 1" of arc, which is the smallest angle that can be accurately picric acids ; but if only a small quantity of nitric acid is employed, theory of solar energy, a calculation shows that a quantity of

measured on the solar disk.” With regard to the meteoritic titanium picrate is precipitated in the form of a black insoluble matter which weighs one pound falling freely from infinity to substance. Nascent hydrogen, liberated by means of dilute the sun would develop by its kinetic energy 82,340,000 units of hydrochloric acid and zinc or tin, reduces the titanium in titanium heat. From this it can be found that the heat radiated could phenylate to titanium trichloride, with production of the usual be developed by the annual impact on the sun of a quantity of violet coloration due to that compound. Gaseous chlorine

meteoritic matter a trifle greater than 1/100th of the earth's

mass, and having a velocity of 382.6 miles per second. rapidly converts the crystals of titanium phenylate into titanium

PERIODIC VARIATIONS IN LATITUDE.—Mr. Chandler, in tetrachloride and the di-chlorine derivative of phenol. In

some recent numbers (248 and 249) of the Astronomical Journal, addition to titanium phenylate, the analogous compounds with announced the discovery that the earth's axis of rotation revolves the cresol phenols, thymol, naphthol, resorcinol, and salicylic round her axis of maximum moment of inertia in a period of about 427 days. In the Monthly Notices for March, Prof. New- arrangement in space of the atoms in molecules, which no comb contributes a paper on the “ Dynamics of the Earth's Rota- occupies so many investigators. tion," in which this result is mentioned with reference to the So it is a bloody feld, whose present condition I have under. periodic variations in latitude. By dynamic principles the ratio taken 10 represent to you to-day. Do not fear that I shall bring of such a rotation to that of the earth's revolution “should be the uproar of conflict into this hour of peacesul looking backequal to the ratio of her polar moment of inertia to the difference ward and forward. I have rather called up these recollections between the equatorial and polar moments.” This gives a time in order to awaken in you the consciousness that this strife, of rotation of 306 days. Mr. Chandler's result, as Prof. New. which has indeed not been wanting in the more recent years of comb says, "at first sight seems in complete contradiction to the development of general chemistry, is no abnormal phenothese principles," and he is led to inquire into the theory which menon, possibly called forth by an unusual inferiority of the assigns the time of rotation. The present paper is the result of newly appearing general ideas or of their defenders, but that it such an investigation, and he finds that two defects have made is only a question of the normal birth-pains which unavoidably themselves apparent--"namely, the failure to take account of accompany the appearance of important generalizations. the elasticity of the earth itself, and of the mobility of the ocean." But before taking up connectedly these newer and newest If the earth be considered first of all to be rotating as a homo-things, it will be in place to cast a glance over the development geneous spheroid covered by an ocean of the same density as of those fields whose progress has been of a steady nature. itself, the axes of rotation and figure would of course he perfectly First, as concerns the atomic weights. The investigations coincident. By supposing a slight displacement of the axis of which have been carried on for some years by American and rotation of ":20 in the case of our earth, he estimates approxi- English investigators—Cooke and Richards, Morley, Lord mately one-fourteenth of this as the movement of the axis of Rayleigh, Noyes, Ditimar, and others-upon the relation befigure in consequence of the shifting of the ocean. As two- tween hydrogen and oxygen, have not yet been brought to a sevenths are required by Mr. Chandler's results, "the ocean dis- close. While most of the determinations have united to indiplacement only accounts for one-fourth of the difference.” Since cate that the ratio of the atomic weights of these elements is

he remainder must be attributed to the elasticity of the earth, I to 15-87, thus differing about 0.8 per cent. from the previously he inquires into the rigidity that our planet must have, so that assumed value i to 16.00, yet by means of a well-thought-out the displacement of the axis of figure may be two-sevenths that method, Kaiser has found first 15'945, while he has now just of the axis of rotation : the result of the inquiry is to find that announced that the most probable value is the old I to 16.00.' It a rigidity greater than that of steel must be assigned to it. The is remarkable that the efforts of so many investigators to determine effect of viscosity, he mentions, makes the normal pole move slowly this fundamental constant accurately to within one part per and continuously towards the revolving one, so that in time thousand have not yet met with a generally accepted success. they would meet if they were not acted upon occasionally by some In this connection are to be mentioned ihe discussions, which opposing forces. The pole of rotation, according to Chandler's have been held upon the question as to the practical unit for the period, makes six revolutions in seven years, and Prof. New atomic weights, whether 0 = 16'00 or 15'96 should be employed. comb investigates the effect of an “annually repeated cause." This is not the place to test the grounds adduced on both sides. that might produce such a change in the position of the earth's Perhaps it may be possible, with the present stricter organizaaxis. This effect, as he points out, would be cumulative for one- tion of our Society, to form a commission which shall subject half the period of seven years, and as the displacement is small, the question to a general examination, and which, by the standa comparatively minute disturbing force can be looked for. Basing ing of its members, shall be endowed with sufficient authority to his calculations on Chandler's period, he finds that such an effect insure to its decision some prospect of general acceptance. can be obtained, for, "if the winters in Siberia and in North The question as to the connection and significance of the America occurred at opposite seasons, we should have no diffi- numerical values of the atomic weights has made no progress culty in accepting the sufficiency of annual salls of snow to of importance since the fundamental researches of Lothar account for this anomaly."

Meyer and Mendeleeff. Indeed, speculations do not cease in the direction given by the assumption of a compound nature of

the elements, yet I know of none for which I could dare RECENT ADVANCES IN PHYSICAL

prophesy growih and development. Steady work in the

revision of the numerical values of the atomic weights has CHEMISTRY.

been patiently prosecute. I need mention especially only the IN its course of development from a descriptive into a rational close of the researches of the untiring Seubert upon the metals

science, chemistry has, in a tolerably regular series of of the platinum group; and we should recognize with great changes, passed in turn through periods of more special and thankfulness the devotion with which this work, so thankless in of more general interest. While the gathering together of itself, has been carried through. empirical facts proceeds in quiet, steady work, little troubled

No new elements of importance have come recently to light. by minor and rapidly decided differences of opinion, it is regu

Although in the garden of the “rare earths" many a blossom larly noticed, upon the other hand, that more generalizing ideas,

has appeared, there fail as yet any real fruits. brought forward for the purpose of a rational comprehension

In the theory of gases the investigations continue according and unifying of this material, obtain only in the rarest cases a

to the general equation of condition (Zustandsgleichung), in that kindly, immediate reception. On the contrary, the reaction the recognition is steadily breaking its way, that the nearest which such things at first call forth is almost always a more or

entrance to the theory of liquids leads necessarily over the less violent opposition, its precipitate is to be sought out upon

critical point. The kinetic hypothesis, which was greeted in its the filter of the scientific literature of the time, there coming time with so much sympathy, and has enjoyed such careful afterwards to our view, in the text-books, only the clear filtrate attention, is showing itself here essentially unfruitsul, since the of the pure results. This has scarcely ever appeared more

two main principles of the theory of van der Waals, to which strikingly than in the fall of the phlogiston theory: the perio- the immediate future undoubtedly belongs, are independent of dicals and books of the last century resound again with the the kinetic hypothesis. In fact, neither the assumption that strife of the opponents, and often enough were the moral qualities only the space which is not filled with the substance of matter of the newer party attacked when the opposed arguments became follows Boyle's law, nor the assumption that this matter posthreadbare ; whereupon from the attacked party a corresponda definite representations whatever in the sense of the kinetic

sesses still some energy of reciprocal action, necessitates any ing reply was never lacking. The intellectual combat died away but slowly, until the new territory was occupied in common

hypothesis. in peace and harmony. We have lived through a similar

Among the experimental researches upon these relations are experience in the change from the electro-chemical theory 10

especially to be mentioned those of Ramsay and Young. The the substitution-theory, in the transfer from the idea of equi- relation determined by them, that within a very wide range the valents to that of molecular quantities, in the transformation of equation plv - )) = fT is true, or that the co-volume, 6, is the radical theory into the theory of types and structure.

Even independent of the pressure, is one of the few general facts the younger men among us remember the strong opposition which are leading us to a more accurate knowledge of the general with which was greeted at its first appearance that idea of the equation of condition.

In solving the task of finding a theory of the liquid condition, 1 Address delivered before the united Sections of Fhysics and Chemistry at the yearly meeting of German Men of Science and Physicians at Halle, to be here subject to the more simple laws. As yet but sew such have become known, and still fewer have been considered in relation between the coefficient of refraction and the dielectric this manner. In addition to the above-mentioned result of Ramsay constant, from his wide-reaching speculative investigations, and Young, there claims attention one discovered by the Hun- which latter had yielded a complete analogy of the mathematical garian physicist Eötvös, according to which the molecular surface expressions for electrodynamical and optical action at a distance, energy, as expressed by the product of the capillary constant together with an approximate equality of the fundamental conand the įrd power of the molecular volume, is shown to be stants, and which have been finally made fruitful by the brilliant a linear function of the temperature. Since the surface energy experimental investigations of Hertz. This dielectric constant stands in closest connection with the energy of interaction, by is in turn, according to an expression due to Clausius, a simple virtue of which the substance of liquids, in contrast to that of function of that fraction of the total volume of a dielectric which gases, assumes its own proper volume, and to which is accord- is occupied by the actual material substance (considered as con. ingly due the characteristic existence of the liquid condition, it ducting). But this so called true molecular volume is, finally, becomes at once evident that here certainly a means of access to nothing but the co.volume in the equation of Van der Waals. the theory of the latter is afforded. This means may be ex- There is accordingly to be expected a close connection between pected to lead more rapidly to the goal than the methods the critical constants and the molecular refraction, and Guye has hitherto almost exclusively tried, based upon a relation between shown that the expected connection actually exists. volume, temperature, and pressure.

we shall bave to seek other properties, which show themselves September 24, 1891, by Prof. W. Ostwald, Ph.D., of Leipzig.

Although spectrum analysis, with its manifold applications, has The stöchiometry of the liquid organic compounds, founded for years had almost no rational development, it has recently taken by Hermann Kopp, has enjoyed likewise a steady development. a quite promising start in the stochiometric direction. The theoWhile the question of the boiling-point seems to be essentially retical and experimental researches of Balmer, Deslandres, Julius, postponed until the general theory of liquids becomes known, Rydberg, Kayser and Runge, and others, indicate already that yet that of the molecular volumes has reached a stage which the time is not sar distant when there shall be simple and intelligible already assures the prospect of a successful period of develop regularities in this field, which until now has been so overgrown ment. The additive scheme, proposed by Kopp as a first with unfruitful hypotheses. Only upon one point I wish at this approximation, according to which the molecular volume is the opportunity, as a chemist, to direct the attention of the physicists. sum of the atomic volumes-a scheme whose insufficiency Kopp It is held as an undoubted dogma that at the highest temperahimself had shown in the case of oxygen-determines only the lures, as, for example, in the electric light arc, all compounds roughest outlines of the phenomenon in question. Other factors must be dissociated into their elements. This view is certainly make themselves everywhere felt ; as was shown by Kopp not justified. What we do know about the stability of com. for oxygen—that the portion of the molecular volume due to pounds is, on the contrary, that all compounds which are formed it can assume different values according to the function of this with absorption of heat become more stable with rising tempera. element in the compound, i.e. according to the constitution ture, and the reverse. Because the majority of the compounds of the molecule-so the same holds for the other elements. An known to us are formed from the elements with evolution of essential difference between univalent and bivalent elements is, in heat, and correspondingly become more unstable with rising this respect, not present : ethylene and ethylidene chlorides temperature, the conclusion has been drawn that this is in have different molecular volumes, although they both contain general the case. But if we reflect that cyanogen and acetylene, saturated carbon atoms, and, in addition, only univalent iwo compounds formed with great absorption of energy, are elements.

readily formed in quantity, at the highest temperatures, in the We must, accordingly, more than ever before, recognize the blast furnace and in the Davy arc light, we become conscious molecular volume as a constitutive properly. This recognition that the spectra occu

ccurring at high temperatures may, under removes at once the firm barrier to which the additive scheme, proper conditions, belong to compounds which, formedu with greatly against the will of its originator, had hardened. In vain great absorption of energy, may have a fleeting existence con. had been for so long striven to "force the facts into this form ; fined to those temperatures only. From this point of view, ever and again their living body would not fit upon the wooden many difficult facts of spectroscopy and spectrometry would have cross. Now we see that this undertaking was necessarily in some prospect of a proper interpretation. vain : we begin to comprehend that methyl alcohol must be At the extreme houndary of the optical properties, towards more different from ethyl alcohol than ethyl alcohol from propyl the side of the constitutive character, stand finally colour and alcohol; and that these two, again, must stand in a different rotation of the plane of polarized light. Although the first relation than do propyl alcohol and butyl alcohol, although each property is decisive for one of the most important branches of time the “same” difference of CH, is at hand—that there are, iechnicai chemistry, the dye-stuff industry, still but little is in short, no two pairs of compounds whose differences are entirely known as yet about the connection of colour with composition the same.

and constitution. The investigations of Krüss, Liebermann, Now, it is quite 'dependent upon the nature of the property and more recently Vogel, all indicate that the property is in considered, in what relation the additive foundation stands with great measure constitutive, becoming additive only within the the modifying effect of constitution. With the molecular volume narrowest limits of closely-related compounds. This renders the first is comparatively superior ; with the boiling points, how correspondingly difficult a recognition of the connections at ever, the latter make themselves to the most superficial observation hand.' Some time later, on the contrary, directly on account of so energetically felt that, since the attempts of Schröder, Löwig, this marked constitutive character, the colour will be an imand others, which over fifty years ago failed to carry through the portant aid in the determination of constitution ; at the same additive scheme for the boiling points of organic compounds, time, when we shall have learned to recognize this connection this line of effort has been definitely given up. The other pro- with some certainty, the discovery of new dyes with definite perties which have been studied fall between these two limits. properties will be no longer a matter of a lucky hand and of an

This holds especially for the molecular refraction. Just as unconscious feeling for this connection, but will rext upon just Buff had earlier shown that “double bound” carbon possesses as broad a basis as, for example, the technic of the metallurgical a greater molecular volume than does saturated carbon, it processes. has been demonstrated by Brühl that a similar relation holds The constitutive character of the rotation of the plane of polari: for the molecular refraction. This influence of constitution is, zation has been always known and recognized. Since van'ı Hoff however, not the only one; a similar inference has been shown and Le Bel, twelve years ago, pointed out the connection for oxygen and likewise for chlorine, and it has been repeatedly between this property and the presence of an "asymmetrical " shown that, even if approximately additive laws be followed carbon atom, i.e. one joined with four different elements or among the higher members of homologous series, yet these do groups, this idea has, at first slowly, then more and more not apply for the first members. This is necessarily so, as has rapidly, had an important development. For the "optical already been shown in discussing molecular volumes.

symmetry" shown by Pasteur in ihe tartaric acids, the el. The magnetic rotation is a property of much more strongly amples have become more and more numerous ; the researches marked constitutive character ihan are molecular volume and of 'Wallach on the ethereal oils have especially furnished molecular refraction. We possess here most excellent inves- valuable material. The presence of optical activity is now held tigations by Perkin, which have often been found of service in as an entirely ondoubted proof for the presence of asymmetrical determining questions of constitution.

carbon, and Le Bel has just announced that he has succeeded In relation to the connection between the different properties in the preparation of optically active nitsogen compounds conof substances a freitful line of thought has been carried out by taining an asymmetrical nitrogen atom, Philippe-Gaye. As is known, Maxwell had derived a definite The investigator whom we have already mentioned, Philippt.

Guye, has made a remarkable attempt to find laws for the of a laboratory as formerly the Hofmann apparatus for deternun.erical values of the molecular rotation, by giving to the mining vapour densities. asymmetry of the carbon atom a numerical measure de- It has naturally come to pass that, together with the suddenly pendent upon the masses joined thereto, and, in cases of increased range of molecular weight determinations, our views analogous compounds, comparing this with the values for the of the nature of this quantity and of the therewith connected molecular compounds. While this attempt has been well question of valence have undergone a corresponding change. supported by a number of older measurements, especially those The conception had become gradually rather dogmatically rigid: of Pictet on the esters of the tartaric acids, yet his own deter. it was understood to require for each substance only a single minations on the active amyl derivatives have not indeed fur- absolute molecular weight, the variations observed, for nished much very favourable evidence. He has not overcome example, in the case of acetic acid, being characterized as the difficulties of obtaining pure material, and certain facts were anomalies. Molecular weight determinations in solutions have observed contradicting the assumption that the sense of the shown that such variations are so extended, and, at the same asymmetry is due to the masses added. It is not improbable time, occur so regularly, that they may no longer be pushed aside that this difficulty will be overcome by placing the optical as anomalies. It is therefore at present generally recognized moment, if I may be allowed the expression, not proportional that a substance may quite well have different molecular weights, simply to the mass of the atom ; there is rather to be suspected standing in the ratio of simple multiples, the most importao! a connection with the atomic refraction.

weight for the chemist being of course the smallest of them. We turn now to a field whose development belongs entirely The consequences connected with van 't Hoff's discovery to the last few years, to that of solutions. If we call to mind being so important and wide-reaching, they have had in general the old saying, Corpora non agunt nisi fluida, vel soluta, we a friendly receptior, although a few scientific men- not of the perceive at once the very great importance of the field; all highest rank-fearing the little plants cultivated by them to be enrational knowledge of chemical processes must be preceded by dangered by the food of light falling upon them, have attempted a corresponding knowledge of the condition of dissolved a slight resistance. On the contrary, all the uneasiness which is substances.

unavoidably connected with important revolutions has been I do not need 10 remind you that van 't Hoff's discovery of directed against a second idea, which, appearing somewhat later the identity of the laws of gases with those of dissolved sub- than that of van 't Hoff, removed a fundamental difficulty in stances, is to be characterized as the greatest step forward which the theory of solutions, which had until that time made its has been made in this direction. If we reflect that the de- acceptance impossible for me. This idea has at the same time velopment of the molecular idea, which rules the chemistry of shown itself as an aid to investigation to be of unexampled to-day, is most decidedly based upon the laws of gases in their sweep and value. This is the theory of electrolytic dissociation, simple form, we recognize at once that all the important rela- of Arrhenius. tions which have been here found can be directly transferred to It is certainly to be presumed that the fundamental idea of the domain of solutions. The latter has, however, at the same this theory is generally known. In the aqueous solutions of the time, far more varied possibilities in the form of its phenomena. electrolytes, the salts, acids, and bases, a greater or less proporWhile in the case of gases only two of the variables, pressure, tion of the dissolved molecules are regarded as split up into volume, and temperature, are independent, there is present for electrically charged constituents or ions, which exist in the solusolutions the manifold infinity of the non-miscible and partially tion indepently of one another in the same manner as the partial miscible solvents. To this is due the appearance of a great molecules of a dissociated gas. If the van 't Hoff theory be number of new formal and numerical relations for solutions, admitted, it must be admiited that in a solution of sodium even under assumption of the simplest form of the governing chloride, for example, almost double as many individual parlaws, whereby a rich field of inexhaustible fruitfulness is made ticles or molecules are present as in a corresponding solution of accessible to investigation. In fact, after this advance by van 't sugar or urea of the same formula weight. The experimental Hoff, the theoretical investigations of Planck, Riecke, Lorenz, connection of these variations with the fact and numerical van der Waals, and Boltzmann, as well as the progressive com- amount of the electrical conductivity, first discovered by bination of theory and experiment by Nernst, have shown how Arrhenius, and which cannot be denied, furnishes the basis varied and valuable are the results to be gained, results whose for the second part of the theory of Arrhenius, the assumption details I am here compelled to omit.

of electric charges upon the separated molecular constituents or I wish, at this opportunity, to call attention to one particular ions. If now these fundamental ideas are accredited, the repoint. I have already mentioned that the way to a rational mainder follows with directly evident necessity. theory of the liquid condition leads from the gases, through The significance of these views becomes apparent upon contheir variation from the simple gas laws, and through the sidering the quite astonishing range of phenomena in the most critical point, whose constants express in especially simple form widely separated parts of physics and chemistry, which have the individual properties of the kind of matter in question. received explanation from the theory of Arrhenius in connection Now it is to be expected from the theory of solutions, and it with that of van 't Hoff. It is simply impossible in the limits has been demonstrated in detail by 0. Masson and W. Ramsay, of this address to even enumerate these single applications; I that upon transition from a dilute to a concentrated solution we shall, as I think, do better by treating the question from a more observe entirely the same phenomena that appear when the general standpoint, and, without speaking in particular of each volume of a gas is diminished; there is here also a critical advance made, sketch in rough outline that field in wbich stale with its corresponding constants. We thus have here a both theories have brought or will bring decisive explanation. second way to a theory of the condition of pure liquids, which, Let it be first called to mind that the laws of dissociation by reason of the greater variety of the phenomena, is a far more were already earlier derived thermodynamically for gases. If, difficult one ihan is that first named, but which, however, may then, in the field covered by Arrhenius, the question be one of in many cases be of assistance where the other fails.

dissociation, and the laws of gases do, according to van 't Hoff, While the already discussed parts of the newly opened terri- hold for dissolved substances, it follows that the entire theory of tory are mainly those problems with which physicists have the chemical affinity of electrolytes must be yielded by the applicaconcerned themselves, still its study has not been less fruitful tion of those laws of dissociation. This means nothing less than for chemistry in particular, especially for organic chemistry. that the problem of chemical affinity is in reality solved. To the above-mentioned variety of the relations here present The conception of chemical affinity is to be understood to corresponds an equal variety of the methods of determination of reach so far as to include all phenomena caused by the so-called that most important constant, the so-called molecular weight of inner energy of bodies. It includes, then, not only the prodissolved substances. Since the tireless Raoult bad shown years cesses especially termed chemical, but also those of vaporization ago, in a purely empirical manner, the application of the proper. and soluiion without exception as well. If it be wished in the ties of solutions to this purpose, it was reserved for the theory of latter case to preserve the ever emphasized but still unclear disvan 't Hoff to discover the rational basis of these relations, and tinction between “chemical" and "physical" processes, to the thus for the first time to give to wider circles of investigators a former may be reckoned those processes in which electrolytic feeling of security in the making of such molecular weight dissociation comes into question, and to the latter those in which determinations. Especial service has been rendered by E. this is not the case. Thus, the dissolving of oxygen in water is Beckmann in the technical development of these methods; and in this sense a "physical," that of hydrochloric acid in water a the Beckmann freezing apparatus and boiling apparatus form at chemical," process. But this distinction is secondary: it is present just as necessary and much used a part of the equipment expressed only in the greater complication of the corresponding

formulæ ; the fundamental equations remain everywhere the phenomena in which the special character of matter comes into same. In other words, the question is one of the theory of all question require for their study an extended knowledge of just conditions whereby heterogeneous substances or heterogeneous this character, i.e. chemical knowledge. And I cannot avoid phases of the same substance have assumed, after reciprocal complaining that in this direction too little is done. In the influence, a condition of equilibrium independent of the time. more recent physical literature, I have met not seldom chemical

The general theory of these conditions has been developed by views, which were, in short, fearful, and which gave to the J. Willard Gibbs sixteen years ago ; a German edition of this interpretation of the observed phenomena an entirely false magnificent and incredibly many-sided investigation is at present direction. The physicist is only 100 inclined to consider in the press. Through van 't Hoff and Arrhenius we are placed chemistry as an interior science, of which he knows a great suffiin a position to insert in the equations of this man of science, which ciency if, in the early part of his student life, he has once heard contain necessarily a great number of yet unknown functions, the its lectures. Nothing can be more wrong than such a view. By expressions for these functions, together with the numerical reason of its richer and more special store of facts, chemistry constants, and to thus solve the problem numerically from case really remains behind physics in its development into a rational to case.

science, and it will ever so remain, in the same way as physics It must, however, be borne in mind that the functions in remains behind astronomy or mathematics. But directly for this question, expressing as the sum of its single forms the total reason the beginning of the student years is the only time in energy of the system considered, are yet known only for the which to become acquainted with the varied details of chemical cases of gases and dilute solutions, i.e. for the cases where the phenomena, and to take up the enormous range of experience here inner energy has become independent of the volume. As far as offered. For, according to experience, the physicist never learns the knowledge of the equation of condition reaches, extends them later. The history of our science poinis out a number of the possibility of mastering the heterogeneous conditions and men, who, from chemists, have become physicists of high rank

; chemical equilibria. And we see at this place how the different I need name only Regnault, Faraday, Davy, Magnus, Hittorf. parts of general chemistry reach to one another the hand; the But I cannot name a single man of science who, after having been Solution of the problems which were mentioned in the first part trained as a physicist, has made one purely chemical discovery of this address is also, for that just discussed, the unavoidable of importance, for it never occurs that a physicist later learns condition of progress.

chemistry. The great range of empirical experience can only But with the range just measured off, great as it is, the limits be incorporated into the memory at a time when the latter is of the province of the van 't Hoff-Arrhenius theory are not | fresh, and it is usually already too late but a few semesters after yet reached. The dissociation discovered by Arrhenius is the student life has been begun. an electrolytic one. Accordingly, the immense number of I can, therefore, not urge my physical colleagues enough : phenomena, in which the electrically charged ions participate, send your students at first for a few semesters into the chemical belong likewise with those which here receive a new light. laboratory. We chemists must indeed do our part, in suitably The question as to the source and maintenance of the electrical rearranging the laboratory instruction ; the practice in qualitaenergy in the galvanic elements, as to the conduction of current tive analysis should, in particular, be greatly cut down, and in in electrolytes, as to the meaning of galvanic polarization, are its place preparative work in its widest sense, together with the only single points in this field. Electro-chemistry in the widest o typical forms of quantitative analysis, should be taken up. But sense, and, indeed, as much so that part which is concerned since the same requirements are to be made upon the education with essentially electrical questions as that which studies chemical of the future teacher of the natural sciences and mathematics in questions, has already received most valuable furtherance from the Gymnasia and Realschulen, it will not be difficult to soon our theory, and has yet more in prospect.

find the methods best adapted for the chemical education of all It is natural, as against this exposition, to propose the question non-chemists, without injuring the immediate purpose of the how the theory of van 't Hoff and Arrhenius has responded to chemical laboratories—the training of chemical specialists. the requirements which have been made upon it in a so extraordinarily wide-reaching and varied manner. Since I belong to i the few who make use of this aid in their investigations, I must THE GENERAL CIRCULATION OF THE freely confess that my judgment in this matter may be looked

ATMOSPHERE.1 upon as subjective ; but since, on the other hand, I hold to both theories unfortunately, not the position of a father, but only that IF the question of the general circulation of the atmosphere of an uncle of rather distant relationship, you may trust me that were referred to a meeting of educated people, one might at the time of first meeting them I was rather inclined to repel | be sure that ninety out of a hundred who could give any answer than to greet them. I can then only personally declare that at all would explain it by the time-honoured equatorial and polar no scientific idea produced in my time has assisted me in such current ; if anyone initiated in the subject sat near, one would measure as bas this one, and that I have further gained the im. observe a pitying smile upon his lips, and, if asked for his pression that the great scientific fields named have received opinion, he would relegate that current, of sacred memory, to likewise unusual furtherance from this idea. In particular the the region of the fables, or at most only allow it to hold sway, extraordinarily manifold and severe test which lies in the with certain limitations, in the tropical and sub-tropical zones, numberless numerical eonsequences of the theory in all possible ! the region of the trade-winds ; the temperate and cold zones fields, has yielded such a number of confirmations that the however would be reserved for the dominion of the variable relatively rare cases where the unprejudiced decision was winds, and of newly arisen cyclones and anticyclones, of which "insufficient” entirely vanish. Naturally must not be con

we cannot tell whence they come and whither they go, i.e. for sidered the judgment of those who, with insufficient qualifica. the origin and disappearance of which we cannot lay down any tions, set themselves up as judges, who do not attempt to test

laws, And if there were several of these initiated persons present, the theory, but only to refute it. The misunderstanding and

a discussion would at once occur, from which no one could obtain false conceptions from which such“refutations proceeded

a clear idea, and which would leave everyone with the impression have been in fact of such kind that thereout no real progress, that nothing certain was known about the subject. I suppose which is the end of every scientific undertaking, has resulted. that you have been present at such a discussion, and have appealed

I hasten to close. The concise review of the working ground to me to explain to you the present state of our knowledge of of general chemistry, which I have just attempted to give, shows

this subject. to what great extent chemistry has made use of physical means

I undertake this task the more willingly, since the question to solve her problems. It is, therefore, not especially necessary to

of the general circulation of the atmosphere has but recently urge my chemical associates that they should follow up the study entered upon a new stage, which marks a great step towards the of physics and acquire the necessary mathematical knowledge. complete solution of the question, and becanse it is very desirIt is cared for at many Universities by the more far-seeing able to obtain as wide a diffusion as possible for this theory teachers of chemistry, that this indispensable knowledge is which corresponds to the present state of the science. made as accessible as possible to our youths, and my personal

In this question especially, as in many others, the history of experience has shown me that such opportunities are gladly and the development is exceedingly instructive, and of the greatest profitably used.

value in aiding a comprehension of the subject. I propose, But the reverse does not present so favourable an aspect. therefore, that you should follow me through the different stages The science of physics requires for its extension and develop- Translation of a lecture delivered by Dr. J. M. Pernter before the Scientific ment exhaustive chemical knowledge in wany directions. All Club in Vienna.

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