radium salt. With regard to the power of radiation of this preparation it corresponds to 100 mgrms. of pure radium bromide, while it has cost only a third as much. Nevertheless it is not cheap, for 11,000 marks was paid for this small quantity. Thanks to a donation from Dr. von Böttinger of Elberfeld, the Berlin Academy will in a few months' time possess 250 mgrms. of it, and will lend it to German investigators. Every year from the useless residues of the manufacture of thorium in Germany an amount of Hahn's preparation can be obtained corresponding to more than 10 grms. of pure radium bromide. This is about as much as the total amount of radium salts yet obtained.

This discovery will compensate for the lack of radium from which Germany has hitherto suffered.

The sphere of experimental chemistry has been very greatly widened in the last ten years by the possibility of easily obtaining very high and very low temperatures. The former is effected by electric furnaces, by means of which 3000° is easily reached. The latter are obtained by cooling with liquid air. This can now be bought in Berlin at the cost of a medium wine, i.e., 175 m. per litre. This we owe to your Majesty, who has allowed Prof. von Linde of Munich to set up here one of his large machines for iquefying the air. In order to show how indispensable it has become to us I may mention that in this University Institute some litres of it are used every day for scientific purposes.

Liquid hydrogen, the temperature of which lies about 60° lower, is even more useful. It boils at -252-6°, i.e., only 20'4° above the absolute zero. Liquid hydrogen cannot be bought in Berlin, and it is usually not to be obtained here. However, I can show you a specimen which comes from the Physical Institute of the University of Leipzig, where it was prepared this morning, and then sent here with great care. We will pour a specimen from the specially constructed containing vessel into a transparent glass vessel, and I will demonstrate the low temperature by immersing in it a glass tube closed at the bottom. On taking the glass tube out it is seen to be filled with a white mass like snow, which is the frozen air; however, when it is removed from the cooling liquid it melts in a few seconds.

The rest of the liquid hydrogen which has been left in the receptacle will also be used for scientific purposes. For at the end of my lecture it will go to the University Institute of Physical Chemistry, in order to be used this evening and during the night by Prof. W. Nernst for heoretically important researches on the specific heat of the elements in the neighbourhood of the absolute

zero.

When the Kaiser Wilhelm Institute of Chemistry is in working order we hope not to have to send to Leipzig for liquid hydrogen.

Liquid hydrogen was first prepared about twelve years ago by Prof. Dewar in the laboratory of the Royal Institution in London. But he was able to perform this difficult experiment only owing to the abundant means placed at his disposal by the great benefactor of chemistry, Dr. Ludwig Mond. Moreover, Dr. Mond has not forgotten his German fatherland and German science. The University of Heidelberg, where he studied, received from him a bequest of a million marks for chemical and physical investigation, and he also contributed several years ago 200,000 marks to the Chemical Institute planned by us.

Inorganic chemistry which thirty years ago was regarded as thoroughly investigated has taken a new lease of life owing to these new agents, e.g., high temperatures, strong electric currents, &c. I propose now to point out some technically important processes, and shall begin with experiments to make use of the nitrogen of the air for the preparation of valuable nitrogen compounds.

The direct conversion of the air into nitric acid by powerful electric discharges has reached the stage of a major industry. In Norway, in the neighbourhood of a large waterfall, a huge factory has been started by German

manufacturers in conjunction with Norwegian engineers, financed by German and French capital. Artificial saltpetre is already on the market, and German colour manufacturers will obtain a considerable amount of the nitrous acid they require from the same source. A short time before the very original method of preparing calcium nitride from calcium carbide and atmospheric nitrogen, which was worked out by Prof. A. Frank and Dr. N. Caro, of Charlottenburg, came into use.

And yet another method has been described, by which atmospheric nitrogen has been made to combine directly with hydrogen to give ammonia. For by the ingenious application of the principles of physical chemistry, Prof. Haber, of Karlsruhe, has overcome the difficulties which have hitherto stood in the way of the practical use of the synthesis.

The well-known Badische Anilin und Soda-Fabrik at Ludwigshafen a.- Rh. has taken up his patents and so far perfected the method technically that probably we shall soon have synthetic ammonia on the market.

The more numerous such methods are, and the keener the competition among them, the better it is for the consumer. In the above-mentioned cases this has a special significance because the greater quantity of the nitrogen compounds is used in agriculture as artificial fertilisers. In the opinion of experts German agriculture could easily employ twice or even three times as much nitrogen compounds as at present, if the price were correspondingly lowered. Possibly farmers would thus be able to increase their crops to such an extent that Germany could be independent of foreign countries as regards agricultural products. Thus a problem of great national importance is put before chemical industry.

The last-named process, the synthesis of ammonia, has the advantage that it requires no electricity, but only heat, or, in other words, fuel, of which Germany has an abundant supply. It is, moreover, noteworthy that its profitable working depends upon the price of hydrogen, which in conjunction with the cheap atmospheric nitrogen serves as the raw material. The problem of preparing cheap hydrogen has already been solved by chemical industry in consequence of the stimulus offered by aeronautics. This confirms the experience that all commercial activity is interdependent, and that improvements in one region may have a very considerable influence upon very different branches.

A similar connection of mutual benefit exists between scientific chemistry and the preparation of metals. The preparation of gold, silver, and copper has been wonderfully simplified by the application of electrochemical methods. The study of metallic alloys and the cheap preparation of metals formerly difficult to obtain, such as chromium, tungsten, manganese, vanadium, and tantalum, has been put to good use in the steel industry and in electrotechnics.

And not to forget the latest novelty in this region-I have here a new sort of iron, the so-called electrolytic iron. It was prepared by the Langbein-Pfannhauser Works in Leipzig by a method which was discovered by Professor Franz Fischer working in the Berlin University Institute; in this process the metal is separated by a salt of iron by means of an electric current. Besides solid plates up to 5 mm. thick which can easily be rolled and drawn out into wire, you see here a shining lamina which is not polished, but was separated directly from the electrodes in this state; also a spirally wound iron tube without a seam which was separated in the same way on a lead mould.

This iron is different from all known commercial sorts because of its exceptional purity, in consequence of which it also possesses certain other physical properties. Thus it becomes magnetic much more quickly and also loses its magnetism very rapidly. Hence it can be used to make very effective electromagnets. This electromotor of the ordinary type standing before you had originally a horse power 0.5; when the old electromagnets had been

replaced by electrolytic iron its capacity rose to 1.25. This new iron will be of great importance in the construction of electromotors.

Nowadays our material comfort depends considerably upon the consumption of fossil fuels-coal and lignite. Later generations, however, will not spare us the reproach that we have been wickedly lavish with this valuable material. For if steam is produced by heating with coal in the ordinary way and then transformed into mechanical motion by steam engines, more than 85 per cent of the energy originally in the coal is lost. But this loss may be considerably diminished by a suitable chemical treatment of the coal. For if the coal is first converted into combustible gases, the so-called power gas, and then burnt in gas motors, the yield of effective power can be increased to three times that of the steam engine. Valuable ammonia and tar are obtained as by-products, and undoubtedly the methods at present used for the preparation of power gas are capable of alteration and improvement in many respects. I suppose therefore that in the centres of the coal industry special institutes-perhaps modelled on the Kaiser Wilhelm Gesellschaft - will appear, and in them this important question will be investigated with all the means at the disposal of science and in the closest connection with practice.

The fossil fuels which were originally derived from the vegetable kingdom also form a link between mineral and organic substances. The chemistry of the latter greatly surpasses mineral chemistry in the multiplicity of its methods and its results. This is not remarkable, for it includes all the complicated chemical substances which occur in the plant and animal body. The number of thoroughly investigated organic compounds may be estimated at 150,000, and each year is increased by 8000 to 9000. It may therefore be calculated that at the end of this century organic chemistry will include as many individuals as the living world—the animal and vegetable kingdoms together.

This rapid increase is the work of organic synthesis from a few elements, of which carbon is the chief; it builds up in a marvellous manner all these combinations, just as an architect from the same bricks produces different kinds of buildings.

Organic synthesis is a child of Berlin. It began here in the Niederwallstrasse eighty-two years ago with the artificial preparation of urea by Friedrich Wöhler. It has been mostly carried out in Germany. Now-a-days it does not hesitate to try to produce the most complicated constituents of the living organism. I will show you this in the three classes of substance which are of the greatest importance in the living world-fats, carbohydrates, and albuminoids. The synthesis of fats was performed by M. Berthelot in Paris two generations ago. The first artificial carbohydrates-grape-sugar, fruit-sugar, &c.-saw the light twenty years ago in Wurzburg. And the methods of the artificial building up of albuminous substances have been worked out in the Berlin University Institute during the last ten years. Hence I am in a position to show you one of these products. It is the most complicated substance which synthesis has yet produced, and has such a long name that I do not dare to pronounce it here. The quantity of the preparation is very small, and as you will see again presently the vessels of experts generally differ from those of the manufacturer in their remarkable smallness. This difference is of the same order of magnitude as the difference between the possessions of these two classes of men.

Nevertheless, the artificial albuminous substance like Hahn's preparation is not cheap. The raw materials which are necessary for its preparation cost about 1000 marks, and the labour involved must be estimated at a still higher figure. Thus it is not adapted for food. It is only a curiosity, but a substance which is a curiosity to-day may be useful to-morrow. Chemistry has already provided many examples of this.

To be continued),

125

BEARING OF THE SOLVATE THEORY OF

SOLUTION.*

By HARRY C. JONES.

(THE evidence for the solvate theory of solution has bee furnished through investigations carried out in this laboratory, largely with the aid of grants from the Carnegie Institution in Washington).

The evidence for the solvate theory of solution, which has been furnished in this laboratory as the result of somewhat more than a dozen years of investigation, has recently been brought together, and briefly discussed (Zeit. Phys. Chem., 1910, lxxiv., 325). The evidence is so unambiguous and convincing that ions and some molecules combine with more or less of the solvent that it can now be accepted as a fact of science.

This, however, raises a number of questions, What relation does the solvate theory of solution bear to the theory of electrolytic dissociation?

Does the solvate theory help us to explain any of the apparant discrepancies in the theory of electrolytic dissociation? Does the solvate theory help us to explain the facts of chemistry in general and of physical chemistry in particular? Why is the nature of solution so important, not only for chemistry but for science in general.

The Solvate Theory and the Theory of Electrolytic
Dissociation.

When Arrhenius proposed the theory of electrolytic dissociation the question was not even raised as to the condition of the ions in the solution except that they behave as if they existed independent of one another in solution. The theory simply said that molecules of acids, bases, and salts in the presence of a dissociating solvent like water break down to a greater or less extent into charged parts called ions; the cations or positively charged parts being electrically equivalent to the anions or negatively charged parts. The cations are usually simple metallic atoms carrying one or more unit charges of positive electricity. The cation might, however, be more or less complex, as illustrated by ammonium and its substitution products. The anion is usually complex, consisting of a larger or smaller number of atoms. It may, however, be an atom carrying negative electricity as in the case of the halogen acids and their

salts.

The degree of dissociation is determined by the nature of the acid, base, or salt. Strong acids and bases are greatly dissociated. Indeed, the degree of dissociation determines their strength. Nearly all of the salts are strongly dissociated compounds; there being, however, some exceptions, as, notably, the halogen salts of mercury, cadmium, and zinc. There are, however, considerable differences in the amounts to which salts in general are dissociated at the same dilution.

The quantitative evidence furnished by Arrhenius and others for the theory of electrolytic dissociation is so convincing that few chemists of any prominence who have carefully examined the evidence have ever doubted the general validity of the theory, and the theory has become substantiated by such an abundance of subsequently discovered facts that it has now become a law of nature and a fundamental law of chemical science.

Arrhenius saw and pointed out clearly the importance of ions for chemistry, and Ostwald and his pupils have shown that chemistry is essentially a science of the ion, molecules for the most part being incapable of reacting chemically with molecules, and Nernst has shown that the ion is the active agenti n all forms of primary cells.

The theory of electrolytic dissociation, as already stated, does not raise the question as to the relation between the ion and the solvent. At the time that the theory was proposed chemists did not know, and probably had no means of finding out, whether the ion is or is not combined with

* American Chemical Journal, 1911, xlv., 146.

Some of the many lines of evidence that ions and certain molecules are combined with a larger or smaller number of molecules of the solvent, and in many cases with a very large number of molecules of the solvent, as has already been stated, have recently been discussed briefly by myself in an article in the Zeitschrift fur Physikalische Chemie ("Evidence Obtained in this Laboratory during the Past Twelve Years for the Solvate Theory of Solution," Zeit. Phys. Chem., 1910, lxxiv., 325).

The amount of the solvent combined with an ion is primarily a function of the nature of the ion or ions in the solution. It is, however, conditioned very largely by the dilution of the solution and also by the temperature. The evidence, some of which is given in the paper referred to above, and the remainder in other publications, of the results of investigations carried out in this laboratory during the past dozen years, shows that the power of the ions to combine with the solvent is by no means limited to water and aqueous solutions, but is a property of solutions in general ("Conductivity and Viscosity in Mixed Solvents," by H. C. Jones and co-workers; Carnegie Institution of Washington, Publication No. 80). The alcohols, acetone, glycerol, &c., combine with certain substances dissolved in them, and it seems more than probable that all solvents combine with the dissolved substances to a greater or less extent. In a word, we do not have simply a theory of hydration, but a theory of solvation in general, which is an essential part of any generalisation which would take into account the facts presented by solution.

The solvate theory of solution has been regarded in some cases as a rival of the electrolytic dissociation theory of solution, if not directly antagonistic to it. Such is not at all the case. The solvate theory begins where the theory of electrolytic dissociation ends. The latter gives us the ions from molecules, and the former tells us what is the condition of the ions in the presence of a solvent after they are formed.

The solvate theory of solution, then, simply supplements the theory of electrolytic dissociation, and both must be taken into account if we ever wish to understand the phenomena presented by solution.

Does the Solvate Theory Help to Explain any of the Apparent Exceptions to the Theory of Electrolytic

Dissociation ?

Given the theory of solvation in solution together with that of electrolytic dissociation, the first question that arises is, does the former really aid us in explaining the phenomena presented by solutions?

Shortly after the theory of electrolytic dissociation was proposed, it was recognised and repeatedly pointed out that after all it is only a theory of "ideal solutions"; i.e., very dilute solutions. It was shown not to be able to explain many of the phenomena presented by even fairly concentrated solutions. Indeed, it often could not deal quantitatively with the very solutions with which we work in the laboratory.

The explanation of this shortcoming was not fully seen, and an analogy was resorted to. It was pointed out that the laws of Boyle and Gay-Lussac for gases hold only for "ideal gases," i.e., dilute gases, but do not hold for any gases of considerable concentration.

It was stated that the gas laws when applied to solutions could not be expected to hold more generally than when applied to gases, and there the matter was allowed to rest. In the early days of the theory of electrolytic dissociation it was, however, pointed out that we have a fairly satisfactory explanation of why the simple gas laws do not hold for concentrated gases, and this was expressed in the equation of Van der Waals, while no analogous explanation was offered in the case of solutions.

That this point was well taken is obvious to anyone. A theory of solution to be of the greatest value must be

The explanation of these apparent exceptions to the theory of electrolytic dissociation presented by concentrated solutions has been furnished by the solvate theory. We now know that for solutions in general a part of the solvent is combined with the dissolved substance. While the amount of the solvent combined with any one ion is greater the more dilute the solution, at least up to a certain point, the total amount of the solvent in combination with the dissolved substance is greater the more concentrated the solution.

That the amount of combined solvent may become very great, even relative to the total amount of solvent present, can be seen from the following facts: In a normal solution of calcium chloride about two-fifths of the total water present is combined with the dissolved substance. In a three normal solution of calcium chloride about fivesevenths of the total water is combined.

In the case of a normal solution of aluminium chloride in water about five-eighths of the water present is combined with the dissolved substance, while in a two normal solution about five-sixths of the water present is in a state of combination ("Hydrates in Aqueous Solution," by H. C. Jones and co-workers, Carnegie Institution of Washington, Publication No. 60).

What we suppose to be a normal solution of calcium chloride is therefore more than one and one-half times normal, while what we suppose to be a three normal solution is in reality more than eight times normal. In the case of aluminium chloride what we suppose to be a normal solution is more than twice normal, while what we prepare as a twice normal solution is about twelve times normal.

These few facts taken from thousands of a similar character show that even fairly concentrated solutions are much more concentrated than we would suppose from the method of their preparation, while very concentrated solu. tions are many times more concentrated than without the facts of solvation we should be led to think.

The general conclusion is that even fairly concentrated solutions are much stronger than if no solvation occurred, and are much more concentrated than we are accustomed to consider them from the amount of substance added to a given volume of the solution-more or less of the water present being in combination and only the remainder playing the role of solvent. Without the theory of solvation we have hitherto regarded all the water present as playing the role of solvent.

We should therefore not expect the laws of gases to apply to such solutions when we had no idea what their true concentration was. Now that we know their concentration we find that the laws of gases are of as general applicability to solutions as to gases, holding not simply for dilute solutions, but also for concentrated.

The theory of electrolytic dissociation, supplemented by the theory of solvation, is then not simply a theory of dilute or "ideal" solutions, but a theory of solutions in general.

Does the Solvate Theory Aid us in Explaining the Facts of Chemistry in General and of Physical Chemistry in Particular?

To answer this question at all fully would lead us far beyond the scope of this paper. A few facts bearing upon this question can, however, be taken up. Take, for example, the action of the hydrogen ion, both in the formation and the saponification of esters. In the presence of the alcohols the hydrogen accelerates greatly the velocity with which an ester is formed, while in the presence of water it causes the ester to break down into the corresponding acid and alcohol.

In terms of ordinary chemical conceptions it is difficult, not to say impossible, to interpret these reactions-the hydrogen ion under one set of conditions undoing what under other conditions it effected.

In terms of the solvation theory these reactions admit of a very simple interpretation. While the hydrogen ion is not strongly solvated, yet work in this laboratory has shown that all ions are more or less solvated. In the presence of alcohol the hydrogen ion therefore combines with

a certain amount of this solvent. The hydrogen ion plus the alcohol combined with it unites with the organic acid, forming complex alcoholated ions, which then break down forming the ester.

On the other hand, the hydrogen ion in the presence of water combines with a certain amount of this solvent. The hydrated hydrogen ion together with the water united with it combines with the ester, forming a complex hydrated ion, which then breaks down into the corresponding acid and alcohol, setting the hydrogen ion free again.

For a fuller discussion of this reaction see the paper by E. Emmet Reid (Am. Chem. Fourn., 1909, xli., 504). A reaction analogous to the above is that of hydrogen ions on amides in the presence of water, on the one hand, and of alcohol on the other. In the presence of water the hydrated hydrogen ion combines with the amide, forming complex hydrated ion, which then breaks down, yielding ammonia and acid, the ammonia, of course, combining with the acid. In the presence of alcohol the alcoholated hydrogen ion combines with the amide, forming a complex alcoholated ion, which then breaks down into ammonia and the ester of the acid in question.

Hydrogen ions in a mixture of water and alcohol, which would contain both hydrated and alcoholated hydrogen ions, give both reactions simultaneously; but as Reid has pointed out, in the presence of an equal number of molecules of water and alcohol, the tendency of the hydrogen ion to hydrate is greater than the tendency to form alcoholates, and under these conditions the first reaction proceeds relative to the individual reactions much more rapidly than the second (Am. Chem. Journ., 1909, xli., 509).

A very large number of types of reactions could be discussed illustrating this same point; i.e., the value of the solvate theory in interpreting chemical reactions.

When we turn to physical chemical processes the solvation of the ions has to be taken into account at every turn. The velocities of the ions are, of course, a function of the degree of their solvation, and the behaviour of the ions both chemically and physically is a function of their velocities. The effect of dilution, and especially of temperature, on reaction velocities is largely a question of the velocities of the ions present, which in turn are a function of the degree of their solvation.

In determining the actual concentration of a solution the amount of the solvent combined with the ions must be taken into account, as has already been pointed out, and without knowing the actual concentrations of solutions quantitative chemistry would be impossible.

The solvate theory has thrown a flood of light on the whole subject of the conductivity of solutions, or the power of the ions to carry the electric current. It has shown us why the conductivity of lithium salts is less than that of sodium and potassium, notwithstanding the fact that the lithium ion is much smaller and lighter than the atom of sodium and potassium. We now know that the lithium ion is much more hydrated than the ions of sodium and potassium, and the mass of the moving ion is really much greater than that of sodium or potassium.

When we come to the temperature coefficients of conductivity, the solvate theory has enabled us to interpret results which, without its aid, would be meaningless. We now know why ions with the greater hydrating power have the larger temperature coefficients of conductivity. We know why ions with the same hydrating power have approximately the same temperature coefficients of conductivity, and why more dilute solutions have larger temperature coefficients of conductivity than more concentrated (Jones, Am. Chem. Fourn., 1906, xxxv., 445), and we could

127

multiply examples almost without limit, did space permit, of the effect of the solvate theory on physical chemistry.

Why is the Nature of Solutions of such Vital importance not only for Chemistry but for Science in General? The fact is well recognised that modern physical chemistry has reached out into nearly every branch of science, and has had an important influence on many of them. The question arises, Why is this the case? The answer is that physical chemistry is primarily a science of solutions.

This answer may not at first sight appear to be selfevident, but a moment's thought will show its general correctness. The whole science of chemistry is primarily a science of solutions in the broad sense of that term. By solutions is meant not simply solutions in liquids as the solvent but solutions in gases and in solids as well, and not simply solutions at ordinary temperatures but also at elevated temperatures.

If we think of chemical reactions in general we will realise what a small percentage of them take place out of solution. Therefore the nature of solution is absolutely fundamental for chemistry. This applies not simply to general chemistry, including the chemistry of carbon, but also to physiological chemistry, which deals almost entirely with solutions in one solvent or another.

When we turn to physics we find solutions not playing as prominent a rôle as in chemistry, but, nevertheless, coming in in many places. The primary cells, secondary cells, electrolysis, polarisation, diffusion, viscosity, surfacetension are all phenomena in which the physicist is interested, and all depend for their existence upon

solution.

When we turn to the biological sciences we find that solution is almost as important as for chemistry. Take physiology; here we have to deal very largely with solution in the broad sense of the term. The same remark applies to physiological botany, and solutions are very important for both animal and vegetable morphology, especially in their experimental developments. Bacteriology is fundamentally connected with solutions, and pharmocology is based upon solutions either without or within the body of the animal.

Solution in the broad sense is as fundamental for The igneous rocks were solugeology as for chemistry. tions of one molten mass in another, and sedimentary deposits came down for the most part from solutions in water. The minerals crystallised out from solutions, and solutions of various substances, such as carbon dioxide, are to-day weathering the rocks and continually changing the appearance of the face of the globe.

An examination of facts such as those referred to above will show the truth of the statement that the relation of

physical chemistry to solutions is the prime reason why physical chemistry is so closely related to so many other branches of natural science.

This alone would show the importance of a true and comprehensive theory of solutions, not alone for physical chemistry but for the natural sciences in general.

Physical Chemistry Laboratory, Johns Hopkins University, October, 1910.

Royal Institution.-On Tuesday next, March 21, at 3 o'clock, Dr. M. Aurel Stein delivers the first of a course of three lectures at the Royal Institution on Explorations of Ancient Desert Sites in Central Asia." The Friday Evening Discourse on March 24 will be delivered by Sir David Gill on "The Sidereal Universe," on March 31 by Prof. H. S. Hele-Shaw, on "Travelling at High Speeds on the Surface of the Earth and Above it," and on April 7 by Prof. Sir J. J. Thomson, on "A New Method of Chemical Analysis,"

ROYAL SOCIETY,

Ordinary Meeting, February 23rd, 1911.

Sir ARCHIBALD GEIKIE, K.C.B., President, in the Chair. PAPERS were read as follows:

"Transmission of Flagellates living in the Blood of certain Freshwater Fishes." By Miss M. ROBERTSON, M.A. "Report on the Separation of Ionium and Actinium from certain Residues, and the Production of Helium by Ionium." By B. B. BOLTWOOD, Ph.D.

At the end of 1907 the Royal Society lent to Prof. Rutherford certain actinium residues, which were part of the material remaining after the separation of the radium by Messrs. Armet de Lisle, of Paris, from uranium residues acquired by the Royal Society. These residues, in weight 20 kilogrms., contained a large quantity of lead, and were a very heterogeneous mixture of elements. A preliminary examination made by Prof. Rutherford showed that actinium was present, and also a small quantity of radium. The amount of ionium, however, was much less than the theoretical amount to be expected if all of it had been removed with the actinium. The preliminary work of concentration was done by Messrs. Tyrer and Co., under the direction of Prof. Rutherford and Mr. Greenwood. This material was given to the writer for further concentration, and the paper contains an account of the methods employed in the separation of the actinium and ionium.

The ionium was finally obtained mixed with 1-8 grms. of thorium oxide. The activity of this oxide, due to the ionium it contained, was about 3000 times that of an equal weight of uranium oxide. By counting the a-particles from a thin film by the scintillation method, the amount of ionium present with the thorium was found to be equal to the amount in equilibrium with 5'3 mgrms. of radium in a radio-active material. The actinium was finally con centrated to about ro grms. of material, which gave a final activity about 20,000 times that of uranium oxide. It was estimated that the amount of actinium separated was equivalent to the amount in equilibrium with 30 mgrms. of radium in a mineral.

Special experiments were made to test whether ionium was transformed into helium. The presence of helium was determined by its spectrum, and the volume produced was measured. The investigation showed that helium is produced by ionium as well as by all other products which emit a-rays.

"Secondary Rays produced by B-Rays." By J. A. GRAY, B.Sc.

Secondary y-rays are produced in different materials by the B-rays of RaE, the greater in amount the greater the

atomic weight of the radiator. The y-radiation observed

from a preparation of RaE can be greatly increased by a suitable disposition of the active matter and apparatus.

"Specific Heat of Water." By W. R. BOUSFIELD, M.A., K.C., and W. ERIC BOUSFIELD, B.A.

The object of this investigation was to obtain a basis curve for the specific heat of water, for comparison with specific-heat curves of aqueous solutions. Former observers using different methods have obtained widely varying curves; thus for the specific heat of water at 80° in terms of the 150 calorie, the following figures have been given, showing differences of I per cent :-Barnes, 10014; Regnault, 10081; Lüdin, 10213.

For the value in joules of the 15° calorie the following have been found: -Joule, 4'174; Griffiths, 4'198; Barnes, 4.184.

The first part of our investigation is concerned with the determination of the mechanical equivalent of heat in terms of the mean calorie from 13° to 55°, by a method of con

I

NEWS

tinuous flow calorimetry. Mercury thermometers were used which could be read to o'005°. An interval of 40° was taken, so that an error of o'or° would not vitiate the result by more than I in 4000. Through a Dewar vessel containing about 3 litres of water, in which was an electric heater, there was passed a current of water, entering at about 13° and passing out at about 55°. The vessel was immersed in a bath kept at same temperature as contents of vessel. The top of the vessel was closed by a platinum box kept 10° higher.

The electric heater, and the resistance used in series with it for determining the current by help of a battery of standard cells, were of novel type. Each consisted of a spiral glass tube of small bore into the ends of which are sealed platinum electrodes. The tube is connected with a thermometer tube so that the spiral forms a thermometer bulb. By calibrating the resistance against the reading of this thermometer tube, the resistance is accurately known, even when a current is passing. This type of resistance enabled us to surmount a difficulty apparently never considered by previous investigators. We have found that when a heavy current passes through an ordinary standard resistance, the resistance of the standard depends not only on temperature but also upon strength of current. This effect may be conveniently called the "thermoid" effect. We believe a liquid mercury resistance is free from any such effect.

The continuous flow experiments gave for distilled water Jis = 4·182. To get the curve for J from o° to 80°, a weighed quantity of water was heated from o° to 80° by stages which gave J JJ Jo, the mean specific heats over the intervals. For this purpose the capacity of the calorimeter was obtained from the value of Jis previously determined, and a separate research on the specific heat of glass was carried out in order to obtained the variation of capacity with temperature. From these an equation for the value Je was obtained, and then the value of J from point to point, from the equation

We thus obtain J = 4 2085-00030220 +0.000078330* -0.00000049008, which gives for the value of the 15° calorie 4 179. The resulting curve corresponds closely with that obtained by Lüdin by the method of mixtures, and differs considerably from that obtained by Barnes by continuous flow with platinum thermometry.

"Measurement of Specific Inductive Capacity." Prof. C. NIVEN, F.R.S.

By

The paper contains an account of work undertaken to determine the specific inductive capacity of liquids by the method of resonance. charge of condensers with air and with liquid as dielectric The frequencies of the diswere compared by the cymometer and dielectric constants of the liqulds deduced. With some liquids, notably with the liquid. water, the question is complicated by the conductivity of

The conditions of discharge through a conducting liquid are therefore first determined, and the condition of resonance between the two resonating systems found. This is shown to be of a simple character, reducing practically to what it would be if the conduction through the liquid were neglected.

In some cases, water for example, it is impossible to set up oscillations directly; but by interposing in the circuit of the condenser another of considerable capacity, the oscillations may be obtained. When the capacity of this interposed condenser is relatively very large, it has no appreciable effect on the frequency of the oscillations produced, which are thus those of the liquid condenser alone.

Owing to the rapid variation of the specific inductive capacity with temperature, special arrangements had to be made to keep the liquid at a constant temperature while measurements were being made. The results of a number of determinations at different temperatures are given for water and alcohol,