2. To what specifications (however imperfect such specifications may be) the resulting changes may have to

conform.

3. To what extent impurities may mutually react to the improvement or detriment of the resulting material. The author has given special attention to the influences of oxygen and arsenic, whilst bismuth, lead, nickel, antimony, silicon, iron, phosphorus, manganese, &c., are all dealt with in turn.

The evidence of the microscope is called largely into requisition and the importance of various kinds of testing is emphasised.

ATTENTION was directed to the importance of making measurements of optical rotation over a range of wavelengths, instead of merely with light of one colour. This is specially necessary in the case of substances, such as derivatives of tartaric acid, in which anomalous rotatory dispersion is known or may be suspected to exist.

After experiments extending over a period or seven years, the methods of measuring rotatory dispersion have been so simplified that they are now within the range of the ordinary advanced student, and should soon become a regular part of the ordinary routine of the laboratory. For many purposes it is sufficient to take readings with the green and violet mercury lines, but sodium and lithium may also be used in order to see whether the curve of rotatory dispersion has the normal form. A still more valuable check is provided by readings taken with the red and green cadmium lines, but these require more complex apparatus and cannot yet be regarded as generally

available.

a

I. THERE are three different types of anomalous rotatory dispersion. The anomaly in question may be due: (a) To the superposition of two (or more) different kinds of normally dispersing molecules, differing in rotatory dispersive power as well as in the sign of their rotation. This type of anomalous dispersion was first established by Biot. (Ex. mixture of menthone and iso-menthone.) (b) To the existence of absorption bands in the spectrum of the active substance, as it has been pointed out by Cotton, Drude, and others. (Cotton's phenomenon.) (Ex. the xanthates and thiourethanes of menthol, borneol, and fenchol.) (c) To the intramolecular superposition of partial rotations corresponding to several centres of activity of one and the same molecule, as it has been shown first by the author. Experimental evidence in favour of this classification is given.

2. It has been established that the shape of the dispersion curve is largely influenced by constitutive factors, and in the first place by the relative position of the centres of activity and of the chromophor groups within the active molecule, the whole dispersion curve resulting from the superposition of several "partial" curves. These results are discussed from the point of view of the electronic theory.

the solvent on the rotatory dispersion of the optically 3. The influence of the temperature and the nature of active xanthates resembles closely the influence exerted by the same factors on the dispersion of tartaric acid and There must therefore be an intimate analogy in the origin of its ethereal salts as studied by Winther and others. of the anomaly in both cases.

RADIO ELEMENTS AS INDICATORS IN CHEMISTRY AND PHYSICS.* By G. HEVESY, Ph.D.

By means of an a-ray electroscope of ordinary sensitiveness it is possible to measure accurately as small a quantity as 10-17 grms. of a radio-active substance having a halfvalue period of one hour. The extraordinary simplicity and at the same time sensitiveness with which it is possible to measure these extremely small quantities of radio-active bodies makes them of the greatest use not only in studying substances in great dilution but also as indicators of physical and chemical processes.

Radio-active indicators may be conveniently divided into two principal groups. To the first group belong those whose use as indicators depends only on their physical properties and not on their chemical properties. Some

Read before the British Association (Section B), Birmingham

Meeting, 1913.

CHEMICAL NEWS,

Oct. 3, 1913

It is only necessary to know that the radio-elements composing the active deposits are metals in order to test the formula of Arrhenius connecting the variation of velocity of solution of metals in acids with the temperature. This has been lately carried out by Miss Ramstedt.

It is known from the kinetic theory that the concentration of a solution varies with time, and this problem, which could not be attacked by ordinary methods, has been made experimentally feasible by the use of radio-active bodies as indicators. (Svedberg, Smoluchowski).

The existence of colloidal solutions of radio elements has been lately established by Paneth and Godlewski, and experiments have been undertaken on the formation and precipitation of these colloids using radio-active indicators. The emanations, the only gaseous radio-elements, have been employed to establish the validity of the gas laws, especially that of Henry's law for extremely small partial pressures. (Bruhat, Boyle).

Fick's Diffusion Law has also been shown to hold accurately for bodies in infinitely small concentration by making use of radio-active substances.

It is often a question of practical interest to the chemist to know how often it is necessary to wash out a pipette or a beaker in order to remove the last trace of the solution it had contained. This problem can be investigated with extreme ease when radio-active indicators are used.

The fact, however, that most radio-elements are throughout in all chemical properties exactly similar to some of the common elements (for instance, radium D and thorium B are non-separable from lead, thorium C and radium E from bismuth, &c.) allows these bodies to be used chemically as indicators of the bodies from which they are known to be non-separable. Radium E can be used as an indicator for bismuth, radium D for lead, &c.

If I mgrm. of lead is mixed with a quantity of radium D which gives 10,000 units of activity in an electroscope, one-millionth part of this mixture is easily detectable by the radio-activity of radium D. In this way 10-mgrms. lead is quantitatively determinable.

By this method also the solubility of the difficultly soluble salts of lead, such as the chromate and the sulphide, has been determined. Further, the amount of lead chloride entrained by a precipitate of silver chloride after washing the latter thoroughly with water is measurable.

The variation of rotation with change in the colour o light, with change of solvent, with change of temperature, and perhaps even with change of pressure, must be thoroughly examined.

As regards the last little can be said, but the other three colour of light used, the nature of the solvent, and the temperature-are of the utmost importance. Even the data available at present seem sufficient to give some idea of the general behaviour of optically active compounds with changes of condition, and this may be summed up into one scheme, as follows:

It has been found that the rotation of certain active compounds reaches a maximum value at a certain definite temperature. Further, points of inflection often occur in temperature-rotation curves, sometimes in such as show also a maximum, and by piecing together the evidence collected from an examination of a fair number of optically active substances it seems probable that the variation of the rotation of an active substance with change of temperature may be, and very probably is, a periodic phenomenon, doubtless irregularly periodic-such that several maxima and minima may be expected to occur in the curve representing it. Owing to experimental difficulties, however, it is not possible to trace these curves through any very wide range of temperature.

Now it seems legitimate to assume that a point of maximum rotation indicates that condition of the substance in which one of the groups attached to the asymmetric atom attains to a maximum influence-a singular condition of the substance. When such singular points are found in the curves of condition for a number of fairly closely related compounds it seems reasonable to suppose that the maxima represent the rotations of these different compounds in, at least, fairly similar conditions. The great merit of a maximum rotation is its recognisability and the possibility it affords of tracing some particular state of the compound as the external conditions are varied. Maxima are found at different temperatures for the various members of a homologous series, but the discussion of this field, since it involves the relationship between the rotation and the constitution of a series of active compounds, may be passed over until the variation of rotation of a single active compound with change of external conditions is more fully understood.

means.

Of especial use are the indicators for investigating the diffusion and mobility of ions in extremely small concen. tration, from which results we obtain information concerning the behaviour and the hydration of ions in very dilute concentration. Data are already available on the diffusion rate of lead salts down to a normality of 10-14.

THE

ROTATION OF ACTIVE COMPOUNDS AS MODIFIED BY TEMPERATURE, COLOUR OF LIGHT, AND SOLUTION IN INDIFFERENT LIQUIDS.* By T. S. PATTERSON, D.Sc. Ph.D.

BEFORE it can be possible to offer a real explanation of the phenomena of optical activity, attention must be devoted to the lowlier task of trying to understand clearly the main features of the phenomena in question; to study carefully, in fact, what may be termed the morphology of the subject. Read before the British Association (Section B), Birmingham Meeting, 1913.

It is doubtful whether any substance will really show normal rotation-dispersion, but if such a substance be found then it seems probable that the temperature-rotation curves for the different colours of light will intersect at a single point, the rotation-dispersion being positive on one side of this point and negative on the other.

Rotation in Solution.-A study of such data as are available appears to show that when such a compound as shows a maximum rotation-for example, ethyl tartrateis dissolved in some indifferent liquid, this maximum rotation is displaced towards a lower or a higher temperature, as the case may be, with a corresponding alteration in value, solvents differing very much in regard to the displacement which they bring about. Now it is also found that the region in which abnormal rotation-dispersion takes place is shifted, on solution, in a very similar way to that in which the maximum rotation is displaced, and therefore it seems clear that the effect of solution is to displace the It then appears at crce whole temperature-rotation curve. why some substances which show abnormal repres

CHEMICAL NEWS, Oct. 3, 1913

TIMBER OF THE

ON THE

"COLONIAL BEECH "

(Gmelina Leichhardtii, F.v.M.).* By HENRY G. SMITH, F.C.S.

In all three schemes a new member was indicated in the V.A family, as the product of uranium X. This has since been discovered by Fajans and Beer (Naturwissen schaften, April 4, 1913), and confirmed by Fleck (Phil. Mag.). It proves to be a very short-lived substance of period of average life 17 minutes, and is called Uranium X2. Its parent, Uranium X1, with period 35'5 days, gives only the soft (8) rays, whereas the hard 3-rays of uranium X come from this new product.

This missing member being short-lived disproves the suggestion (Soddy) that it might be a very long-lived and and therefore well-defined element (Eka tantalum), disintegrating dually, and producing, in addition to uranium II. by a Bray change, actinium by a still undetected a-ray

change. This being disproved, the only other possibility to consider as to the still unknown source of actinium is that it is produced in a B-ray or rayless change from radium. On account of the uncertainty of the origin of actinium, and therefore of the atomic weight both of itself and of all its products, the actinium series is shown separately beneath the others in the plate.

The chemical analysis of matter is thus not an ultimate one. It has appeared ultimate hitherto, on account of the impossibility of distinguishing between elements which are chemically identical and non-separable unless these are in the process of change the one into the other. But in that part of the Periodic Table in which the evolution of the elements is still proceeding, each place is seen to be occupied not by one element, but on the average, for the places occupied at all, by no less than four, the atomic weights of which vary over as much as eight units. It is impossible to believe that the same may not be true for the rest of the table, and that each known element may be a group of non separable elements occupying the same place, the atomic weight not being a real constant, but a mean value, of much less fundamental interest than has been hitherto supposed. Although these advances show that matter is even more complex than chemical analysis alone has been able to reveal, they indicate at the same time that the problem of atomic constitution may be more simple than has been supposed from the lack of simple numerical relations between the atomic weights.

Hydrolysis of Levulosanes.-Ph. L. de Vilmorin and F. Levallois. In the hydrolysis of inulin sulphuric and oxalic acids gives results which are too variable to serve as a basis for a method of analysis. Acetic acid used at a temperature of about 80° and a concentration of 3 to 10 per cent is accurate, but as the temperature is raised the results obtained become rather too high. Very small quantities (0.72 to 4°3 grms. per litre) of sulphosalicylic❘ acid at temperatures varying from 80° to 100° give accurate results.-Bull. Soc. Chim. de France, xiii.-xiv., No.

13.

THIS Australian tree belongs to the Family Verbenaceæ, and is thus not a true "beech." The use of this common name for Gmelina Leichhardtii is an unfortunate one, as it really belongs to the genus Fagus of the Cupuliferæ. The tree is a native of New South Wales and Queensland, and grows to a considerable size, reaching to a height of 100 to 150 feet, with a diameter of over 3 feet. It is a useful commercial timber, light in colour, but with little or no figure, and thus cannot be classed as ornamental, although it is useful for carving and similar art purposes.

The seasoned timber often has white particles filling the cells of the wood, and these are sometimes so plentifully distributed that the planed surface has the appearance of having been filled, to a certain extent, with a substance like plaster-of-paris. When the timber is not sound this substance often accumulates in "shakes" and cracks of the wood as small opaque deposits, and in crystalline masses. Under the microscope these masses were seen to consist of needle crystals.

The presence of some substance in "beech," different from that of other native timbers, has previously been observed by saw-millers, and in a letter from Mr. W. Smith, of Tinnonee, New South Wales, he refers to this peculiarity as follows:-" Port Macquarie Beech contains something of a very cleansing nature. We have a planing machine, and dust from tallow-wood and other hard woods, but as and, of course, gets dirty, and stuck all over with sap

soon as we have put through a few beech boards, wherever the sappy chippings strike, the ironwork of the machine becomes clean and as bright as new."

Another saw-miller also mentioned that he had seen whitish deposits in "beech" timber, but thought them to be a fungoid growth.

The first well-defined deposit of this substance came into the possession of the Technological Museum a few years ago, and as much work as possible was, at that time, carried out with it, a crystalline body being isolated, and its melting-point determined. About two years later a small quantity was received from another locality, and similar crystals were again isolated from it, and found to be identical in appearance with the first, and to melt at the same temperature. Through the kindly assistance of Mr. Breckenridge, a Sydney timber merchant, a portion of a beech log in a very unsound condition was recently obtained from which a few grms. of pure crystals were extracted, sufficient to enable a more extended investigation to be undertaken.

The crystals obtained from all the trees from the various localities were colourless, odourless, and tasteless, and were identical in crystalline form, in melting-point, in optical activity, and exhibited the same peculiarity in the meltingpoints of the substance when in either the crystalline or the amorphous conditions. From this it is apparent that the deposit is a common constituent in the timber of this species of Gmelina, and also that it is a definite chemical substance. It is possible that it may be characteristic of this tree, or perhaps peculiar to the genus, and if so, its identification would become of some assistance towards correct diagnosis, especially as no other body appears to be present in the deposit which might contaminate it, and thus interfere with the ready isolation and purification of the crystals.

an

The peculiarity of this body in what appears to be perhaps example of dynamic isomorphism in a natural chemical

A Paper read before the Royal Society of New South Wales, November 6, 1912. From the Journal of the R. S. of New South Wales, 1912, xlvi., 187.

The following data will show how great were the differences between the melting-points of the crystals and those of the same substance after melting: :

(a) When the crystals were prepared by crystallisation from alcohol, or from boiling water, they were quite anhydrous, and melted at 122° C., to a transparent resinlike body, without alteration in weight. This fused material was, at first, strongly electric, and had the power of attracting light particles of filter paper, &c., very energetically. The melting point of this glassy substance had, by fusion, been reduced to 62–63° C., and so long as it remained in the glassy condition in the lump, the melting. point did not rise, even after many weeks, but if the fused substance was powdered the melting-point commenced to rise at once, and after a comparatively short time this had reached about 120-121°, but did not appear to revert quite to the melting-point of the original crystals.

(b) When the fused substance was powdered and the melting-point taken at once, this powder melted at the same low temperature as the spangles of solid material, but if the temperature was continually raised, when this had reached to about 100°, the melted substance became somewhat opaque, but reverted again to the transparent condition at the melting point of the original substance. (c) When the original crystals were boiled in water they softened and apparently fused at that temperature, and, when the solution had become saturated, remained as fused globules or masses in the boiling water, but soon solidified into a semi-crystalline condition when the water had sufficiently cooled, showing that complete fusion had not taken place, because when fused by dry heat the mass always remained as a glass, and there was no sign of crystallisation during the many weeks it remained under observation. If, however, this glass was dissolved in alcohol it again readily crystallised from this solvent, and the crystals were also readily formed from water when the glassy form was boiled directly in the usual way. When thus re-crystallised, the melting-point of the crystals, both from the alcohol and from the water, had reverted to that of the original crystals, although the melting-point of the fused material from which they had been derived had only been 62-63°.

(d) If the melted glassy substance was broken up into small spangles, but not powdered, these became, after several weeks, opaque and yellowish in colour. The meltingpoint of these opaque spangles had then considerably increased, showing that the tendency is to revert to the higher melting-point in all cases, which may thus be considered the stable condition. How many weeks or months it would take for the melted unbroken glassy lump to revert to the higher melting-point is not yet known, as sufficient time had not elapsed. So far, this has been found to be 62-630, and in one case three months had passed between the fusion of the substance and the determination of the melting-point. The method of observing the melting point of the spangles was to place them on a thin glass microscope slide cover-glass, to float this on mercury, and to observe the melting of the spangles with the aid of a lens. At near the melting-point the temperature was only allowed to rise very slowly.

The ready discoloration when bromine water was added to the saturated aqueous solution, with the formation of an insoluble bromide, indicated unsaturation, but this was not confirmed by an alkaline solution of potassium permanganate, as the colour of very dilute solutions remained apparently unchanged for a considerable time, although eventually oxidation to dimethylprotocatechuic acid took place. There appeared to be no alteration on an attempted reduction of the substance, when it was boiled with zinc in an acetic acid solution. The formation of the bromide was also found to have been by substitution, because when bromine was added to a solution of the crystals in carbon

One hydroxyl group was present in the side-chain, but no aldehydic group was formed even with mild reagents, the oxidation to a carboxyl group being direct. The action of concentrated halogen acids also indicated the presence of an alcoholic OH group, and bromine was introduced into the molecule when the substance was boiled in hydrobromic acid. The molecule contains two methoxy groups, and the acid formed by oxidation was veratric acid.

Neither an aldehyde nor carbonyl group was detected, nor were indications for the presence of an ester or of a glucoside obtained.

When fused with potash below 200° C., phenolic bodies were principally formed, but when the temperature was increased to about 225° the action became more energetic and the principal product was protocatechuic acid, a very small amount of a volatile acid being produced at the same time. The substance thus has a catechol nucleus.

When more material shall be obtained attempts will be made to determine accurately the arrangement of the atoms in the side-chain. The constitution of the remainder or the molecule is shown from the results.

The oxidation to veratric acid, the formation of protocatechuic acid on fusion with potash, the presence of one or more asymmetric carbon atoms, together with the other reactions, suggest a structural formula for this substance in agreement with that of several bodies found in plants, all related to a dihydric phenol, the OH groups of which are in the 3 and 4 positions.

The evidence so far obtained indicates that the crystalline substance which deposits in the timber of Gmelina Leichhardtii is new to science, and the name Gmelinol is proposed for it.

The molecule of gmelinol is C12H1404 and the formula may be arranged as follows:

The exact positions of the atoms in the side-chain have not been accurately determined, as they can be arranged, theoretically, in several ways. The one perhaps the most promising from general reactions, particularly the red and green colorations given by the vapour to pine-wood moistened with hydrochloric acid, is to consider the sidechain as consisting of furfurane. This is attached to the nucleus by the 3' carbon atom, the double bond broken, the valency completed by one hydrogen attached to one B-carbon atom, and a hydroxyl group to the other. The alternative structure for furfurane with only one double linkage answers to requirements better than the usually accepted form. If this arrangement is eventually found to be the correct one, then gmelinol is dimethyoxphenyl83'-hydro-oxyfurfurane, and has the following structure: