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collaboration with Mr. Ramage, a large number of these complicated spectra were photographed at the North-Eastern Steel Works, where the Thomas-Gilchrist process is carried out. The spectra were fully described and measured, with the result that every one of the lines and bands was accounted for. A new line belonging to potassium was discovered to have peculiar properties. Gallium was proved to be present in the Cleveland ore from Yorkshire, in the finished metal, in clays and in all aluminous minerals, even in corundum. Also, by very accurate determinations of the wave-lengths of its principal lines, gallium was proved to be a constituent of the sun. Moreover it was found in several meteorites. Pure gallium oxide was separated, by analytical methods, from iron ores and other materials; and the proportion of the metal in the steel rails made by the North-Eastern Steel Company, of Middlesbrough, was determined and found to be one part in thirty thousand. This Yorkshire steel is richer in gallium than any other substance from which it has been extracted; for instance, the Bensburg blende, supposed hitherto to be the richest ore, contains only one part in fifty thousand.

By observations on the spectra, the thermo-chemistry of the Bessemer process of steel manufacture was studied, and the temperatures attained under varying conditions were estimated. The demonstration of the great volatility of most metals, and of many metallic oxides in an undecomposed condition, at the temperature of the oxyhydrogen blowpipe and of the Bessemer flame was of special interest. The metals chiefly referred to are copper, silver, lead, tin, manganese, chromium, iron, cobalt, nickel, palladium, gold, and iridium. Several of these, such as silver and gold, have lately been distilled in vacuo by Krafft.

Banded Flame Spectra.

Well-defined a similar constitution; thus magnesium, zinc, and cadmium yield bands composed of groups of elements yield banded flame spectra which have fine lines, degraded towards the violet, while fluted band spectra of beryllium, aluminium, and indium were found to be degraded towards the red. Thallium also yields a fluted spectrum; gallium gives a line spectrum; lanthanum gives bands degraded towards the red; palladium gives bands in the nature of flutings composed of fine lines; germanium gave very faint indications of bands; rhodium and iridium both lines and bands. It became manifest that elements belonging to the same group in the periodic system of classification exhibited banded spectra which are similarly constituted, and hence similarly constituted molecules of the elements have similar modes of vibration, whether at the lower temperature of the flame or at the higher temperature of the arc or spark. Banded spectra are thus shown to be connected with the periodic law.

A great advantage is to be derived from an investigation of banded spectra from a theoretical point of view, as well as from the application of this method to the analysis of terrestrial matter. applied in a very simple manner to the chemical analysis of minute quantities of While the spectra are easily obtained, they can be material, and may readily be made quantitative.

M. Ármand de Gramont has described a method of obtaining spectra of metals and metalloids by means of a spark, and has given the analysis of eightysix mineral species. The novelty and importance of his work lies in the method of obtaining spectra of such constituent substances as chlorine, bromine and iodine, sulphur, selenium and tellurium; also phosphorus and carbon when in a state of combination, as sulphates, phosphates, carbonates, &c.

There is a possibility of utilising this method for the quantitative determination of carbon, sulphur, and phosphorus in iron and steel during the process of manufacture.

Definition of an Element.

In a discussion on the question of the elementary character of argon in 1895 it was pointed out by me that argon gave a distinct spark spectrum by the action of condensed sparks, and therefore, on this evidence alone, it must be regarded as an element. The fact that it gave two spectra under different conditions was not

opposed to, nor did it invalidate, this evidence, because such an element as nitrogen not only emits two spark spectra, but the two spectra can be readily photographed simultaneously from the same spark discharge.

It was proposed by M. de Gramont at the International Congress in Paris in 1900, and agreed, that no new substance should be described as an element until its spark spectrum had been measured and shown to be different from that of every other known form of matter.

This appears to me to have been one of the most important transactions of the Congress. The first application of this rule has resulted in the recognition of radium as a new element: it is characterised by a special spark spectrum of fifteen lines which have been fully studied and measured by Demarçay. It shows no lines of any other element.

Another application of this rule has recently been made by Exner and Haschek with preparations of the oxide of an element obtained by Demarçay, and named europium. It exhibits 1193 spark lines and 257 arc lines.

I have already mentioned that one feature strikingly shown in the spectra of chemically related elements was the wider separation of the lines in pairs, triplets, or other groups; and that this was in some way related to the atomic mass, since the separation was greater in those elements whose atomic weights were greater. Kayser and Runge, and also Rydberg, have shown that in the series of alkali metals the atomic weights are very nearly proportional to the squares of the differences between the oscillation frequencies of the lines, that is to say, the squares of the intervals between the lines. Runge and Precht have recently shown that in every group of elements that are chemically related the atomic weight is proportional to some power of the distance separating the two lines of the pairs of which the spectrum is constituted. In other words, if the logarithms of the atomic weight and distance between the lines be taken as coordinates the corresponding points of a group of elements which are chemically related will lie on a straight line. Applying this law to the determination of the atomic weight of radium they find that the strongest lines of the new element are exactly analogous to the strongest barium lines, and to those of the closely related elements magnesium, calcium, and strontium. The intervals between the two lines of each pair in the principal series, and in the first and second subordinate series, if measured on the scale of oscillation frequencies, are equal for each element, and the same law holds good for the spectrum of radium. From this the value 257-8 was found for the atomic mass of the element. This does not quite accord with the number obtained by Madame Curie, who found it to be 225. It will be interesting to see which number will eventually be proved to be the more correct.

It is now many years since I first pointed out that the absolute wave-lengths of the lines of emission spectra of the elements are physical constants of quite as great importance in theoretical chemistry as the atomic weights; in the light of recent discoveries this statement may be said to be now fully justified.

Radio-active Elements.

From the study of rays of measurable wave-lengths we have lately sailed under the guidance of M. Henri Becquerel into another region where it is doubtful whether the rays conform to the undulatory theory. In fact the rays are believed to be charged particles of matter, charged, that is to say, with electricity. Beyond doubt they are possessed of very extraordinary properties, inasmuch as they are able to penetrate the clothing, celluloid, gutta percha, glass, and various metals. They are, moreover, endowed with a no less remarkable physiological action, producing blisters and ulcerations in the flesh which are difficult to heal. It is an established fact that such effects have been caused by only a few centigrams of a radium compound contained in a glass tube enclosed in a thin metallic box carried in the pocket.

From this we can quite understand that there is no exaggeration in the statement attributed to the discoverer, Professor Curie, by Mr. W. J. Hanmer, of the American Institute of Electrical Engineers, that he would not care to trust

himself in a room with a kilogram of pure radium, because it would doubtless destroy his eyesight, burn all the skin off his body, and probably kill him.

It remains for me to express regret that without an undue extension of the time devoted to this Address it would have been scarcely possible to afford adequate treatment to the absorption spectra of inorganic compounds, particularly those of the rare earths, and such also as afford evidence of the chemical constitution of saline solutions; or of organic compounds closely related to coloured substances and dyes, the investigation of which leads to the elucidation of the origin of colour, and serves to indicate the nature of the chemical reactions by which coloured substances may be evolved from those which are colourless.

Chemistry is popularly known as a science of far-reaching importance to specific arts, industries, and manufactures; but it occupies a peculiar position in this respect, that it is at one and the same time an abstract science, and one with an everincreasing number of practical applications. To draw a line between the two and say where the one ends and the other begins is impossible, because the theoretical problem of to-day may reappear upon the morrow as the foundation of a valuable invention.

The following Papers and Reports were read:—

1. Apparatus for Determining Latent Heat of Evaporation.
By Professor J. CAMPBELL BROwn, D.Sc.

The apparatus exhibited furnishes a direct method of determining the latent heat of evaporation, at the boiling point, of any volatile substance of which something approaching 50 grammes can be obtained. None of the substance is lost, and no comparison with any other substances is required. The amount evaporated is accurately weighed and the amount of heat employed in evaporating it is accurately measured.

From 15 to 20 grammes of the substance are placed in a tube about 10 cm. long and 23 mm. wide, which is closed at one end and drawn out at the other end to an orifice 1.5 mm. wide. The tube contains in its lower third a spiral of fine platinum wire welded at its extremities to thick platinum wire terminals. These terminals pass through the bottom of the tube and dip into mercury contained in U-shaped projections from the expanded neck of a flask of 30 to 50 c.c. capacity. This tube is heated to the boiling point of the liquid in the manner about to be indicated and is then closed temporarily by a cap and carefully weighed. It is then replaced in the flask. A glass cap is ground on to the neck of the flask, and is provided with an orifice through which vapour can escape into an outer jacket. The space between the tube and the cap and neck of the flask forms the inner jacket. A long glass cap having an escape tube for the condensed liquid is fixed over the whole expanded neck of the flask by means of a ring of cork or indiarubber.

A convenient quantity of the liquid is placed in the flask and boiled by a suitable bath. Its vapour passes into the jacket above and raises the temperature of the tube and its contents to the boiling point of the liquid. When the weighed tube and its contents have been replaced and the temperature is constant, a current of electricity is passed through the spiral by means of the mercury in the U-tubes. The time is noted and an ammeter in the circuit is watched and recorded every two minutes. A voltmeter is also switched into the circuit every two minutes and read. At the end of, say, twenty minutes, the average ampères and volts are recorded. From these data the heat expended in evaporation is calculated. The tube is taken out and re-weighed to ascertain the weight of substance evaporated by this quantity of heat. The double jacket of its own vapour keeps the tempe rature constant at the boiling-point and prevents loss of heat into the room.

The ammeter and voltmeter should be accurate to at least of the total reading employed; and must therefore be more accurately calibrated than are the best instruments usually supplied by the trade.

The first experiments should be rejected. With practice the results are accurate and the method easy. The variations in different experiments by different operators are usually a small decimal figure.

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2. On some Derivatives of Fluorene. By Miss IDA SMEDLEY.

3. Action of Diastase on the Starch Granules of Raw and Malted Barley. By ARTHUR R. LING, F.I.C.

The whole of the published data referring to the hydrolysis of starch by diastase have been derived from the study of the action of the enzyme on potatostarch paste, and the application of these to practical purposes has led to misleading and erroneous conclusions. The starches of barley and other cereals differ from that of the potato in being readily attacked by a solution of diastase in the ungelatinised condition.

The author has carried out a series of mashes with barley and malt starch of various origin, the starch being mixed with the diastase preparation in the dry state and mashed with water at different temperatures for two hours. The following table illustrates the results obtained :

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* The symbol R denotes the percentage of apparent maltose, determined by the cupric reduction method, on the dissolved matter in solution. The symbols [a]D 3.93 and R 3.93 indicate that the total solids have been calculated from the specific gravity of the solution by the divisor 3.93.

The very great differences between the constants yielded by the starch mashes and the starch paste conversions are apparent. It is also to be noted that the starches from different barleys give different constants, and the author hopes to continue his work in this direction. He brings forward evidence showing that in the process of mashing, as conducted in breweries, the starch granules are dissolved directly by the diastase and are not gelatinised prior to hydrolysis, as it is usually stated they are. It is probable that the products formed in these starch mashes are different from those resulting from the hydrolysis of starch paste; and it is hoped that a study of the former may yield results of both theoretical and practical importance.

4. Action of Malt Diastase on Potato-starch Paste.

By ARTHUR R. LING, F.I.C.

Brown and Millar have shown that the so-called stable dextrin-one of the products of the hydrolysis of potato-starch paste by diastase—is converted by the further action of diastase into a mixture of about equal parts of d-glucose and maltose. The observation of Davis and Ling (next abstract), that no d-glucose is formed when unrestricted diastase acts on starch paste, stands in apparent antithesis to this. However, the author has confirmed the result of Brown and Millar, and has found further that other isolated products of diastatic action yield a proportion of d-glucose when submitted to the further action of unrestricted diastase; thus the maltodextrin, a of Ling and Baker, when treated in 3 per cent. solution with an active preparation of diastase at 55° for 140 hours, gave the constants [a]D 3.93 127·6°, R3·93 105-6, corresponding approximately with maltose 90 per cent., d-glucose 10 per cent. The presence of 10-5 per cent. of d-glucose in the product was proved by weighing the phenylglucosazone formed under standard conditions. Taking into account the fact that potato-starch paste is never completely converted into maltose, although the final product has the constants of that sugar, and that a substance is always present which is identical with the isomaltose of C. J. Lintner, the simple dextrin of Ling and Baker, and the dextrinose of Syniewski, which when isolated and submitted to the action of diastase yields d-glucose, the author suggests that the reason no d-glucose can be detected among the products of the action of unrestricted diastase on starch paste is that that sugar is immediately condensed by the action of the enzyme forming dextrinose. When, however, diastase is preheated, its condensing action is weakened, and the d-glucose formed can be isolated. Attempts to condense d-glucose or mixtures of it with maltose have not been successful.

5. Action of Malt Diastase on Potato-starch Paste.
By BERNARD F. DAVIS, B.Sc., and ARTHUR R. LING, F.I.C.

In a previous paper it was shown that when malt diastase is heated in aqueous solution above the temperature at which the activity of the enzyme is at its optimum, namely 55°, the reaction with potato-starch paste at about 55° is not only slower, but different products are formed; thus d-glucose can be readily isolated from them after the reaction has been allowed to proceed for several hours. Special experiments, employing the same quantities of diastase which has not been heated in solution above 55°, show that d-glucose is not formed either from starch paste or from maltose. It therefore appears that the production of this sugar is connected with the preheating of the hydrolytic agent in solution above 55°. As a result of a very large number of new experiments, which will be published shortly, the authors have arrived at the following conclusions.

Journ. Fed. Inst. Bren. 1902, 8, 475.

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