6 a.m. over England, and the partial phase at commencement will be some 3 minutes shorter than that after totality. The times mentioned in this lecture are G.M.T. The centre of the shadow cone makes first contact with the earth at 5H. 20.1M.. G.M.T., only 3 minutes before it reaches Cardigan Bay. At this point the diameter of the cone, where it intersects the earth is about 13.7 miles, and the distance of intersection from the imaginary point is about 1,500 miles. In the two succeeding minutes, when the intersection is near Hartlepool, the diameter increases to about 16 miles, corresponding to about 1,700 miles from the point. Owing to the low altitude of the sun, the intersection of the shadow cone with the earth's surface is a long ellipse. The minor axis of the ellipse is only about half of the 30 mile width of the shadow track, since the major axis of the ellipse is inclined at about 23° to its direction of motion. One result of these circumstances is that over the northern two-thirds of the shadow-track the approach of the shadow will appear to be from the E. of S. and not fro mthe S.W. The direction at Richmond will be about 15° E. of S. The apparent velocity will be considerably less than the velocity of travel.

PARTICULARS FOR RICHMOND, Yorks. The progress of the eclipse has been computed for the Race Course at Richmond, Yorkshire. The information includes the times of the four contacts and their position angles. The moon will first be seen to encroach on the sun at 4H. 30M. 37S. at angle of 293° from the vertex, that is, from the highest point of the sun as seen at that time and place. The angles are computed starting from North through East, to the left. The point is more conveniently found by considering it as 67° from the vertex counting towards the right.

The passage of the leading edge of the moon across the sun's disc takes about 54 minutes, the second contact, which is the commencement of totality, occuring at 5H. 24M. 39.9S. Totality is computed to last 22.8 seconds ending with third contact at 5H. 25M. 3.7S. The fourth contact, when the sun is finally clear of the moon, is about 57.5 minutes later.

THE OPTICAL SOCIETY.
June 9, 1927.

The Use of Photo-Electric Cells for the Photometry of Electric Lamps. By T. H. HARRISON, Ph.D., B.Sc., A.Inst.P.

A description is given of apparatus and

experiments designed for giving the highest accuracy and precision in the photometry of electric lamps using photo-electric cells. Although the methods adopted are not novel, yet every care has been taken to obtain the highest sensitivity in the photoelectric correct measuring apparatus and to maintain the lamps at a steady accurately known voltage voltage. It is claimed therefore, that the results are useful in showing the maximum capabilities of photoelectric cells when used in the usual manner with a sensitive electrometer or electroscope

The actual results are tabulated. A discussion is given of the sources of error to be expected, of the method by which they may be avoided, and of the computation of the accuracy of the results.

An Experimental Study of the Best Minimum Wave-Length for Visual Achromatism. By R. KINGSLAKE, A.R.C.S.,

D.I.C., M.Sc.

A special telescope is described, in which the chromatic aberration can be varied continuously by means of a zero-power lens sliding within the telescope tube, the conditions being such that this movement does not introduce any other underisable aberrations. This apparatus has been constructed, and by its aid many determinations have been made as to the best type of achromatism for visual observations, in daylight, in artificial light, and on astronomical objects. Several observers were employed to make settings, and their opinions as to the most desirable type of achromatism are tabulated and compared. In general it is found that a moderate amount of under-correction is needed to give a truly colour-free image, that less under-correction is required if the best definition is to be obtained, and that a slight over-correction is desirable for astronomical work.

On Brewster's Band. Part II. By SUSHIL KRISHNA DATTA, M.Sc., A.Inst.P.

This paper is a continuation of the one already published under the same title. It discusses the nature of the patterns obtained by the super-position of two systems of Haidinger's rings when the actual law of spacing of the rings is taken into consideration. Figures are reproduced illustrating the patterns, and a theoretical deduction of these is given.

THERMAL EXPANSION OF

GRAPHITE.

BY PETER HIDNERT AND W. T. SWEENEY. ABSTRACT.

This paper gives the results of an investigation on the thermal expansion of longitudinal and transverse sections of artificial graphite electrode (99.2 to 99.7 per cent. carbon) over various temperature ranges between room temperature and 600° C.

A summary of available data by previous observers on the thermal expansion of graphite (natural and artificial) and of other forms of carbon is included.

In the present investigation the coefficients of expansion of graphite were found to be low. The transverse samples expand considerably more than the longitudinal samples (approximately 45 per cent). For both the longitudinal and transverse samples the coefficients of expansion decrease slightly as the purity (carbon content) increases. The table in the summary gives a résumé of average coefficients of expansion derived from the data on all samples for various temperature ranges between 20 and 600° C.

SUMMARY.

The coefficients of expansion of graphite are low. For example, the coefficient of expansion of ordinary steel is about six times the coefficient of longitudinal sections of graphite and about four times the value for transverse sections between 20 and 100° C. The transverse samples expand considerably more than the longitudinal samples (approximately 45 per cent). The coefficients of expansion of all samples increase with temperature. For the longitudinal and transverse samples the coefficients of expansion decrease slightly as the purity (carbon content) increases.

BRITISH INDUSTRIES FAIR. Available exhibiting space for the 1928 British Industries Fair, at the White City, which has been leased also for the following two years, exceeds that provided last year by 100,000 square feet. Extensions amounting to 80,000 square feet are to be made at Birmingham. The schedule of exhibits at both centres has been slightly revised.

NOTICES OF BOOKS.

CHEMICAL TECHNOLOGY-PROBLEMS IN THE TEACHING OF THIS SUBJECT.

Unterrichtsprobleme in Chemie und chemischer Technologie im Hinblick auf die Anforderungen der Industrie. DR. WOLF JAMES MÜLLER. Published by by Julius Springer, Vienna. Pp. 17. Price 1 mark.

This pamplet is Dr. Müller's lecture given on the occasion of his taking up the post of professor of inorganic chemical technology at the Technical High School, Vienna.

Dr. Müller has got something to say but he gets up to page 14 before he says it. His long preamble is a historical re-statement of the position in Germany as regards chemical technical education, showing how that Germany in the past specialised on organic chemistry to the virtual exclusion of inorganic chemistry in its high schools, technical schools and universities, and how that this short-sighted policy was paid for during the Great War and afterwards (when the dye-monopoly was broken). Dr. Müller then goes on to explain that his idea of inorganic technical chemistry is in fact nothing more than chemical engineering, and he states that the present day system of training in German and Austrian technical schools produces persons who are regarded by chemists as engineers and by engineers as chemists, or as we should say "Jack of both trades but master of neither."

Present methods of training and present day opinion on those methods varies between two wide extremes. Manufacturers say, "Give chemists who are chemists and we will teach them the practical technical side of their work in our factories " whereas, some technical schools clamour for an additional period of training for students after qualifying for their degrees, but this training to be exclusively in factories or in laboratories on technological problems only. America has solved the problem by arranging for its technological students to work in factories during the vacations, and this system has been followed in Darmstadt where the technical high school has made arrangements for the training of students during vacation in the Darmstadt Gas Works.

The next problem is this :-What are we to regard as technical inorganic chemistry and how is it to be taught. Dr. Müller considers a definition of " chemical engin

(c) Separation processes.

(d) Reaction processes.

and each of these groups is divided according as to the materials are solids, liquids or gases and in the case of (c) and (d) as to the resulting components i.e., solid-solid; solid-liquid, solid-gas, liquid-liquid, liquidgas, gas-gas, and then further subdivision is obtained by separation of processes into mechanical heat processes, and electrical or magnetic processes.

The pamphlet will be of great interest to technical schools and modern chemical factories.

J. H. A.

James Blythe Rogers. By EDGAR F. SMITH. Pp. 14. Philadelphia. 1927.

Prof. Edgar F. Smith has done much to bring the lives of American chemists to public notice and his booklet on the life of James B. Rogers (1802-1852) will be widely read with the anticipation of sustained interest. In England many of the early American scientists are almost unknown, yot there were many who, like James Blythe Rogers, have given their contribution to the advancement of science.

He published several contributions dealing with analytical chemistry and many improvements in the manufacture of chemical products in America were due to him. J. G. F. D.

FORTHCOMING EVENTS.

ROYAL INSTITUTION.

21, Albemarle Street, W.1.

Monday, July 4, at 5 p.m.-General Meeting of the Members.

INSTITUTE OF CHEMISTRY OF THE AMERICAN CHEMICAL SOCIETY. The A. C. S. Institute of Chemistry will be held from July 4 to 30 at the Pennsylvania State College, Pa. The Institute proper lasts from July 4 to 30. Courses for college credit extend from June 25 to August 5. The Institute is a national affair, and students will be in attendance from all over the country. A section of new fraternity houses in one of the most attractive parts of State College has been taken over to house members of the Institute and lecturers. Some of these houses are reserved for women, and others for married couples.

The committee in charge, consisting of N. E. Gordon, B. S. Hopkins, C. E. K. Mees, C. M. A. Stine, G. L. Wendt, F. C. Whitmore, W. R. Whitney, and F. W. Willard, bas arranged a programme consisting of (1) A series of daily conferences; (2) Intensive courses of lectures carrying college credit; (3) Evening talks on popular science subjects; (4) Exhibits and educational films.

In addition to the educational phases of the Institute, the committee is arranging excursions, picnics, golf and tennis tournaments, and other recreational features, such as dancing and horseback riding.

CORRESPONDENCE.

A.S.L.I.B. DIRECTORY. 38, Bloomsbury Square,

London, W.C.1. June 23, 1927.

(To the Editor of the CHEMICAL NEWS.) Dear Sir,

May I be allowed through the medium of the Press to offer my thanks to all those who have kindly responded to my request for information in connection with the preparation of the Directory of Sources of (Specialised Information, and at the same time beg those who could assist but have not yet written to me to do so at once, as we are fast approaching the close of our work. I should especially like to be able to include some more collections in possession of private individuals. Yours faithfully,

the

G. F. BARWICK,

Secretary.

CUPRATES.

By ROBERT SAXON, B.Sc., F.C.S. (Member of the American Chemical Society). The author has suggested in the Chemical News that from the behaviour of copper pyrites under electrolysis the compound is the sulpho-cuprate of iron. Experiments on mixtures of chlorides, nitrates, or sulphates of iron and copper seem to point to the existence of a series of salts in which the positive iron ion throws over the copper to the negative side along with the anion. These mixtures in every case, whether the reagent is in defect or excess, give with sodium, potassium, or ammonium hydroxide a precipitate of composition corresponding to the formula FeCu(OH), where the ferric salt is used and FeCu(OH), with the ferrous. The latter salt is green like the ferrous salts, and the former brown. Excess of ammonia does not give any blue colouration, nor will ammonia dissolve any of the compounds on a filter paper, except after standing with them for hours, and then there is only a faint blue, no matter how much ammonia is used. It would seem that iron gives copper no chance as a positive ion, for very little iron (1.0 per cent.) will effectively prevent the formation of the blue compound, even when the iron should be satisfied. Under the circumstances it seems that the copper takes up the chlorine to form a compound anion as CuCl, or -CuCl, to form what may be termed chlorocuprites, and chloro-cuprates of iron. The double cyanides of copper are similar to these double chlorides, as in them there is no evidence of the existence of blue basic cuprion, but the iron manifests its usual green or brown basic ion, and not at all the red or yellow colours it assumes in the negative camp as ferrate, ferri-cyanide, or ferro-cyanide.

NEW ALBERTA GEOLOGICAL
REPORT.

The Scientific and Industrial Research Council of Alberta at Edmonton (Canada) has just issued its report No. 17 by Ralph L. Rutherford, entitled "Geology along the Bow River between Cochrane and Kananaskis, Alberta."

This report contains the results of a geological survey of a belt about ten miles. wide across the entire width of the foothills along Bow River.

The object of this survey was to determine the thickness and character of the various formations, and to work out the geological structure. This has been accomplished in a satisfactory manner by the author of this report.

a

aromatic organic compound such as phenol in the presence of a relatively insoluble substance adapted to act as a vehicle or diluent for the organo-mercury compound so formed. The diluent may be completely inert, or may react with the initial materials or with intermediate products formed in the synthesis of the organo-mercury compound, and may be of basic ,neutral, or acid character. Diluents specified are calcium or magnesium hydroxide or carbonate, aluminium oxide, barium carbonate or sulphate, clay, charcoal, infusorial earth, and calcium phosphate. The reactions specified in examples are those between hydrated lime, mercuric acetate and ortho-chloro-phenol, between mercuric acetate and ortho-nitrophenol sodium, between mercuric bichloride, sodium hydroxide and ortho-chlorophenol, and between mercuric acetate and betta-naphthol. In each case a water solution or suspension of the reagents, containing also an insoluble diluent, is heated to about 80° C. for several hours and the residue filtered off, dried, and powdered. The active material forms a surface layer on the particles of the diluent and not a mere mixture therewith.

The Latest TRADE MARKS

This list of Trade Marks of interest to Readers has been selected from the Official Trade Marks Journal, and is Published by permission of the Controller of His Majesty's Stationery Office.

BAUMATTE.

478,574.-All goods in Class 1 which includes acids, potash, salts and other chemical substances used in manufactures.-Montgomerie, Stobo and Company, Limited, Victory Works, George Street, Bridgetown, Glasgow. June 15th.

PURDEMAND. 479,390.-All goods in Class 1 which includes acids, potash, salts and other chemical substances used in manufactures. George Purdon & Co., 49, Commercial Road, London, E.1. June 15th.