The balance was made entirely of fused quartz, and consisted of a beam of the simplest possible construction, bearing at one end a small closed bulb and at the other a solid counterpoise. The whole was supported by a knife edge working on a polished quartz plate, and enclosed in a small case made of plates of glass in such a way that the pressure could be varied at will. The capacity of the whole "case" was about 2 cc., and the movement of the balance could be watched through a small telescope. It was sensitive to about one-millionth of a mgrm.

Mr. ROLLO APPLEYARD. Chain Apparatus for the Approximate Measurement of Logarithmic and Hyperbolic

Functions.

The apparatus consists of a chain suspended so as to form one half of a true catenary, and it is shown that by suitably proportioning the scale of measurement to the tensions of the chain the various quantities required can be obtained, to a first degree of approximation, by direct measurement from the suspended chain. These quantities include (1) the base of the Napierian logarithms; (2) the anti-logarithms of numbers to the Napierian base; (3) the hyperbolic function, Sin x, Cos x, Tan x, and Sec x. Special interest attaches to the apparatus, as it is just 300 years since the invention of logarithms by Baron John Napier, of Merchiston.

Prof. A. W. BICKERTON. The Polyscope.

A kaleidoscope rendered so optically perfect that a hundred reflections of a point or object may be seen. The angles of one are 30°, 60°, and 90°. Of the other, two angles 45° and one of 90°. They produce two classes of patterns, one suitable for textile fabrics, cretonnes, &c., the other suitable for floor cloths, tiles, &c.

Messrs. CHANCE BROTHERS AND CO., LTD., showed a number of specimens of Glass for Making Spectacle Lenses for the Absorption of Ultra-violet and Infra-red Rays and for the Reduction of Glare, based on experimental results given in Sir William Crookes's recent paper read before the Royal Society. Some of these glasses have the valuable property of almost completely absorbing the heat and ultra-violet radiations, and are useful for many purposes besides spectacles.

Exhibits were also given by the MARINE BIOLOGICAL ASSOCIATION, Profs. MACBRIDE, A. F. STANLEY KENT, E. B. PAULTON, the ASTRONOMER ROYAL, and many

others.

PHYSICAL SOCIETY.
Ordinary Meeting, May 8, 1914.

Dr. A. RUSSELL, Vice-President, in the Chair.

A PAPER entitled "Some Gyrostatic Devices for the Control of Moving Bodies" was read by Dr. J. G. GRAY.

The paper dealt with a number of new contrivances for stabilising, steering, and forcibly manoeuvring moving bodies, such as torpedoes and airships.

A number of old experiments were first shown. These included the "gyrostat on stilts" and "gyrostat on gimbals" experiments due to Lord Kelvin, the "crossed bifilar" experiment due to Prof. Blackburn, and a stilt top devised by Prof. Harold Wilson. It was shown that the gyrostatic system in each of these experiments, although exhibiting considerable balancing power, was not possessed of real stability. An unstable body rendered truly stable by gyrostatic action must possess the property that if displaced from the mean position it returns to, and comes to rest in, that position. The mean position is that in which the potential energy of the gyrostatic system is a maximum, and if the system is disturbed energy must be supplied to restore it to the mean, or undisturbed, position.

A number of new gyrostatic models were displayed in action. These include two-wheeled and four-wheeled gyro static motor cars and bicycles. These all provide examples

of gyrostatic systems provided with complete or real stability, and in all the cases shown the stabilising forces are derived from the propelling system.

One of the cars shown runs on two wheels in tandem, and is stabilised by a single gyrostat. This gyrostat is mounted in the car and controls the steering mechanism; it forms, in fact, a gyrostatic chauffeur. The model illusstrated a new form of torpedo and airship control. A second form of motor car, which also runs on two wheels in tandem, consists of two parts, a front one and an after one. The front part carries a gyrostat, the back part the propelling mechanism, and the two parts are connected together by means of a vertical hinge. The front part is propelled by the back part, and the arrangement is one of complete stability. The entire system may be manœuvred by means of the gyrostat. It was pointed out that by properly fitting an airship with a gyrostatic "nose" it should be possible to manoeuvre forcibly the airship by means of forces derived from the propellers.

The bicycles, which are provided with gyrostatic riders, are examples of moving bodies steered by gyrostatic action. The action is quite different from that of an ordinary bicycle. They are not "momentum" instruments. distance torpedoes, both submarine and aerial. The gyroThe devices shown are at once applicable to long

static system may be operated by the wireless transmission of electrical action.

At the conclusion of the paper the author showed a new series of animated gyrostats.

DISCUSSION.

Dr. W. WATSON thought the mechanisms shown were of great theoretical importance. He gathered, however, that the author himself thought they were more of theoretical than practical interest. He concluded some time ago that a two-wheeled car would not be of much use, as, although gyrostatic control worked satisfactorily either on a straight path or on a curved path of constant curvature, any attempt to alter the curvature had to be made with great caution. Hence a train built on this system would have to slow up on approaching either the beginning or the end of a bend. With a motor car, where one had to steer immediate courses on account of other traffic, the arrangement would be impracticable. At one time, when versely, makers of the latter type claimed that gyrostatic some cars had engines laid longitudinally and others transaction came into play and tended to prevent skidding. However, unless the gyrostat was free to move relatively to the car, one might as well have a lump of iron in its stead. He had investigated the amount of relative motion which might take place due to give in the springs or mountings, and it was quite insufficient to allow of appreciable gyrostatic action.

Mr. DUDDELL complimented the author on the collection of beautiful models which he had brought before the Society and the admirable way in which he had explained the principles underlying their action. He asked what speed was attained by the flywheels of the gyrostats.

Mr. R. S. WHIPPLE also expressed his admiration of the models.

Mr. F. J. WHIPPLE asked if the author had worked out the theory of the ordinary bicycle, and if it was his considered opinion that the rider had to perform the actions which he had described in steering. It was his opinion that when travelling rapidly this was not so, and that there was a stabilising effect due to the gryrostatic action of the front wheel. This was particularly noticeable in the way in which the wheel seemed to be pulled back into position if, when riding without the hands, the cyclist encountered a small stone.

Dr. RUSSELL asked concerning the use of the word "gyrostat." He remembered on one occasion when Lord Kelvin was showing some of these experiments to von Helmholtz an accident occurred which resulted in one of the gyroscope wheels passing through Helmholtz's silk hat. After that it was customary to enclose the gyroscope

in a brass case, and it was then usually called a gyrostat. He did not quite see why.

The AUTHOR, in reply, said that the larger gyrostats could be taken up to a speed of 20,000 revs. per min. in half-a-minute, and would run for 75 minutes. În steering a bicycle the rider turns the front wheel to the side to which the machine leans, and the forward momentum brings it up to the vertical position. The gyrostatic action helps, but only to a very slight extent. The name "gyro

stat

was the one invariably used at Glasgow since Lord

Kelvin's time.

A paper entitled" A Graphic Treatment of Cusped Wavefronts, and of the Rainbow," by Mr. W. R. BOWER, was taken as read in the absence of the author.

A method of drawing the cusped wave-fronts produced by refraction and reflection at a spherical surface and a graphic treatment of the elementary theory of the rainbow are described in the paper. The method is based upon the properties of the centre of juuction. In the case of reflection at a spherical surface in which aplanatic points are not available the position of the junction centre is obtained by elementary geometry.

By the use of junction-centres the distribution of the successive foci obtained on refraction and reflection at a spherical surface is readily plotted. If in the case of a rainbow it is assumed that the emergent portion of the effective pencil, as well as the incident portion, is one of parallel rays, then the distribution of foci with regard to the drop is a symmetrical one.

The caustics on refraction and reflection are also readily drawn as loci of points and envelopes of rays. Hence the wave-surfaces can be obtained. These in some regions are cusped, and the caustics are the loci of the

cusps.

In the case of pencils that are effective in producing rainbows, the lengths of the incident portion of the chiet ray intercepted by the spherical drop of radius, r, and a concentric sphere of radius, ru, are in the ratio I to n+1, where n is the number of internal reflections. This leads to a geometrical construction for finding the points of incidence of the chief rays of the effective pencils. These rays are at minimum deviation, and the same chief ray remains at minimum deviation, although the associated pencil may be converging or diverging.

SOCIETY OF CHEMICAL INDUSTRY. (LONDON SECTION).

Ordinary Meeting, May 4, 1914.

Prof. W. R. E. HODGKINSON in the Chair.

THE following papers were read and discussed :"A Reaction of Tetranitromethane." HODGKINSON.

By W. R. E.

The author describes a solvent action in certain metals, i.e., such as form amides or amino-like compounds, of an alcoholic ammoniacal solution of tetranitromethane. When the metal is placed in such a solution a yellow colour develops, the temperature rises, and there is a slight gas evolution (N2) (CO2). The action only becomes vigorous with copper after a small quantity of the blue cupramine compound has formed. When a cupramine solution is added to an alcoholic solution of tetranitromethane crystals form rapidly. They are identical with those formed from the metal. Similar results were obtained with nickel, zinc, cadmium - amine solutions, and with ammonium double salts of the metals. The salts appear to be of the general type C(NO2)3, NHM'3, NH3. They are nearly all deliquescent, and when rapidly heated explode.

"Application of Jets for Mixing." By Dr. OSCAR

NAGEL.

The low efficiency of jets is caused by the fact that about 75 per cent of the energy is consumed in the whirl which

is formed in the transit of the jet from one nozzle to another. This whirl effects the most intimate mixture of the motor-jet with the medium to be moved.

The use of jets as mixers is therefore suggested for various operations, such as the chamber process of manufacture of sulphuric acid. Preliminary experiments in this direction have been successful.

Apparatus for the Automatic Measuring and Injection of Chemicals." By the Hon. R. C. PARSONS, M.A., M.Inst.C.E. The author having referred to the crude methods gener ally adopted for introducing chemicals into water previous to its being filtered, proceeded to describe his low pressure injector, known by the name of the "Tiltometre," which is operated by means of the pressure obtained by inserting a venturi tube into the main in which the water to be treated flows. He then gave the results of the tests of this intrument, which proved to be an accurate and reliable apparatus for automatically treating water with a constant percentage of chemical, although the flow varies considerably.

He next explained his " High Pressure Chemical Injector," which also works by means of the pressure derived from a venturi tube inserted in a main.

This apparatus can inject against any pressure, and consists of two cylinders in which pistons having wide circumferential grooves move quite freely, and by means of a controlling valve are made to eject the chemical alternately, thus maintaining a regular flow. Above the cylinders are the inlet and outlet valves, the former for admitting the chemical from a tank in which it is stored, and the latter through which it is injected into the main. One one side of this instrument is a manometer for indicating the venturi pressure due to the flow through the main, and on the opposite another manometer attached to a small venturi tube through which the chemical ejected passes, and the amount discharged measured. The ratio of these discharges gives the percentage of chemical added, and can be adjusted by the regulating valve.

Both these instruments are shown to be simple, durable, reliable, and to yield very accurate results.

SOCIETY OF PUBLIC ANALYSTS AND OTHER
ANALYTICAL CHEMISTS.
Ordinary Meeting, May 6, 1914.

Mr. A. CHASTON CHAPMAN, President, in the Chair. MESSRS. Lauchlan Henry Dyke Acland, Walter Alan Gibbings, Frederic Herbert Lees, and William Henry Woodcock were elected Members of the Society.

Certificates were read for the first time in favour of Messrs. William Roscoe Hardwick, B.Sc., F.I.C., 13. Batavia Buildings, Hackins Hey, Liverpool; Harold Fletcher Hills, F C.S., Commercial Gas Works, Stepney, E.; Robert Hindle Kay, 72, Manor Road, Stoke Newington, N.

"Detection of Castor Seeds." By G. D. LANDER and J. J. GEAKE.

Á modification of the precipitin reaction as practised by Mooser and others, whereby direct extraction of a suspected material by means of physiological saline replaces the more costly and tedious method of extraction by glycerol.

"Composition of Milk and Milk Products." By H. DROOP RICHMOND.

As in previous years, the author gave a summary of the results of the analyses made in the Aylesbury Dairy Co., Ltd., during 1913; a sample of goat's milk and one of human milk was examined. It was shown that the aldehyde figure of cream calculated on the portion free from fat was the same as that of milk.

"Note on Sharps'." By J. F. LIVERSEEGE and G. D. ELSDON.

The permissible percentage of calcium sulphate in "sharps" (from grain) was discussed and a series of analyses of known samples was given.

"Action of Weak Acids on Soluble Fluorides." By P. A. ELLIS RICHARDS, F.I.C.

The author shows that the fluorides of the alkali metals are decomposed by many organic acids, including acetic, formic, tartaric, malic, lactic, benzoic, and salicylic acids, with liberation of hydrogen fluoride. Carbon dioxide gas passed through a solution of either sodium or potassium fluoride has a similar action.

"Simple Form of Fat Extractor." By G. A. STOKES. A simple fat extraction apparatus can be constructed by suspending a fat-free extracting thimble by means of wire in a long necked conical flask. The wire is fixed, and can be raised and lowered in the stopper, in which a condenser is fitted in the usual way.

INSTITUTE OF METALS. MAY LECTURE.

THE annual May lecture of the Institute of Metals was delivered by Prof. E. HEYN, of Berlin, in the evening of Tuesday, May 12th, at the Institution of Chemical Engineers, Engineer Vice-Admiral Sir HENRY J. ORAM, K.C.B., F.R.S., President of the Institute of Metals, being in the Chair.

Prof. HEYN said that it was a well-known fact that the welfare and convenience of modern mankind was, to a very considerable extent, influenced by the achievements of the engineer. People admired his work, and were daily confiding life and health to his creations. But only few were conscious of the fact that engineering work was, to a great amount, dependent on the possibility of manufacturing sound materials fit for the purpose and of keeping them sound in the course of the manifold processes that these materials required to go through until they were assembled into the admirable engineering structures presenting themselves to the public eye. Few persons were conscious of the enormous amount of thought bestowed on the question of soundness of materials by thousands of men fighting continuous struggles against the numerous hidden dangers involved in the intricacy of structural material and working strenuously towards its perfection and reliability.

Certain structural members might fail even without being subjected to stresses in service. For instance, it had often been observed that condenser tubes made out of brass cracked simply when stored up in the yard. Some articles made out of this metal, when exposed to atmospheric in uences, underwent an alteration to such an extent thatthey might be crumbled between the fingers. Similar phenomena could be stated in structural members made out of other metals and alloys, when they were manufactured under unfavourable conditions, which lead to serious internal strains.

The author said that he had made a special study of the phenomena connected with internal strains, investigating their causes and devising a method for measuring their amount. In his lecture the author dealt specially with the internal strains produced by cold working of metals (cold drawing, cold rolling, cold hammering, &c.). He showed that by these operations under unfavourable conditions internal strains might be set up in structural members which came close to their resisting power, so that even trifling additional strains caused by external forces or other circumstances (scratching of the surface, unequal heating or cooling, slight corrosion by certain agents, which were contained in the atmosphere or by certain paints) might lead to unforeseen fracture. He discussed the means for removing or diminishing such dangerous internal strains, and illustrated his lecture by numerous samples taken from the domain of practical engineering.

NOTICES OF BOOKS.

The Synthetic Use of Metals in Organic Chemistry. By ARTHUR J. HALE, B.Sc. (Lond.), A.I.C. London: J. and A. Churchill. 1914.

FOR advanced students of organic chemistry this will be found a very useful handbook. The different types of reactions effected by the metals and their salts are described, with references to the original papers relating to them, and full directions are given for practical work illustrating some of the more important reactions. The student who has a fair general knowledge of the operations of practical chemistry will be quite well able to carry out the experiments without any help from a demonstrator, for the directions are very explicit, and quantities employed and yields to be expected are always stated. For the chapters on practical work, which form perhaps the most useful part of the book, the information has been collected from many foreign periodicals, and it will be a boon to students who do not read German and French easily, or to those who cannot readily get access to the Berichte, &c.

A Third Year Course of Organic Chemistry. By T. p. HILDITCH, D.Sc.(Lond.), F.I.C. London: Methuen and Co., Ltd. 1914.

THIS book is the sequel to Dr. Dunstan's "First Year Organic Chemistry " and Mr. F. P. Thole's "Second Year Organic Chemistry," and deals with the heterocyclic compounds, and also with some of the more complex aliphatic and carbocyclic compounds not discussed in the earlier books. These include the sugars, polypeptides, and terpenes. The book will be found a useful and safe guide for candidates for such examinations as the Honours B.Sc. degree of London University. The author has introduced many valuable summaries and schemes showing constitutions, which are likely to impress themselves on the student's memory, and he has been judicious in selecting his material well, and not overburdening the text with details. It is a pity that small print has been used so much, for the type in which some of the formulæ are printed renders them almost undecipherable.

Knapp. 1914. (Mk. 13.60). the binary compounds of carbon and silicon with other THIS monograph treats from a scientific point of view of elements, and gives a very complete account of the subject. Technical processes and patents are not, as a rule, included for discussion, but all laboratory work on carbides and silicides is very fully described. The early sections deal with the preparation and properties of carbides in general, and then each individual compound is described in full. The silicides are treated similarly, and the monograph Flaschner on the thermic analysis of silicides and carbides. concludes with an appendix contributed by Dr. Otto

Contribrición al Estudio de la Imagen Latente Fotografica. ("Contribution to the Study of the Photographic Latent Image"). By LUIS GUGLIALMELLI. San Martin : Imprenta de "El Nacional." 1913.

THIS volume contains a thesis presented to the University of Buenos Aires by the author for his doctorate. It gives a critical summary of the various hypotheses concerning the latent image which have been put forward, grouping them as physical, chemical, and physico-chemical. The last class, and in particular the colloidal theory, is considered in the greatest detail, the author believing that the bulk of the evidence that has been accumulated is in its favour.

THE CHEMICAL NEWS

VOL. CIX., No. 2844.

of water in this tube regulates the pressure of gas given by the apparatus.

The air pressure forces acid through the wide tube (4) on to the sulphide (6), a layer of coarsely broken glass (5) acting as a rough filter. The gas is washed (7) and delivered at the tap (9) or stored in the vessels (8), from which the solution may be taken. A tap between 6 and 7

By FREDERIC WILLIAM RIXON.

THE apparatus described below has undergone a severe test for six months; during that time it has worked most satisfactorily. It possesses certain advantages which will

Renewal of acid follows by means of funnel (3) and tap (4). The whole apparatus may be readily fitted up from stock material, and admits of considerable variation to meet different requirements; for large laboratories it can be made to act automatically and deliver gas at a constant pressure, while if occasional supply only is required the apparatus will stand idle without losing efficiency.

be equally appreciated in laboratories where sulphuretted hydrogen is used constantly or even very intermittently. Some of these advantages may be mentioned.

A larger charge of iron sulphide may be used; the spent acid is easily replaced; when the apparatus is not in use the acid cannot possibly come into contact with the sulphide; the acid is totally enclosed; there is a reservoir of gas; gas and solution can be obtained, and the arrangement is practically fool proof.

Description of Apparatus.

Air pressure is obtained by using a filter pump (1) as a blower; too great pressure is relieved by the safety tube (2), which is of wide tubing sealed with water; the height

The only replacement entailing a partial taking down o the apparatus is the refilling with sulphide. University of Bristol, April 30, 1914.

Potassium Trioxide and the Stability of Alkaline Peroxides.-R. de Forcrand.-The heat of formation, starting from the elements, of the four alkaline trioxides, Na2O3, K203, Rb2O3, Cs2O3, is practically the same, viz., +126 cal. The passage from the monoxide to the dioxide disengages quantities of heat which regularly increase from calcium to cæsium:-Ca, 4'11; Li2, 7'97; Sr, 13'07; Ba, 18:36; Ra, 187; Na2, 19'03; K2, 220; Rb2, 24'1; CS2, 250.-Comptes Rendus, clviii., No. 14