When mechanical vibrations or electric oscillations are superposed at all points of a normal hysteresis loop, the induction at the cyclic extremes is increased, the residual magnetisation decreased, and those differences of magnetic condition to which hysteresis gives rise lessened. The curves delineating these changes form a continuous loop, and neutral points occur where vibrations superposed upon decreasing cyclic field produce no induction change whatever.

The initial irreversible effects of applying or of removing stress resemble those produced by vibrations, although these processes “may be conducted in such a way that no actual vibration takes place.” Ewing has investigated the initial effects of tension in iron, Cree the initial effects of pressure in cobalt. In iron and cobalt, tension and pressure respectively increase the induction before the Villari reversal in both metals is reached. Vibrations also in non-cyclic fields increase induction. Consequently in low fields the initial irreversible and final reversible effects of tension and pressure in iron and cobalt respectively augment each other. In nickel, on the other hand, the irreversible and reversible effects of tension must oppose each other; the latter effect lowering the induction at all stages of field increasing from zero. In Ewing and Cowan's paper, however, no mention is made of any initial effects tending towards induction increase.

The object of the experiments described in this paper was to study the cooling of nickel, and to endeavour to get recorded any recalescence which might occur. A specimen of pure nickel could not be obtained, but the nickel worked with, supplied by Messrs Johnston & Sons, contained less than 2 per cent, of impurities.

In the third volume of his Spectroscopie, p. 91, Kayser has raised the question whether on mixing two coloured solutions which do not act on one another chemically the absorption spectrum of each of the components remains unchanged. Melde thought he had discovered such an effect; he stated that when a solution of carmine in ammonia which has two sharp bands in the green, was added to a solution of potassium dichromate which absorbs the violet end of the spectrum, or to an ammoniacal solution of copper sulphate which absorbs the red end, that the carmine bands were in each case displaced towards the end absorption in question. He ascribed this to a physical action between the molecules. It was, however, pointed out by Schuster that a shift of this nature would be seen if, instead of mixing, the one solution was merely placed behind the other. Bostwick and Krüss repeated Melde's work, and came to the conclusion that there was a real shift in addition to the apparent shift pointed out by Schuster. Since then additional evidence has been adduced by Formánek and has been quoted by Kayser in the section cited above. The object of the research recorded in this paper was to investigate those cases with the most accurate means possible, and, if a shift was established, to decide if it was physical.

It has been mentioned by Professor Voigt of Göttingen in his newly published book and by Professor Zeeman of Amsterdam in the Physikalische Zeitschrift, that I have found examples of strongly marked dissymmetry in studying the Zeeman Effect in tungsten and molybdenum. Professor Zeeman has also discovered and published such cases of dissymmetry in other elements. Not only have many examples of normal dissymmetry been found, but almost as many cases of abnormal dissymmetry. To explain those terms, normal and abnormal, let us consider that the single spectrum line is broken up, when the light is in the magnetic field, into the three components, 1, 2, 3, where the numbers begin from the component which has the shortest wave-length. In the normal dissymmetrical triplet the middle component is nearer the component on the red side than that on the violet one, i.e. for the normal type the interval 1–2 is greater than the interval 2–3, but in the abnormal dissymmetrical triplet 2 is nearer to 1 than to 3. These observations of Professor Zeeman and myself, which were made at the same time in the Universities of Amsterdam and Göttingen, having been communicated to Professor Voigt, he wrote and published in the above-mentioned book an extension to his and Professor H. A. Lorentz's theories of the Zeeman Effect. In his original theory Professor Voigt had shown that, considering the electrons as uncoupled, cases of normal dissymmetry might arise among the Zeeman triplets, this dissymmetry being accompanied by a greater intensity of the red component than the violet one. He pointed out also that the ‘absolute’ dissymmetry or the difference between the absolute displacements of the red and violet components should be independent of the magnetic field strength used to produce the Zeeman Effect. To explain the large numbers of complicated types of Zeeman Effect which have been found —in the study of the Zeeman Effect in tungsten I discovered lines with no fewer than 17 to 19 components, the largest numbers hitherto found—Professors Voigt and Lorentz made use in their theories of couplings between electrons of the same vibration frequencies.

This research was commenced with a view to find the velocity at which arsenic was liberated as arseniuretted hydrogen from cathodes of different elements:

(a) From arsenic in the form of arsenious acid.

(b) „ „ „ „ arsenic acid.

In the course of his researches on mucic acid, Professor Crum Brown found that this acid could not readily be nitrated in the ordinary way.

During the first seven months of the year 1908 I had the good fortune to be living at Invergarry in Inverness-shire, with sufficient time at my disposal to make temperature observations in Loch Garry, and, through the generosity of Sir John Murray and Mr Laurence Pullar, the funds of the Lake Survey (Pullar Trust) were put at my disposal to defray the expenses of observation. I was further fortunate in securing the services of Mr Wm. Macdonald, Mount Pleasant, Fort Augustus, who was previously boatman to the Lake Survey on Loch Ness, and who proved himself a most painstaking and eager observer, and by whom by far the greater number of the actual observations were made.

§ 1. In the case of a function of two variables f(x, y) there is, in general, no connection between the results of proceeding to the various limits, upper, lower, and intermediate, first with respect to x and then with respect to y, and first with respect to y and then with respect to x. We cannot even assert that the repeated upper limit obtained in one way is not less than the repeated lower limit obtained in the other way.

The following experiments originated in a series of laboratory exercises which I performed on the use of the Dolezalek electrometer. The instrument which I used was made by Bartels, and had its needle suspended by a phosphor-bronze strip. This needle was raised to a potential of about 160 volts by being connected to one terminal of a battery of eighty small secondary cells, the other terminal of which was connected to earth. When at this potential the instrument gave, for a potential difference of 1 volt between its two pairs of quadrants, a deflection of 200 divisions on a scale 200 centimetres distant from it. The maximum deflection in the experiments described was 166 divisions, i.e. 33·2 cms., giving tan−1 ·166 as maximum angle of deflection; and therefore, by taking the deflection as proportional to the potential difference, a maximum error of 0·7 per cent, is introduced.

Some years ago, when employed in work that involved the use of a polarimeter. there was brought forcibly to my notice the great loss of time which the frequent reading of the Nicol dial necessitates. To avoid this, I had a special form of camera made for the purpose of recording the readings automatically. This method proved successful from the first, but it is only lately that the mechanism of the camera attained its final form; for it has required several years of experiment and alteration to evolve a form of camera which should be wholly automatic and yet reasonably simple. It will be readily understood that the function of the camera is to make a series of photographs of the scale-and-vernier of the polarimeter or other instrument, which, on subsequent examination, will show the relative position of the scale-and-vernier at the time of each exposure.

In the usual form of magnetometer the magnetising solenoid is placed with its axis in the magnetic east and west line passing through the magnetometer needle. The effect of the current is balanced at the needle by means of a compensating coil connected up in the circuit. This latter coil has its axis coincident, or nearly so, with that of the solenoid. When a feebly magnetic specimen is under examination the solenoid, and consequently the compensating coil, must of necessity be brought up close to the needle. If large magnetising currents are employed, any small shift of the coils from their correct positions may be sufficient to seriously impair the balance. In consequence of this the operation of adjusting the position of the compensating coil (the solenoid is usually clamped once for all in a convenient position) is a difficult one, especially as the slight inevitable movement of the coil which results from clamping it in position generally results in the balance being interfered with.

Archibald Scott Couper is one of the most singular appearances in the history of the development of Organic Chemistry in the nineteenth century. He comes on the scene at the time—the end of the ‘fifties—when the valency theory began its victorious entrance into our science.

In May 1907 a paper was read before this Society by one of us on the magnetic properties of the Heusler alloy. After that date the investigation was extended to two other copper-manganese-aluminium alloys, and latterly the scope of the research has been further extended by a series of tests carried out by the present authors conjointly on simple aluminium and manganese bronzes, and on the constituent metallic elements in the pure form, while additional tests have been made on the manganese-aluminium bronze. Some of the more interesting results obtained since the 1907 paper are given in the present communication.

The alterations brought about in the magnetic moments of magnets, composed of various metals and alloys, by alternate cooling and warming between ordinary room temperature and that of liquid air have been very fully investigated by Dewar and Fleming. It was found by these experimenters that in the case of most of the metals examined the effect of the first cooling upon the magnet—which had previously been magnetised to saturation in the field of an electromagnet—was to bring about a very considerable reduction in its magnetic moment. On allowing the magnet to warm to room temperature its magnetic moment still further diminished. On cooling once more to the liquid air temperature the magnetic moment increased, and from and after this stage it was found that the magnetic moment of the magnet when cold exceeded that of the magnet when at room temperature by a definite amount. The changes brought about by the treatment were found to be much greater in the annealed than in the quenched condition of the material.

The discharge of water through a vertical circular orifice is represented by an expression which does not admit of a direct mathematical solution, but from which results have been obtained by graphical means. The shape of the curve of actual discharge is similar to that found for the theoretical discharge; both curves are sensibly straight lines for positions of the water surface between the centre and the top of the orifice. The value of the coefficient of discharge probably lies between 0·625 and 0·630 for low heads.

This investigation was undertaken with the view of determining the number of free iodine ions present in saturated solutions of iodine in potassium iodide of varying strengths.

L'existence des Macruridæ à l'intérieur du Cercle Polaire Arctique est connue depuis longtemps.

C'est Sven Lovén qui en rapporta le premier exemplaire (Macrurus berglax), de Hammerfest (Finmark), lors de la première Expédition suédoise au Spitzberg, sur l'Enigheten, en 1837.

It is now well known that Lagrange's equations of motion for a system of connected particles are not applicable to certain cases of motion—for example, to a rigid sphere rolling without sliding on a given surface. In his Principien der Mechanik, Hertz has referred at considerable length to this subject, and has applied the adjective “holonomous “to those systems to which the equations are applicable, and has called all others “non-holonomous.” These adjectives correspond to distinct characteristics of the systems as regards the constraints to which they are subject. Holonomous systems are those in which the constraints are expressed, or can be expressed, by finite equations; in non-holonomous systems, on the other hand, these conditions, or some of them at least, are expressed by differential relations, which do not fulfil the conditions of integrability.

In the volume of the Arch. Néerlandaises for 1900, Dr Bryan discussed the investigation of the distribution of the velocities of a dynamical system for a stationary state from probability considerations.

He suggested the method of obtaining expressions for the second differential coefficients with respect to the time of squares and products of velocities such as enter into the expression for the kinetic energy, and finding from them equations of energy equilibrium, as well as conditions of stability for the stationary state.

He applied the method to a few simple examples, and indicated in these the preponderance of conditions for non-equipartition of energy.