PHYSICS, PROGRESS OF, IN 1902. 



PHYSIOLOGY. 



557 



-to secure such stability is greatest for iron and 

 least for tempered steel. It is practically inde- 

 pendent of the magnetizing force, being about 65 

 per cent, in iron, where it does not depend on the 

 form of the iron. With steel it varies from 7 to 

 about 20 with the form of the metal; with 

 tempered steel it varies from about 0.2 to about 

 0.9 per cent. In tempered steel, even though 

 the magnetization be not uniform, it is possi- 

 ble to attain approximately perfect stability 

 in all points of the metal. Klemencic (Annalen 

 der Physik, August, 1901) observed the moments 

 of three permanent magnets over a period of about 

 five months, the magnets being kept in iron cases 

 lined with cotton to protect the magnets from 

 shocks. During the first few days the magnets 

 showed a small change (less than 1 per cent.), 

 but after this the moment of each magnet re- 

 mained constant within the limits of error of the 

 experiments. These changes the author attributes 

 to magnetization or demagnetization of the case. 

 The experiments show that there is a great advan- 

 tage in keeping magnets in iron cases. 



Magnetostriction. C. Barus (Physical Review, 

 November, 1901) asserts that accepted theories of 

 magnetostriction are faulty in ignoring viscosity. 

 From Kelvin's work we know that mechanical 

 strain is accompanied in solids by viscosity and 

 slip between the particles. But magnetization 

 produces strain; hence we should expect the 

 phenomena of magnetostriction to involve viscos- 

 ity and slip. To test the matter Barus subjects 

 a soft iron wire to a fixed torque, corresponding 

 to a definite deflection on a scale. If the wire be 

 magnetized the deflection changes, and when the 

 field is removed the final deflection is found to 

 differ from the original one. The author finds by 

 investigation (1) that in the presence of an im- 

 pressed strain a longitudinal field produces in- 

 creased rigidity and temporary set; (2) tempo- 

 rary and permanent set occur in twisting, just 

 as in magnetization. H. Nagaoka and K". Honda 

 (Comptes Rendus, March 3) have experimented 

 with nickel-steels having respectively 25 per cent., 

 29 per cent., 36 per cent., and 46 per cent, of nickel. 

 The first was not sensibly magnetic, and showed 

 no change of length on magnetization ; the second 

 was sensibly magnetic, and varied in length slow- 

 ly with the field; the third was strongly magnetic, 

 and varied at first rapidly, but soon approached a 

 limit. The fourth was intermediate between the 

 second and third in properties. The variation in 

 volume becomes less as the alloys are more strong 

 in x nickel. Thermal changes influence these obser- 

 vations very little. Thus, although the third alloy 

 has a coefficient of themial expansion about one- 

 tenth as much as the second and fourth, its varia- 

 tions in dimensions are intermediate between 

 those of the other alloys. 



Magneto-optics. P. Zeeman (Royal Amster- 

 dam Academy, May 31) notes that instead of a 

 negative rotation in the interior of an absorption 

 band, as required by Voigt's theory, Corbino has 

 obtained a small positive rotation only. He has 

 therefore tested the question by observing the al- 

 terations shown by the interference bands of a 

 Fresnel prism system in the neighborhood of the 

 sodium lines, the amount of sodium vapor in the 

 magnetic field being gradually increased, while 

 the field is kept constant. In a field of 18,000 

 units, a displacement corresponding to a negative 

 rotation of approximately 400 was observed in 

 the case of both lines, increasing the magnetic 

 field will produce a diminution of this negative 

 rotation. For very high vapor densities, how- 

 ever, phenomena identical with those recorded 

 by Corbino were noted. Further experimental 



work appears to be necessary to account for the 

 phenomena observed. C. Runge and F. Paschen 

 (Sitzungsberichte of the Berlin Academy", April 10) 

 have verified for five different metals Preston's 

 observation that lines of elements corresponding 

 according to the series laws, are so decomposed 

 in the magnetic field that on a scale of vibration 

 numbers the components of corresponding lines in 

 equal magnetic fields stand at equal distances. 

 When the lines are normal triplets it follows, from 

 H. A. Lorentz's laws, that in the spectra of the 

 different elements the relation of the charge to the 

 mass of each particle is the same; and so the dif- 

 ferent spectra appear to be due to identical parti- 

 cles with an intermolecular material correspond- 

 ing to the respective elements. Possibly similar 

 charged particles oscillate round their centers 

 of gravity while the chemical molecules determine 

 the forces with which the particles are, in the ab- 

 sence of a magnetic field, drawn into equilibrium. 

 This would make the spectrum different for each 

 element; while the decomposition of correspond- 

 ing lines in a magnetic field would be equal in 

 different spectra. 



PHYSIOLOGY. General and Theoretical. 

 In an address on The Relation of Biology to 

 Medicine, Prof. J. Rose Bradford, of University 

 College, London, adduced a few instances to show 

 how a knowledge of biology contributes to giving 

 our knowledge of the facts of human physiology 

 a wider grasp. Looking at the function of res- 

 piration from the point of view of the human 

 organism, we would necessarily conclude " that 

 lungs are necessary, that muscles are necessary, 

 that blood-corpuscles are necessary, that hemo- 

 globin is necessary, and that therefore iron is 

 necessary. If you look at this function from the 

 point of view of biology, or of comparative anat- 

 omy, you will be able to find illustrations in the 

 animal kingdom in which each of these several 

 structures that I have mentioned may be absent. 

 There are large groups of organisms without 

 lungs, but having branchiae; there are organisms 

 with lungs, but with no diaphragm or an incom- 

 plete diaphragm; there are animals which breathe 

 with their skin; there are animals which have 

 hemoglobin dissolved in the blood plasma instead 

 of the corpuscles; and there are animals which 

 have no hemoglobin, as, for instance, in the crus- 

 tacea, where the iron-containing hemoglobin is 

 often replaced by a copper compound. Facts 

 such as these, which, as I say, can be acquired 

 without any great labor, and which are of no 

 distinct practical utility, are at the same time 

 of immense importance to a properly educated 

 medical man from the point of view of enlarging 

 his conception of physiological processes in gen- 

 eral. There are similar illustrations to those ad- 

 duced as regards respiration to be adduced as re- 

 gards circulation, but I will not take up your 

 time by going into that, and I will not delay you 

 with the very large question which is of great 

 interest to the physiologist and to the zoologist 

 as to whether many of the micro-organisms in 

 the alimentary canal are not really instances of 

 complicated symbiosis, of which one has so many 

 illustrations both in the vegetable and the animal 

 kingdom. It is a vexed question which this is 

 not the place to enter into. I simply mention 

 it as an illustration of the wider grasp afforded 

 by an intelligent study of biology." 



Prof. W. C. Halliburton, in his physiological 

 address at the meeting of the British Association, 

 said that the revival of the vitalistic conception 

 in physiological work appeared to him a retro- 

 grade step. To explain anything we are not fully 

 able to understand in the light of physics and 



