Jan. 29, 1885] 



NA TURE 



305 



of magnetising force, and also to subsequent cyclic changes of 

 magnetising force, such as complete or partial removal and re- 

 application, or reversal. The curves are drawn by plotting either 

 ft, the intensity of magnetisation, or 33, the magnetic induction, 

 ii to ?!>. the magnetising force : the characteristics of 

 these curves and their relation to the physical state of the piece 

 under examination are pointed out. Curves so drawn invariably 

 exhibit the static lagging action to which the author (in a former 

 paper) gave the name "hysteresis," any cyclic change of Jt| 

 giving rise to a more or less nearly closed loop in the curve. 

 Attention was previously drawn to these loops by Warburg, who 

 also anticipated the author in pointing out their important 

 physical meaning, namely, that the area of a loop, or -_/"ftVfl}, 

 i^ure of the energy expended in performing the cycle 

 of magnetisation which the loop describes. In the present paper 

 absolute measurements of this energy are given, espe- 

 cially of the energy which is thus dissipated in each reversal of 

 ill magnetism of a piece of iron or steel. These show that 

 while the dissipation of energy by reversal of magnetism is very 

 much smaller in soft iron than in hard iron or steel, even in the 

 latter its amount is very trilling, so that the principal part of the 

 heal which is produced in the cores of electro-magnets must be 

 due chiefly to other causes than this static hysteresis, and i-, in 

 fact, due almost wholly to the induction of so-called Foucault 

 currents in the cores. The relation of this hysteresis to Weber's 

 theory of molecular magnets, as extended by Maxwell, is dis- 

 cussed, and the insufficiency of Maxwell's extension noticed. 



By vibrating a piece of soft iron during the application and 

 removal of magnetising force, the effects of hysteresis are almost 

 entirely removed, and the iron is then found to possess almost 

 no retentiveness. But when the application and removal of 

 magnetising force are effected without mechanical disturbance, 

 the retentiveness of soft iron is found to be even greater than 

 that of steel. In some cases 93 per cent, of the whole induced 

 magnetism of a piece of annealed iron was found to remain on 

 the complete removal of the magnetising force. It is pointed 

 out that there is no discrepancy between this result and the well- 

 known fact that a short iron core of an electro-magnet retains 

 almost no magnetism when the current in the magnet is inter- 

 rupted. In that case the ends of the magnet itself, after the 

 interruption of the current, exert a sufficient reversed magnetising 

 force to destroy almost entirely the residual magnetism. But 

 ted under the conditions which give uniform magnetisa- 

 tion and avoid the demagnetising influence of the ends, soft 

 annealed iron is more retentive than even the hardest steel. 



Examples are given showing that the influence of permanent 

 set in the curve of magnetisation is so marked as to give a crite- 

 rion by which a strained piece may be readily distinguished from 

 an annealed piece of metal, and that strain diminishes very 

 greatly the magnetic retentiveness of iron. 



Numerical values of the coefficients of permeability (p) and 

 ptibility (k) are given for a number of samples of iron 

 and steel, and the relation of these coefficients to 33 and £ is 

 exhibited graphically after the manner of Rowland. The greatest 

 value of n refers to soft annealed iron while under mechanical 

 vibration, and is about 20,000. 



The next part of the paper deals at great length with the 

 effects of stress (consisting of longitudinal pull) on the magnetic 

 susceptibility and retentiveness of iron ; and the last part deals 

 more briefly with the effect of temperature on magnetism, a 

 subject already largely treated by G. Wiedemann and others. 



The experiments, which have been of a very extended charac- 

 ter, were made during 1SS1-S3 in the laboratory of the Univer- 

 sity of Tokio, Japan, with the help of Japanese students, 

 Messrs. Fujisawa, Tanakadate, Tanaka, and Sakai, to whom 

 the author is indebted for much valuable assistance. The results 

 • i. almost without exception, reduced to absolute mea- 

 sure, and are for the most part presented graphically in curves 

 which accompany the paper. 



January 22. — " On the Origin of the Proteids of the Chyle 

 and the Transference of Food Materials from the Intestine into 

 the Lacteals." By E. A. Schafer, F.R.S. 



The mosl important result obtained by the author is the esta- 

 blishment of the fact that, during absorption of food from the 

 the lymph corpuscles migrate in large numbers into 

 the lacteals, and for the most part become disintegrated and 

 dissolved in the chyle. This is the case not only after a meal 

 containing fat, but also after feeding with substances devoid of 

 that alimentary principle ; it is, therefore, a phenomenon of 

 general occurrence during absorption, and the carrying of fatty 



particles into the lacteals after a meal containing fat by the 

 immigrating leucocytes, must be regarded as merely incidental 

 to a more general function. 



The immigration and solution of numerous leucocytes in the 

 contents of the lacteals must be the means of conveying a large 

 amount of proteid material, derived from their dissolved proto- 

 plasm and nuclei, into the chyle. And any other material which 

 may be mechanically or otherwise incorporated with their proto- 

 plasm must also be set free. In this way the fatty particles 

 which they contain during absorption of a meal containing fat 

 become released and suspended in the chyle, and it is probable 

 that amyloid matters are also in part thus conveyed to that fluid. 



A fuller account of the whole subject, furnished with illustra- 

 tions and containing the necessary references to other articles 

 dealing with the same question, will appear in the forthcoming 

 number of the Monthly International Journal of Anatomy and 

 Histology. J J J 



Geological Society, January 14.— Prof. T. G. Bonney, 

 F. R.S., President, in the chair. — Ewan Cameron Galton, 

 Henry Brougham Guppy, Henry G. Hanks, and William 

 Elliott Howe were elected Fellows of the Society. — The fol- 

 lowing communications were read : — The melamorphism of 

 dolerite into hornblende schist, by J. J. Harris Teall, F.G.S. — 

 Sketch of the geology of New Zealand, by Capt. F. W. Hutton. 

 F.G.S. , Professor of Biology in the Canterbury College, Uni- 

 versity of New Zealand. The paper commenced with some 

 general remarks on the importance and variety of the geology of 

 New Zealand, and on the progress made in the investigation of 

 the islands. The author then proceeded to the question of the 

 classification of the sedimentary strata, which the author 

 arranges in the following local systems : — 



Systems Probable age 



Recent Recent 



Pleistocene Pleistocene 



Wanganui Newer and Older Pliocene 



Pareora Miocene 



Damaru Oligocene 



Waipara Upper Cretaceous 



Hokanui Lower Jurassic and Triassic 



Maitai Carboniferous 



Takaka Silurian and Ordovician 



Manapouri Archaean 



Most of these systems are divided into several local series. The 

 general geological structure was then treated. The south island 

 of New Zealand was shown to be traversed from near the 

 southern extremity to Tasman's Bay by a curved anticlinal, con- 

 vex to the westward ; and the strata to the east of this axis are 

 thrown into secondary folds, which mainly affect the beds older 

 than Tertiary. A great north and south fault occurs west of the 

 anticlinal. The north island is very different. It is traversed 

 by a narrow ridge, the country northward of which is broken by 

 three great volcanic cones, Mount Egmont, Ruapehu, and Ton- 

 gariro near the centre of the island. The oldest rocks seen 

 south of Cook's Straits are not repeated to the north, and a fault 

 may traver.-e the Straits. The rock systems up to the Hokanui, 

 inclusive, are similar in lithological character throughout New 

 Zealand, and appear to have been formed on the shore of a 

 continent with large rivers. The higher systems, with the ex- 

 ception of a few coral-reef limestones, are locally variable, and 

 may be considered insular. The relative distribution of sedi- 

 mentary and eruptive rocks was briefly noticed, and the occur- 

 rence of some useful minerals mentioned. No workable coal is 

 found below the base of the Waipara system. A description of 

 the different systems and of the series into which they are 

 divided followed, commencing with the oldest. The distribu- 

 tion, lithology, and thickness of each system were noticed briefly, 

 and lists of the most important fossils were added. The eruptive 

 rocks associated with each system were next noticed in the same 

 order, and the paper concluded with notes on the distribution of 

 volcanic rocks in the north island, on hot springs, and on the 

 minerals found in New Zealand. — The drift deposits of Colwyn 

 Bay, by T. Mellard Reade, F.G.S. 



Zoological Society, January 20. — Prof. W. H. Flower, 

 F.R.S. , President, in the chair. — Mr. Sclater called attention to 

 the breeding of a pair of the Chinese Blue Magpie in the 

 Society's Gardens in 1SS4, and exhibited specimens of their eggs. 

 — Prof. Bell exhibited some models illustrating the paper of 

 Rathke on the development of the great blood-vessels in the 



