504 



NA TURE 



[October 21, looq 



WORK OF THE PHYSIKALISCH- 

 TECHNISCHE REICHSANSTALT IN 190S. 



T7ROM the annual report of the above institution for 

 last year, recently published, we find that the same 

 steady progress is made in research worlv of a varied 

 nature ; the following notes give some particulars of a 

 few of the more interesting investigations completed or in 

 progress in 1908. 



The saturation pressure of water vapour between 50° 

 and 200° was determined as a continuation of the experi- 

 ments in the previous year, the resultant pressures being 

 tabulated in the report. The limit of accuracy over the 

 whole range depended on the measurement of tempera- 

 ture, and the greater part of the work was devoted to such 

 measurements. In the neighbourhood of 100° the tempera- 

 ture scale could be considered as trustworthy to o-oi°, and 

 at 200° to 0-02°. The platinum thermometers used were 

 compared at 150° and 200° with the nitrogen thermometer, 

 after the constants of the latter had been determined, the 

 comparison being made in an electrically heated oil-bath. 



The experiments on the heat of evaporation of water, 

 which were previously made between 30° C. and 100° C, 

 have been continued for temperatures above 100°. Up to 

 the present it had only been possible to obtain the values 

 for the evaporation-heat from Regnault's observations of 

 the total heat by calculating the heat of the water. It 

 therefore appeared desirable to make direct measurements 

 of the evaporation-heat. The experiments were carried out 

 between 100° C. and 180° C. The results show that in 

 the first approximation it is admissible to extrapolate 

 beyond 100° the formula 



L = 94.2.o(36s-tr"'='Cal. 15. 



which has been drawn up for the evaporation-heat L 

 between 30° C. and 100° C. as limits for t. 



The work connected with the silver voltameter was 

 brought to a conclusion, and a paper published dealing 

 with the subject. The object of the measurements was 

 (i) to compare with the aid of the voltameter and a 

 resistance the E.M.F. of the Weston normal cell, which 

 was last determined by means of the silver voltameter in 

 189S ; (2) to determine the accuracy attainable in measure- 

 ments with the silver voltameter (a) under conditions which 

 are as regular as possible, and (fc) with a variation of the 

 factors in connection therewith. It was found (as at the 

 National Physical Laboratory) that the differences obtained 

 by Richards and by Schuster, attributable on the one hand 

 to the influence of the anode liquid, and on the other to 

 that of the oxygen, could not, within the errors of observa- 

 tion, be confirmed. 



Particulars of the changes in shellacked manganin coils 

 due to varying humidity were published in 1908. The 

 changes in question are' so slight in the German climate 

 as only to be of importance for resistances equal to or 

 greater than 100 ohms, and even then only for measure- 

 ments of the highest precision. For resistance standards 

 of 1000 and 10,000 ohms the changes during the summer 

 of iqo8 amounted to 5 parts in 100,000 only. By taking 

 the precaution of keeping resistances in a hvgrostat of 

 50 per cent, humidity the constancy of all resistances up 

 to a ioo,ooo-ohm coil was secured. A comparison of the 

 mercury standards with the manganin coils is in hand. 



Various institutions (e.g. the National Physical Labora- 

 tory, Teddington, and the Bureau of Standards, Wash- 

 ington) have issued specifications for the setting up of 

 standard cells, and detailed instructions are given for the 

 preparation of the mercurous sulphate. It is directed that 

 this salt shall not be washed with water, but with dilute 

 sulphuric acid or with a saturated solution of cadmium 

 sulphate._ The Reichsanstalt is of opinion that the manner 

 of washing the preparation is without influence on the 

 result. It follows from this that the same E.M.F. results 

 whether the salt be hydrolysed or not. 



_ In connection with the research on anode rays men- 

 tioned in the last report, it was found that when in the 

 presence of substances which emit intense anode ravs the 

 electro-negative bodies such as iodine, bromine, &c.', con- 

 siderably favour the formation of the ravs. It was found 

 that the red and blue fluorescent tints of glass which can 

 be produced by slow kathodic rays can also be caused by 

 NO. 2086, VOL. 81] 



sufficiently dense kathodic rays. For the blue fluorescence 

 it was shown that they are connected with the emission oS 

 negative electrons. A fixed point for the presence of the 

 positive electrons could not be ascertained. 



The experiments commenced in 1907 on the electrolytic 

 properties of silver and copper were concluded, and show 

 that silver in the aqueous solutions of HCl, HBr, and HI, 

 and copper in the aqueous solutions of HF indicate an 

 electrolytic valvular action which does not appear, as ia 

 the other metals, to be caused by a gas stratum, but by 

 a solid stratum. 



For the determination of the absolute values of standards 

 of self-induction, which are made by comparing with 

 capacities measured absolutely, a standard air condenser 

 was constructed. The new air condenser consists of 107 

 magnalium discs of 20 cm. diameter, i mm. thickness, 

 and I mm. apart. It has a capacity of about 003 mfd. 

 Amber is used for insulating, the insulation resistance being 

 of the order 10" ohms. 



The work done in the magnetic laboratory includes a 

 comparison of the methods of testing magnetic materials 

 and experiments on initial permeability. An exhaustive 

 series of measurements of self-induction was carried out , 

 with high-frequency alternating currents, and papers bear- c 

 ing on this subject have been published. A rotating inter- 

 rupter for absolute capacity measurements by Maxwell's 

 method is described. 



.\ number of tests were made on various forms of flicker 

 photometer which could be used on a straight photometer 

 bench, with the view of determining whether the use of 

 the flicker photometer is to be advocated for tests. It was 

 found, however, that the flicker photometer offered to the 

 skilled operator no advantage over the usual method of 

 measurement as regards rapidity and certainty of adjust- 

 ment. 



Nearly seventy official and private paoers of a scientific 

 nature by members of the staff were published during 1908, 

 particulars of these being given in an appendix to the 

 report. 



ZOOLOGY AT THE BRITISH ASSOCIATION. 

 T} Y arrangement between the organising committees, the 

 presidents of the biological sections gave their 

 addresses at different hours, so as to make it possible for 

 members to attend them all. The address in Section D 

 was delivered by Dr. Shipley on Friday, August 27. 



The programme for Thursday, August 26, was opened by 

 Dr. E. Goodrich with a paper on the origin of the verte- 

 brates. The object of this paper was to show that none 

 of the theories of the origin of vertebrates hitherto brought 

 forward, deriving them from some existing class of the 

 invertebrates, was satisfactory, because the theories violated 

 the sound principles of phylogeny based on the combined 

 evidence of comparative anatomy and physiology, embryo- 

 logy and palaeontology. This evidence enables us to trace 

 back the Gnathostomcs to a primitive shark-like fish, th-; 

 Gnathostomes and Cyclostomes to a common form of mu''i 

 more uniformly segmented structure, and, finally, the 

 Cranlata and Cephalochorda to an ancestor of very simple 

 structure, without dermal skeleton and without pronounced 

 cephalisalion, whicli probably became extinct even before 

 the Silurian age. 



Mr. C. L. Boulenger followed with a paper on certain 

 subcutaneous fat-bodies in Bufo. These structures are to 

 be found in a number of diffeient species, and consist of 

 masses of adipose tissue situated at the junction of the 

 hind-limbs with the trunk. 



On Friday, August 27, after the presidential address. 

 Prof. H. Jungersen read a paper, illustrated by lantern- 

 slides, on the osteology of the Lophobranchil. The author 

 pointed out that the skeletons of these fishes have hitherto 

 been most unsatisfactorily examined, and the cranial struc- 

 tures, especially the suspensory apparatus, the gill-arches 

 and the scapular arch, have been incorrectly interpreted by 

 all prevL^us authors. In the skull, parietals and opisthotlcs 

 are wanting, the pterotics are greatly developed, reaching 

 below to the b.asioccipitat, and preventing the exoccipitals 

 from meeting the prootlcs. These two features, together 

 with the prolongation of the anterior part of the skull 

 (mescthmoid and vomer), the Lophobranchil have in 



