May 14, 1908] 



NA TURE 



45 



lorestrv, and the professor and students have the advantage 

 of a forest nursery located in Earl Bathurst's park, a por- 

 tion of which he placed at the disposal of the college for 

 this purpose. 



The Board of Education has published (Cd. 4037) the 

 Regulations for English Secondary Schools for the year 

 beginning August i next. The regulations are in main 

 substance the same as those of last year. Owing to 

 difficulties which have arisen during the past year in the 

 interpretation of the regulations referring to the provision 

 of free places in secondary schools, these rules have been 

 further defined. It is made clear that boys and girls 

 applying for such free places may be required to pass an 

 entrance test of attainments and' proficiency, having due 

 regard to the age of the applicants, the subjects in which 

 they have been receiving instruction, and the standard of 

 attainments and proficiency required for the admission of 

 fee-paying pupils. Pupils who enter the school as bursars 

 or Du'pil teachers must not be counted in estimating the 

 nu er of free places provided. In examinations held for 

 ihe"^ selection of boys and girls to occupy free places, 

 importance is to be' attached to the report of the candi- 

 date's own teachers, and the masters or mistresses of the 

 secondarv school are to be associated with teachers familiar 

 with elementary-school conditions in conducting the 

 examination. The regulations make provision, too, for 

 greater elasticity in the way of adapting the instruction 

 to the requirements of the pupil, though precautions are 

 taken to see that this privilege is used with proper modera- 

 tion. To meet the difficulty of providing secondary educa- 

 tion in rural areas and less populous urban or semi-urban 

 districts, the Board is prepared next year to recognise 

 secondary schools with fifteen instead of sixteen as the 

 normal leaving age, but this concession is only made where 

 a consideration of local circumstances shows that it will 

 be of distinct educational advantage to the district, and 

 tliat a longer school-life is not under actual conditions 

 possible. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, June 27, 1907. — "On the Polymorphic 

 Changes of Ammonium Nitrate." By V. Behn. Com- 

 municated by Prof. A. Schuster, F.R.S. 



The main results of the research may be summarised as 

 follows : — • 



(a) From the dilatometric and cr5'stallographic work no 

 definite information is forthcoming which affords any 

 precise proof as to a difference in properties of the two 

 tetragonal modifications of ammonium nitrate. 



(h) The argument derived from the investigation of the 

 thermal properties tells, so far as it goes, against the 

 identity of the two tetragonal modifications, but it cannot 

 be considered as decisive. 



January 30, 1908. — " The Refractive Index and Dis- 

 persion of Light in Argon and Helium." By \\''. Burton. 

 Communicated by Prof. J. J. Thomson, F.R.S. 



The initial object of this research was to find the dis- 

 persion of light in the monatomic gases argon and helium, 

 but as it was necessary to know the absolute value of the 

 refractive index with considerable accuracy, determinations 

 of the refractive index were made. 



The results for argon and helium are tabulated below, 

 and, for comparison, Mascart's values for hydrogen are 

 also given. 



Refractive index, reduced to 0° C. and 760 mm. pressure 

 for D, line. 



Argon 



Helium 



Hydrogen (Mascart) 



Dispersion : — In equation 



H - I = I7| I + -'^ 



or ;? = A + ,, 



I -0002837 



ioooo3i;oo 

 1-0001387 



B 



i /I A B 



Arfon ... 5-6x10"" 0-0002792 1-0002792 i-6xio~''' 



Helium... 2-2x10"" 0-00003478 1-00003478 7-5x10""' 



Hydrogen 4-3x10"" 0-0001376 i -0001376 5-9x10"'" 

 (Mascart) 



NO. 201 I, VOL. j81 



It may be noted that the values of a;b for these sub- 

 stances are approximately in the ratio 3:1:2. 



February 13. — " The Efl'cct of Hydrogen on the Dis- 

 charge of' Negative Electricitv from Hot Platinum." By 

 Prof. H. A. Wilson, F.R.S. 



The view taken in this paper is that the effect of the 

 hydrogen on the leak is due to its presence in the surface 

 layer of the platinum. To explain this it is supposed that 

 the hvdrogen atoms in the layer are positively charged, 

 so that they diminish the charge per unit area in the 

 electrical double layer covering the surface of the platinum. 

 The hj-drogen appears to dissolve in the platinum at first, 

 but at high pressures in time forms a stable combination 

 with the platinum, having a very small dissociation 

 pressure. Before this compound has been formed, the leak 

 is proportional to a power of the pressure of the hydrogen. 



February 20. — " On the Dispersion of Gaseous Mercury, 

 Sulphur, i'hosphorus, and Helium." By C. Cuthbertson 

 and E. Parr Metcalfe. Communicated by Prof. F. T. 

 Trouton, F.R.S. 



In continuation of previous work on the refractive indices 

 of certain elements in the gaseous state, the authors have 

 measured the dispersion of the elements named above 

 within the limits of the visible spectrum. 



The results obtained may bo summarised as follows : — 



M-l=o-coi75S('' + r2~k)- 



Mercury 

 Sulphur 

 Phosphorus . 

 Helium 



A-ic 

 M- 1=0-001046^1 ^^.^l 



I 



= 0-0011621 I + ^^-, 



.•■'lo'V 



M- 1=0-0000347(^1 +^^y 



The dispersion of mercury is about four times that of 

 air. 



The index of sulphur for infinite waves is, within 2 per 

 cent., four times that of oxygen. Its dispersion is, not 

 so exactly, four times that of oxygen. 



The index of phosphorus, for infinite waves, is exactly 

 four times that of nitrogen. Its dispersion is almost 

 exactly twice that of nitrogen. 



The' index of helium is, within i-6 per cent., one-eighth 

 of the best existing value for the index of argon. Its 

 dispersion is about three-sevenths that of air. 



March 5. — " On the Electrical Resistance of Moving 

 Matter." By Prof. F. T. Trouton, F.R.S., and A. O. 

 Rankine. 



The question of relative motion between the earth and 

 the neighbouring ether has been under discussion for many 

 years. It has, from time to time, been the subject of 

 important investigations, but these have all resulted nega- 

 tively. The experiment described in the present paper is not 

 different from them in this respect, yielding, as it does, no 

 definite information on the main point. Indirectly, the aim 

 was to measure the direction and magnitude of ether-drift, 

 the actual method having been to attempt to demonstrate 

 the existence of the Fitzgerald- Lorentz shrinkage, which 

 has been supposed to mask the effect in the direct experi- 

 ments of Michelson and Morley, and of Trouton and 

 Noble. 



The results lead the authors to conclude : — 



(i) The total electrical resistance of a wire is not altered 

 by an amount exceeding 5x10-'° of the whole amount by 

 any change of its position relative to its motion through 

 space. 



(2) On the assumption that the Fitzgerald-Lorentz 

 shrinkage is a real effect, the specific resistance of a 

 material is dependent upon the direction of flow of the 

 current, being greater to a current flowing parallel to the 

 velocitv of the material through space than to a current 

 in a perpendicular direction. The magnitude of this change 

 of specific resistance is shown by the experiments to be 

 certainlv within 2 per cent, of being sufficient to com- 

 pensate the change of length. 



March 12.—" Bacteria as .Agents in the Oxidation of 

 Amorphous Carbon." By Prof. M. C. Potter. Com- 

 municated bv Prof. J. B. Farmer, F.R.S. 



Under conditions of exposure to the air, a slow oxidation 



