70 



NATURE 



{_May 20, 1880 



lines. Mr. Jolly here pointed out tlie position of the suc- 

 cessive contractions of the ice required to dam the lake, and 

 described the abundant evidences of this last stage of the glaciers 

 there, in scratchings, carried blocks, boulder clay, &c., and in 

 the splendid horse-shoe moraines of the Treig glacier, lying 

 intact across and along Glen Spean. He held that the lowe t 

 road extended up Loch Treig only a short di-tance, suddenly 

 ceasing there, and not round the whole lake — an additional 

 remarkable proof in favour of a glacier then filling that basin 

 down to the ends of the roads, where a dam was necessary. 

 Similar remarks were made regarding the Glen Gluoy and Glen 

 Laggan parallel^. 



By means of coloured additions laid over the map, the state of 

 the ice at this period, necesfary to fulfil the requisite conditions, 

 was graphically exhibited. Mr. Jolly concluded with an appeal 

 to the Society to study the fascinating proiileai on the ground 

 itself, so as to help to a final settlement of the much-debated 

 question. Inverness had already done honourable work in con- 

 nection with it, for the height of the lowest road had been first 

 determined by an Inverness man, Mr. Wm. Paterson, sent there 

 for 'he purpose in 1847 by Mr. Joseph Mitchell, at the request 

 of Mr. Robert Chambers. 



Mr. Home, of the Geological Survey, Banff, and others, after- 

 wards spoke on the subject, and a cordial vote of thanks was 

 awarded to Mr. Jolly. 



The reader may consult with advantage, for the better under- 

 standing of the subject, the admirable maps of the district of the 

 Ordnance Survey, both the six- and one-inch, in which the 

 Roads and the related phenomena are accurately and fully laid 

 down ; or the special Ordnance selected map of the locality, 

 appended to the paper of Sir Henry James, mentioned above. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



Cambridge. — The authorities of both Girton and Newnham 

 Colleges have supported the general memorial of 8,500 persons 

 in favour of the admission of women to academical degrees and 

 examinations, by informing the Senate in detail of their past 

 proceedings, the number of their students w ho have been ex- 

 amined informally, none of whom have failed to attain Tripos 

 standards ; and both colleges believe that they will be able to 

 offer sufficient guarantees of stability and good administration, 

 so that the University can admit their students to full academical 

 privileges. 



Newnham College has now been fully constituted, with Prof. 

 Cayley as president. Prof. Adams has ably aided the Women's 

 Educational Association during the last seven years as president, 

 and now retires, on the amalgamation of Newnliam Hall with it, 

 retaining his place on the Council. 



Mr. K. C. Rowe, of Trinity College, is appointed an Examiner 

 in the next INIathematical Tripos, and Mr. A. G. Greenhill 

 Additional Examiner. 



Dr. Alexander Dickson has been appointed Regius Professor 

 of Botany in the University of Edinburgh and Keeper of the 

 Royal Botanic Garden of that city in succession to Dr. Balfour, 

 who resigned some time ago. 



The new representative Council of Education in France has 

 been completed by the appointment of a number of oiticial 

 members. M. Berthelot has been nominated President by the 

 Ministry. A number of sections and special commissions have 

 been established, amongst which we must direct attention to the 

 Commission for Reforming Secondary Instruction. One of the 

 principal features of the intended reform is to divide secondary 

 instruction into three different courses, so that any pupil leaving 

 the school after having gone through the elementary course 

 might have a general knowledge of the principal subjects w hich 

 are to be investigated more fully in the other two courses. 



The University of the City of Pesth celebrated its hundredth 

 anniversary in presence of the Emperor on the 13th inst. 



SCIENTIFIC SERIALS 



AnnaUn der Physik mid Chcmie, No. 4. — On the propagation 

 of electricity through current water in tubes, and allied pheno- 

 mena, by E. Dorn. — Thermic theory of the galvanic current, by 

 J. L. Hoorweg. — On the cause of excitation of electricity in 

 contact of heterogeneous metals, by F. Exner.— On diffusion of 

 salts in aqueous solution, by J. H. Long.— On the relation 

 between propagation of light and the density of bodie-, by II. A. 



Lorenz.— On Stokes's law, by O. I.ubarsch.— On after images 

 of motion, by G. Zehfuss. — Supplementary note to the p.iper on 

 currents of t!;e Gramme machine, by O. E. Meyer and F. 

 Auerbach. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, April 29.— " Measurement of the Ac'inism 

 of the Sun's Rays and of Daylight." By Dr. R. Angus Smith, 

 F.R.S. 



When examining the air of towns and the effect of smoke and 

 fogs, I have often wished for a very simple chemical method of 

 measuring the total light absorbed by these gases, vapours, and 

 floating solids. I do not undervalue the work of others, but I 

 think I have obtained a process promising good results with ) 

 great simplicity, although I daresay it introduces its own class ot 1 

 difhculties. 



1. The fundamental fact is that when iodide of potassium in 

 solution is treated with nitric acid, so small in quantity as to 

 cause no change of colour in dull diffii^ed light, a change takes 

 place when the same mixture is brought into clear light ; iodine 

 is set free and the solution becomes yellow. 



2. The amount of iodine freed can be titrated with great 

 exactness by the use of hyposulphite, as is well known. 



In these two facts lies the whole process : the first is the new 

 part, the second makes the first quantitative, and its use is of 

 course part of the novelty. 



3. It is known that strong .acid hberates iodine. Weak acid 

 does so after a long time, but the process is hastened by light. 1 



4. Pleat even to the boiling point does not act so well as light 

 (experiments being made in sealed tubes to prevent loss of 

 iodine, and with a considerable volume of air). 



5. Heat assists the action of light. 



6. A solution may be exposed day after day so as to give the 

 accumulated effect of sunlight, in a measurable condition at the 

 end of the time. 



7. The solution of iodide of potassium as hitherto obtained is 

 subject to change. An old solution, that is, one nearly a month 

 old, was found more sensitive than a new one in all cases tried. 



8. The result of No. 7 is, that a certain allowance may require 



to be made for this, in those cnses where the periods of observa- ' 

 tion with one solution are long. 



9. The amount of allowance to be made for temperature is ' 

 not made out. It is not certain that any is required in the cases \ 

 when weak acid is used. The weather has not allowed any ■ 

 combined action of great light and heat, but with heat and light ' 

 iu the rays from an electric light with a parabolic reflector, the 

 action was very rapid, 



10. Specimens of experiments (prospective at first). It was 

 found convenient to use a solution of 2 grms. of iodide of potas- 

 sium, afterwards changed to i grm., in 100 of water, and to use 

 half of this for an experiment, i.e., 50 cub. centims. of the 

 solution, which may be called A. 



A nitric acid solution having an acidity equal to I per cent, of 

 sulphuric anhydride was made ; this may be called B. Only 

 very small portions of B were added to A. 



Examples in which the decomposition was measured by a 

 solution of hyposulphite of sodium, which maybe called solution ' 

 C = o"l grm. per litre of iodine (or as convenient). I shall 

 extract experiments made with B solution O'S cub. centim., 

 because it is an intermediate one ('2, '4, "S, i '6, and 3'2 have \ 

 hitherto been the favourites). 



