142 



NA TURE 



[June 7, 1906 



three nitrobenzaldehydes show that the colour of these sub- 

 stances is not due to their existence in the azo-form. — The 



' rusting of iron ; J. T. Nance. The " rusting " of iron in 

 solutions of ammonium chloride is probably due to the 

 action of hydrogen ions formed by hydrolysis of the salt. 



■ — Aromatic compounds obtained from the hydroaromatic 

 series, part ii., the action of phosphorus pentachloride on 

 trimethyldihydroresorcin : A. W. Crossley and J. S. Hills. 

 — Studies of dynamic isomerism, part v., isomeric sulphonic 

 derivatives of camphor : T. M. Lowry and E. H. Mag:son. 

 — The densities of liquid nitrogen and liquid oxygen and of 

 their mixtures : J. K. H. Inglis and J. E. Coates. The 

 results showed that a slight contraction tool< place on 

 mixing the two liquids. It was found that the solubility 

 of nitrogen in oxygen obeys Henry's law, but that the 

 solubility of o.xygen in nitrogen does not obey the simple 

 form of that law, since oxygen dissolved in nitrogen is 

 associated to the extent of about 9 per cent. — Glutaconic 

 and aconitic acids : H. Rogrerson and J. F. Thorpe. — 

 The chemistry of organic acid " thiocyanates " and their 

 derivatives : .A. E. Dixon. — The molybdilactate and the 

 tungstilactate of ammonium : G. G. Henderson. Molybdic 

 and tungstic anhydrides are dissolved, the latter with some 

 difficulty, when heated on the water-bath with solutions of 

 ammonium lactate, the products being ammonium molyb- 

 dilactate, MoO.ICjH.OjNHJ,, and ammonium tungsti- 

 lactate, W0,(C.,H,03NH,),, respectively. Descriptions of 

 these salts are given. 



Society of Chemical Industry (London Section), May 21. 

 — -\Ir. .\, (lordon .Salamon in the chair. — The electro- 

 chemical problem of the fixation of nitrogen : Prof. 

 Philippe A. Guye. Among the many investigations under- 

 taken to solve this problem, two directions have led to 

 Industrial methods, the one, calcium cyanamide, the other, 

 electrochemical nitric acid. The principal technical details 

 of the manufacture of calcium cyanamide are given, and it 

 is pointed out that its cost price depends upon that of 

 calcium carbide. From this it is concluded that a kilo- 

 gram of nitrogen fixed as calcium cyanamide will cost a 

 little more than ammonia salts and Chili saltpetre, if the 

 excess of calcium carbide obtained in carbide works not 

 available for the development of acetylene is used. This 

 conclusion seems confirmed by some agricultural tests made 

 with this new compound of nitrogen of which the value, 

 relative to Chili saltpetre, is not definitely fixed. Passing 

 to electrochemical nitric acid, the author summarises the 

 principles of its preparation, and although these are verv 

 simple, the application has presented serious difficulties, 

 which, however, now appear to be solved by the experi- 

 ments carried out in Norway. The absorption of the nitric 

 acid by sulphuric acid is insisted on, as this allows con- 

 ccntrated nitric acid to be directly obtained, which is of 

 greater commercial value than nitrate of lime, and con- 

 sequently of more interest to a new industry. Analysis of 

 the cost of electrochemical nitric acid leads to the con- 

 clusion that a kilogram of nitrogen is fixed slightly cheaper 

 as nitric acid than as calcium cyanamide. In concluding, 

 the author discusses the exterior economic factors which 

 may hasten the development of the nitrogen industries. 

 .Among these the direct synthesis of ammonia from nitrogen 

 and hydrogen, and the recoven.- of the nitrogen of coal 

 in the ammoniacal form by the methods of L" Mond are 

 mentioned. These processes, combined with the production 

 of electrochemical nitric acid, will in all probabilitv solve 

 the problem of obtaining electric energy cheaplv by 'motors 

 utilising the power of coal. 



Dublin. 

 Royal Dublin Society, April 24.— Prof. I. A. McClelland 

 m the chair. — Entoptic vision, part iv., Haidinger's brushes 

 and other entoptic phenomena : Prof. \V. F. Barrett, 

 F.R.S. The term entoptic vision mav be employed to 

 include the observation of all those phenomena the' cause 

 of which is situated within the eyeball. In previous papers 

 on this subject the author has shown how obscurities in 

 the path of a homocentric pencil of ravs within the eye 

 may be self-detected, delineated, and measured with great 

 ease by means of the cntoptiscope, a simple instrument 

 devised by the author. Obscurities due to incipient 

 -aiaract can be detected, and its progress watched and 

 NO. I9IO. VOL. 74I 



the effect of any possible remedy examined. In the present 

 paper the entoptic phenomena are studied, delineated, and 

 submitted to exact measurement, such as (i) the so-called 

 Haidinger's brushes, or coloured polarised fasciculi seen 

 when a brightly illuminated surface is looked at through 

 a Nicol's prism, and the seat of which has been the subject 

 of considerable discussion ; {2) the moving corpuscles, like 

 darting fire-flies, seen when a bright sky is looked at 

 through a cobalt blue glass. These are depicted and 

 measured in the paper, and the result leaves little doubt 

 that they are really due to the movement of blood cor- 

 puscles in the vessels of the retina, the curved streaks 

 of light they leave behind being due to the retention of 

 the image of a quickly-moving body. Other entoptic pheno- 

 mena are also discussed. — The absorption of (3 radiation 

 by matter : Prof. J. A. McClelland and J. E. Hackett. 

 It is important to know the true coefficient of absorption 

 of ;8 rays for different substances. There are really no 

 data on the subject, as the coefficient usually measured 

 depends to a large extent upon the power of the substance 

 to emit secondary j8 rays. This coefficient gives, there- 

 fore, little information as to the actual stopping power of 

 different forms of atoms. The present paper describes a 

 method of determining the true absorption coefficient. 



Royal Irish Academy, April 23. — Dr. F. A. Tarlelon, 

 president, in the chair. — Magneto-optic rotation : F. E. 

 Hackett. The author examines the two dispersion formulte 

 deduced by Drude for the magneto-optic rotation, and 

 brings forward e method to decide between them. The 

 analysis consists in deducing from the constants of the 

 formula, based on the hypothesis of rotating ions, the 

 quotient of the area of the ionic orbit by the period of the 

 ion for the absorption bands of carbon disulphide and 

 creosote. The radii of the ionic orbits thus obtained are 

 100 times the ordinary molecular radii. From this result 

 it is argued that the theory of rotating ions cannot account 

 for more than one-thousandth of the rotation observed in 

 these substances. A similar analysis applied to the con- 

 stants of the Hall effect formula leads to values of e »i 

 of the same order as are obtained for electrons. .Similar 

 results are shown to hold in general for diamagnetic sub- 

 stances. It is then concluded that the theory based on the 

 Hall effect gives a sufficient explanation of the rotation in 

 diamagnetic substances. — The total solar eclipse of -August 

 30, 1905 : A. L. Cortie. The observations recorded in 

 this paper were made at Vinaroz, on the Mediterranean 

 coast of Spain. The results were : — (i) the corona was of 

 the maximum type ; (2) there were numerous prominences, 

 especially one great group on the east limb of the sun ; 



(3) the lower corona was much disturbed over this group, 

 with a marked structure of arches and interlacing rings ; 



(4) a well-marked vortex-ring w'ith a white centre was 

 connected with the prominences ; (5) a ray, of presumably 

 dark matter, and a group of plumes, marked the south- 

 east quadrant : (6) the dark ray and plumes coincided in 

 position with the sun-spot regions, and were possiblv con- 

 nected with the area disturbed by the great February 

 spot; (7) some straight bright rays marked the south-west 

 quadrant, also in the region of the spot-zones ; (8) the 

 general trend of the streamers was north and south, the 

 largest streamers being placed almost at the south pole ; 

 (9) the inner corona was a ring of intense brilliancy, com- 

 parable to the full moon; (10) the streamers seemed in 

 general to mark the regions of prominences more than 

 those of spots. — Sixteen years' observations on the relation 

 of temperature and rainfall to the spread of scarlatina, 

 measles, and typhoid fever : R. Sydney Marsden. Weekly 

 returns of cases of these diseases and the corresponding 

 weekly variations of temperature and rainfall had been 

 recorded for the years 1890— 1905 at Birkenhead, and curve 

 diagrams had been worked out to show the relation of 

 the diseases to amount of rainfall and temperature as these 

 varied above or below their average normal amount. 

 .Atmospheric temperature was found to have no effect on 

 the spread of these diseases. As regards rainfall, this 

 was shown to have no influence whatever as regards 

 measles, but in the case of scarlatina the number of cases 

 increased after deficient rainfall and decreased after rain ; 

 the number of cases increases after a series of dry years. 



