lU CEMIiKR 24, I90SJ 



NA TURE 



239 



a stai. iiient of his views as lo the aim and end of technical 

 training;. Mr. Day pointed out the value of the associa- 

 tion of the work of the science side of the institute with 

 the study of the artistic crafts and with the bearing of 

 scienre upon design. It was, in his opinion, of great value 

 to develop so far as possible a more intimate association 

 than (udinarilv exists between different branches of teach- 

 ing, so as to familiarise the craftsman with the methods, 

 the .lims, and the applications of science. Previous to 

 the distribution of the prizes, Mr. George Baker, chair- 

 man of the institute committee, in reporting on the work 

 of the past session, referred to the fact that the prizes 

 that had recently been presented to the institute by the 

 Goldsmiths' Company for the department of metallurgy 

 had been awarded for the first time. The first of these 

 prizes was given for the best piece of research work carried 

 on in the department of metallurgy during the past session, 

 and he recorded with great interest that three very satis- 

 factory investigations had been done during that period. 



The issue of the Oxford and Cambridge Review for the 

 Michaelmas term contains an unusually large number of 

 articles dealing with subjects connected with higher educa- 

 tion. Dr. F. C. S. Schiller discusses exhaustively the 

 whole question of scholarships at the public schools and 

 the universities under the title of " Eugenical Scholar- 

 ships." The particular title adopted is justified, because 

 the thorough examination of recent proposals to restrict 

 public scholarships to the children of poor parents leads 

 up to a consideration of the matter from the point of 

 view of eugenics. Intelligence and ability, says Dr. 

 Schiller, are hereditary ; the probability of getting able 

 children is vastly greater if they spring from able parents ; 

 intelligence and ability lead to success among professional 

 men ; for men so situated the institution of scholarships 

 is simply invaluable, since it acts as a great eugenical 

 inducement, and is calculated to augment the supply of 

 valuable citizens. Mr. R. J. MacKenzie, late rector of 

 Edinburgh Academy, in an article on school examina- 

 tions, points out how the multiplicity of examining bodies 

 all examining for similar purposes leads to waste of time, 

 money, and energv in secondarv schools, and pleads for 

 a universal " secoodary-schools' leaving examination " for 

 England and Scotland. The same issue of the Review 

 contains an essav entitled " The Idealistic Interoretation 

 of Prof. Ostwald's Theory of Energy," by Mr. J. Butler 

 Burke, and articles on other educational matters. 



SOCIETIES AND ACADEMIES. 

 London. 

 Royal Society, Tune 25, — " Dichloro-urea." By Dr. 

 F. D. Chattaway, F.R.S." 



There is probably no substance among the almost be- 

 wildering number known to chemists which surpasses urea 

 in interest, or which has been more frequently and care- 

 fully investigated. It has been so much studied from 

 almost every point of view that a new simple derivative 

 was scarcely to be expected. Such a new simple derivative 

 is, however, found in the recently discovered chlorine sub- 

 stitution product. 



This is produced when chlorine is passed into a cooled 

 saturated aqueous solution of urea. Action takes place 

 without any considerable development of heat, and a 

 compound crystallises out in which two of the four 

 hydrogen atoms of the parent substance are replaced by 

 ."lalogen. Dichloro-urea obtained thus is a soft, white 

 crystalline powder, consisting of thin transparent plates, 

 which can be preserved for a considerable time in a drv 

 atmosphere, although, as might be expected, it is not 

 verv stable. 



Having regard to its composition and mode of forma- 

 tion, as well as to the structure of urea itself, its consti- 

 Muist be represented by the formula 



>N-CO-X< 



CI 



which explains its formation and such of its reactions 

 as have yet been studied. From this structure, and the 



XO. 2043, VOL. 79] 



fact that heat is absorbed when it is formed, it might be 

 e.xpected to be highly explosive. When heated, however, 

 it does not itself explode, but decomposes at about 83° C. 

 with liberation of the vapour of nitrogen chloride. The 

 latter, if it is not allowed to escape, and if the tempera- 

 ture is raised a few degrees higher, detonates with great 

 violence. 



Dichloro-urea is a compound of a marked acid character ; 

 it has a sour taste, recalling that of hypochlorous acid, 

 and its aqueous solution strongly reddens litmus paper, 

 which only becomes bleached after the lapse of some 

 minutes. It acts very corrosively upon the skin, staining 

 it yellow and destroying the tissues, and gives all the 

 reactions characteristic of compounds in which chlorine 

 is directly attached to trivalent nitrogen. It is dis- 

 tinguished from most other substances belonging to this 

 class of compounds by the readiness with which it is 

 hydrolysed, nitrogen chloride, carbon dioxide, a little 

 nitrogen, and ammonium chloride being produced. 



Dichloro-urea is instantaneously decomposed by a solu- 

 tion of caustic potash, two-thirds of the contained nitrogen 

 being liberated as gas with violent effervescence, while 

 the remaining one-third appears as ammonia, which, 

 together with the alkaline carbonate also formed, remains 

 dissolved in the liquid. 



This behaviour of dichloro-urea gives an insight into 

 the course of the reaction which occurs when urea is 

 decomposed by an excess either of alkaline hypochlorite 

 or hypobromite. This decomposition, which has received 

 an extraordinary amount of attention, as it furnishes a 

 quick, though not very accurate, method of estimating the 

 quantity of urea present in a liquid, has never been 

 properly explained, and is generally represented by an 

 equation which makes it appear to be a case of oxidation. 

 Dichloro- or dibromo-urea or some analogous compound 

 is without doubt formed as an intermediate product, the 

 action being thus one of halogen substitution followed by 

 decomposition of the substituted urea by the excess of 

 alkali present. 



It may be noted that dichloro-urea is safe to handle, 

 and promises to be of considerable use as a synthetic agent. 



Royal Astronomical Society, December 11. ^Mr. H. F. 

 Newall, F.R.S., president, in the chair. — The determina- 

 tion of the apparent diameter of a fixed star : Major P. A. 

 MacMahon. But little certainty is to be attached to 

 existing estiinates of the diameters of fixed stars, and a 

 direct method, independent of the star's parallax, is much 

 to be desired. The author proposed to apply the principle 

 of the bioscope to the photography of occupations of stars 

 by the moon. It was shown that a star might have an 

 apparent diameter of i/ioooth of a second, and that the 

 time taken by the moon to occult a fairly bright star 

 might give an approximate measure of such a diameter. 

 Prof. Dyson said he entirely agreed with the principle of 

 Major MacMahon's method, and hoped that results might 

 be obtained in the case of bright stars occulted by the 

 dark limb of the moon. It would be necessary to employ 

 a reflecting telescope of large aperture, and extremely 

 sensitive plates. — The Astronomer Royal showed further 

 photographs of comet c 190S, Morehouse, in continuation 

 of the series exhibited at the last meeting, carrying the 

 record to November 25, after which the moon interfered, 

 and the comet got too low. The structure of the tail still 

 showed detail of great interest, including the apparent 

 dark rifts, though the cyclical changes seen in September 

 and October did not appear to continue. A further series 

 of photographs of the comet, taken by Prof. Barnard at 

 the Yerkes Observatory from October 16 to November 19, 

 was also shown. — The comet of 1556 : its possible break- 

 ing up bv an unknown planet into three parts, seen in 

 1843, 1880, and 1882 : Prof. George Forbes. The three 

 latter comets formed a group, closely related to e.ach other, 

 and the author gave his reasons for considering that the 

 disruption of the comet of 1556 occurred through the in- 

 fluence of an ultra-Neptunian planet, which his calcula- 

 tions showed to exist at a mean distance from the sun 

 of about too celestial units, with a period of about 1000 

 vears and an inclin.-ition to the ecliptic of about fifty 

 degrees. Some search had been made for the supposed 

 planet, but onlv in the region of the Zodiac, so it was not 

 surprising that the results had been negative. — An 



