Oct. 1 6, 1884] 



NA TURE 



599 



account of the many varying elements upon which it depends, 

 were clearly explained by a diagram, and the results given of 

 an approximation carried much further than ever attempted 

 heretofore. 



Prof. Harkness, in paying a high compliment to the celebrated 

 mathematician and astronomer for these laborious and valuable 

 researches, also expressed a wish that some of the B-dimen- 

 sional-space mathematicians would follow the example of Prof. 

 Adams, and apply some of their superfluous energy to the un- 

 solved problems in the solar system, which have some direct 

 practical bearing. 



Prof. Newcomb, in remarking upon the mass of the moon 

 used in this problem, expressed the opinio 1 that this could be 

 obtained most accurately by observations of the sun, in deter- 

 mining the angular value of the radius of the small circle de- 

 scribed by the earth about the common centre of gravity of earth 

 and moon, since this, in his opinion, seemed to be 'the only 

 constant which could be determined by observation absolutely 

 free from systematic errors, and hence was capable of an indefi- 

 nite degree of accuracy by accumulated observations ; and he 

 asked Prof. Adams's opinion on this point. 



The latter replied that he thought the quantity too small for 

 certain accurate determination, almost beyond what could be 

 actually seen by the eye in the instruments used. 



Prof. Newcomb admitted, in the case of absolute determina- 

 tions, the general impossibility of attempting to measure what 

 cannot be seen, but, in the case of differential or relative deter- 

 minations in which there was no supposed possibility of constant 

 or systematic errors, he advanced the theory, which he had some 

 thought of elaborating more fully at some time, that such deter- 

 minations might be carried by accumulated observations to a sure 

 degree of accuracy far beyond what can be seen or measured by 

 the eye absolutely. 



Prof. Adams hoped he would more fully elaborate and publish 

 this idea, since there was in it an element well worth careful 

 consideration. 



Prof. Harkness doubted the sufficient accuracy of meridian 

 observations of the sun, on account of the distortions produced 

 by letting the sun shine full into the instrument ; and spoke of 

 the difficulties in the transit of Venus observation ; from this 

 cause. 



Prof. Newcomb replied that he would have to show that this 

 would be periodic with reference to the moon's quarters in order 

 to affect this constant systematically. 



Prof. Adams then presented another note upon Newton's 

 theory of atmospheric refraction, and on his method of finding 

 the motion of the moon's apogee. 



In the Section of Chemistry papers were read by C. F. 

 Mabery of Cleveland, O., on chloropropiolic acid and some 

 derivatives of acrylic and propionic acids ; and by C. W. Dabney 

 on anhydrobenzamidosalicylic acid. 



Dr. Springer of Cincinnati exhibited some improved torsion 

 scales and b\lances. One of these had been used by Prof. F. 

 W. Clarke, and its action was spoken of as being very satis- 

 factory. 



Messrs. L. M. Norton and C. F. Presscott read a paper on 

 continuous etherification ; and Prof. Monroe detaled results of 

 analyses of an efflorescence on the bricks of some new buildings. 

 It was chiefly sodium sulphate. 



Mr. Clifford Richardson, in a paper on the chemistry of 

 roller-milling of wheat, stated that the dark colour of north- 

 western hard winter wheat could be overcome by using steel 

 rollers run at different speeds. 



Prof. Atwater has examined the nutritive value of different 

 fish. He finds flounder to be the least value, and salmon the 

 highest, and in invertebrates the oyster takes the lowest place as 

 a food-stuff. 



A lengthened discussion took place on the subject of valence 

 in chemistry. Prof. Clarke remarked that it was especially 

 useful in organic chemistry in explaining isomerism and in syn- 

 thesis. It was also used in mineralogy ; and he mentioned as 

 examples of isomerism the three minerals kyanite, andalusite, and 

 fibrolite, giving the structural formula for each. He then took 

 up the questions of variable valence, invariable valence, and 

 maximum valence as points that might be discussed. He re- 

 marked, further, that valence was an attempt to explain the 

 arrangement of the atoms in a molecule, and spoke of the draw- 

 back of being obliged to represent them on a plane surface, space 

 of three dimensions being much nearer the true state of affairs. 



Prof. B. Silliman remarked that the last statement of Prof. 

 Clarke was the key to the whole difficulty about valence. A 

 plane surface is insufficient to explain the facts. He testified to 

 the great utility of valence, and spoke of the chaotic condition 

 of organic chemistry before this question of valence was appre- 

 ciated. It was a working hypothesis, a scaffold without a build- 

 ing, but not the building. Hypothesis is not always the truth. 



Prof. W. Ramsay said that the difficulties about valence could 

 be traced to Lavoisier, who worked upon stable compounds, as 

 oxides, chlorides. He also thought that a study of the heat of 

 formation of many compounds would be a key to the valence of 

 the elements ; and said that the difficulties of conceiving of the 

 motions of the atoms was well illustrated in Sir William 

 Thomson's effort to explain them in complicated vortex 

 evolutions. 



Mr. A. H. Allen called attention to the failure of chemists 

 to recognise the value of the work of John Newlands, in the 

 periodic classification of the elements usually ascribed to 

 Mendeleeff. 



'Prof. Greene remarked that.it was best to consider the cause 

 -if valence. 



Prof. Ira Remsen testified to the utility of valence. He re- 

 marked that there were two ways of teaching : one by giving 

 all the principal theories first, and the other giving the facts and 

 then the theories — which latter he considered the best method. 

 He had come to the conclusion that valence should never be 

 mentioned until all the important properties of a compound are 

 known. In regard to its value to young students, he thought 

 its u e was dangerous until they fully understood its meaning. 

 He believed that the value of valence had been magnified, and 

 that it was better to study the reactions of compounds, and the 

 methods for their synthesis, and the manner of breaking up. 



Mr. A. II. Allen said that many formulae that showed the 

 structure of compounds according to the valence of the ele- 

 ments do not give any idea of the true constitution of these 

 compounds as ascertained from a knowledge of their properties. 

 He gave, as examples of his meaning, potassic dichromate and 

 fuming sulphuric acid. 



Prof. Dewar, of Cambridge, England, maintained that the 

 graphical method and structural formula? were most useful, 

 but they are often presented in a way that shows an in- 

 complete knowledge of the ideas of the person who devised 

 the formula. He remarked that the text-books contained 

 too many pictures of graphical formula;, and that he con- 

 sidered it better to follow the historical method for developing 

 theory. 



Prof. Atwater thought that some idea of valence should be 

 given at the beginning, as it assisted the student's memory. 



Prof. W. Ramsay said that he was satisfied of the utility of 

 making the student perform experiments that brought out facts 

 to illustrate the theory of valence, so that he could thus under- 

 stand its meaning from his own work. 



Prof. Caldwell said that he could not get along with students 

 in chemical analysis who had not obtained some idea of the 

 theory of valence. 



Prof. Remsen thought that the theory of valence might be 

 some good as an assistance to the memory ; but such assistance 

 was of doubtful value, and too empirical. 



Prof. J. W. Langley, Vice-President, said that valence, or 

 chemism, may be a force emanating from the atom, or it may be 

 a force outside the atom ; it is static, or dynamic, and a know- 

 ledge of it was more a physical than a chemical problem. 

 From the educational view he thought it better to use the theory 

 of valence in connection with the history of the theories con- 

 cerning atoms and molecules. As a further step, the language 

 and figures of magnetism might be used. 



Prof Stewart described a process of making leather by treating 

 hides with sulphurous acid under pressure. 



Prof. Atwater has grown pease in washed sea sand, and found 

 them to gain from 35 to 50 per cent, more nitrogen than they 

 contained originally, and refers this increase to nitrogen directly 

 absorbed from the air. 



Dr. Springer, in a paper on fermentation, showed that a fer- 

 ment exists in the stems of tobacco plants which decomposes 

 nitrates and forms butyric acid from sugar solutions. 



Prof. Dewar spoke of the density of solid carbonic acid, which 

 he finds to be 1-58 to r6o. 



Other short communications were made by Prof. Munroe on 

 deliquescence ; on human milk, by Prof. Leeds ; on gas 

 analysis, by Dr. Elliott ; and on fish oils, by Mr. Allen. 



