September 20, 1884.] 



SCIENCE. 



321 



elements, appointed in 1882. There have been com- 

 pleted up to the present time, Ozone, by Professor 

 Leeds; Peroxide of hydrogen, by the same author; 

 The speed of chemical action, by Professor Warder; 

 Glucose, by Dr. E. J. Hallock; The action of heat on 

 metallic salts, by Professor Prescott; and about six 

 others are in progress. The co-operation of the 

 Smithsonian institution had been solicited by the 

 committees, in order to reach foreign chemists. The 

 section unanimously indorsed the action of the com- 

 mittee in the steps already taken. 



Prof. C. E. Munroe read a paper on examination 

 of the methods proposed for rendering the lighter 

 petroleum oils inexplosive. The author used alum 

 and ammonic chloride, and. found they were both 

 insoluble in the oil, and inactive. Camphor also was 

 used; and this reduced the flash-test, but made a 

 more explosive mixture with air than the vapor of 

 the original oil. 



Professor Atwater read a paper on the chemistry 

 of fish. Flounder is the least nutritive of fishes; 

 while the salmon, when fat, is the most nutritive. 

 Oysters, have least nutritive matter among the inver- 

 tebrates ; and northern oysters are more nutritive 

 than those from the south. The flesh of fish con- 

 tains less fat and more water than that of vertebrates. 

 Digestive ferments act upon the flesh of fish in the 

 same way as upon that of the vertebrates, about 

 ninety-eight per cent of the albuminoids being 

 digested in both cases. As ordinarily found, fish 

 gives from five to twenty per cent of edible matter. 

 A member of the British association asked if the 

 integument of the fishes had been examined. Pro- 

 fessor Atwater replied that he had confined his atten- 

 tion to the muscular tissues. 



Prof. F. P. Dunnington exhibited and described 

 a new form of gas regulator, depending upon the 

 expansion and contraction of a confined portion of 

 air acting upon a column of mercury. 



Professor Stewart made some remarks upon a new 

 process of manufacturing leather, by which the de- 

 pilitated hides are treated with sulphurous-acid gas 

 in closed vessels, the process being completed in 

 about twelve hours, producing a soft pliable leather. 



A discussion on valence was opened by Prof. F. 

 W. Clarke. He remarked that it was especially use- 

 ful in organic chemistry in explaining isomerism and 

 in synthesis. It was also useful in mineralogy; and 

 he mentioned as examples of isomerism the three 

 minerals kyanite, andalusite, and fibrolite, giving a 

 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 remarked, further, that valence was an attempt 

 to explain the arrangement of the atoms in a mole- 

 cule ; and spoke of the drawback 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 Professor 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 con- 



dition of organic chemistry before this question of 

 valence was appreciated. It was a working hypothe- 

 sis, a scaffold about a building, but not the building. 

 Hypothesis is not always the truth. Prof. W. Ram- 

 sey, of the British association, said that the difficul- 

 ties about valence could be traced to Lavoisier, who 

 worked upon stable compounds as oxides and chlo- 

 rides. 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 were well 

 illustrated in Sir William Thomson's effort to explain 

 them in complicated vortex evolutions. Mr. A. H. 

 Allen, of the British association, called attention to 

 the failure of chemists to recognize the value of the 

 work of John Newlands, in the periodic classification 

 of the elements usually ascribed to Mendeljeff. Pro- 

 fessor Greene remarked that it was best to consider the 

 cause of valence. Professor Ira Remsen testified to 

 the utility of valence. He remarked 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 use was 

 dangerous until they fully understood its meaning. 

 He believed that the value of valence had been mag- 

 nified, 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. H. Allen, of the 

 British association, said that many formulae that 

 showed the structure of compounds according to the 

 valence of the elements 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. Professor Dewar, of the 

 Royal institution, London, maintained that the 

 graphical method and structural formulae were most 

 useful, but they are often presented in a way that 

 shows an incomplete knowledge of the ideas of the 

 person who devised the formula. He remarked that 

 the text-books contained too many pictures of graph- 

 ical formulae, and that he considered it better to 

 follow the historical method for developing theory. 

 Professor Atwater thought that some idea of valence 

 should be given at the beginning, as it assisted the 

 student's memory. Prof. W. Ramsey, of the British 

 association, said that he was satisfied of the utility of 

 making the student perform experiments that brought 

 out facts to illustrate the theory of valence, and thus 

 understand its meaning from his own work. Pro- 

 fessor Caldwell said that he could not get along with 

 students in chemical analysis who had not obtained 

 some idea of the theory of valence. Professor Rem- 

 sen thought that the theory of valence might do some 

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

 sistance 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 



