228 



SCIENCE. 



[N. S. Vol. XIX. No. 475. 



for titration in alcoholic solutions, and of the 

 acid phthalates where aqueous solutions are to 

 be used. In the discussion following the read- 

 ing of this paper. Professor Coblentz spoke 

 highly of tartaric acid and acid potassium tar- 

 trate as standards for titration in aqueous 

 solutions. 



On the Structure of Metals and Alloys; 



Aluminium Alloys: William Campbell. 



Dr. Campbell, after describing the micro- 

 structure of the whole series of alloys of cop- 

 per and aluminium, and the change in struc- 

 ture due to casting, dwelt at some length on 

 the change which takes place in the solid state 

 in alloys containing over 84 per cent, copper. 

 It appears that the alloys solidify as solid 

 solutions, and at a lower temperature rear- 

 range themselves in a manner similar to that 

 of .the alloys of copper and tin between 68 and 

 75 per cent, copper, or of the carbon-iron 

 alloys containing up to 1.8 per cent, carbon. 

 Photographs of the alloys which had cooled 

 slowly were contrasted with those of alloys 

 which had been quenched from above the crit- 

 ical temperatures. On annealing the quenched 

 specimens, the original structure was restored. 

 The paper was illustrated by lantern slides. 



The Determination of Molyidenum in Steel: 



F. V. D. Cruser. 



Mr. Cruser described the analytical separa- 

 tion of molybdenum from iron and the rarer 

 metals now added in making steel, such as 

 chromium, tungsten, uranium and vanadium, 

 and the various methods used for the deter- 

 mination of molybdenum. In the course of 

 the work it was found that the separation of 

 iron from molybdenum by caustic alkali was 

 inaccurate, due to the formation of small but 

 variable quantities of ferric molybdate which 

 was soluble in alkali. A method was worked 

 out which is believed to be entirely accurate; 

 it is in brief as follows: Dissolve the steel in 

 nitrosulphurie acid; separate the molybdenum 

 as M0S3 by hydrogen sulphide under pressure ; 

 dissolve the sulphide and convert to sulphate; 

 reduce the molybdenum by zinc and reoxidize 

 by a standard solution of permanganate. If 

 tungsten is present the addition of three to 

 four grams of tartaric acid prevents its con- 



taminating the molybdenum sulphide. This 

 method was tested on a number of steels and 

 molybdenum alloys, and none of the metals 

 present was found to interfere, while by the 

 methods recently published the results were 

 unreliable in many cases, especially when 

 tungsten or vanadium was present. 



On the Determination of Nitrogen in Food 

 Materials and Physiological Products : H. C. 

 Sherman. Eead by title. 



H. C. Sherman, 



Secretary. 



DISCUSSION AWD CORRESPONDENCE. 



CONVOCATION WEEK. 



The multiplication of scientific and learned 

 societies is the normal outcome of the enor- 

 mous expansion in the fields of learning dur- 

 ing the past few decades. The farther one 

 pursues a single branch, say of science, the 

 more he becomes separated from those follow- 

 ing other branches of science. The scientific 

 society represents, like all other societies, the 

 grouping of those of similar tastes for mutual 

 profit and entertainment. As soon as a so- 

 ciety covers a field so large that many of the 

 matters brought before it are uninteresting or 

 unprofitable to any considerable number, the 

 society breaks up, either into new societies or 

 into sections, each with its own gatherings. 

 This fact was recognized early in the history 

 of the American Association. 



But specialization can be carried too far. 

 I do not mean merely that the man, mining 

 so industriously at the bottom of his own 

 shaft, is of little account to the rest of the 

 world, indeed, often forgets that there is any 

 world outside of his own hole. He himself 

 may recognize that this is true and not care 

 a whit, so that he discovers the truth for 

 which he is searching. What is of far more 

 importance is that in losing his sense of per- 

 spective he greatly hampers his own work. 

 He needs to know what others are doing that 

 he may gain a better conception of what he 

 himself is doing. 



We need the meetings of the special socie- 

 ties, and we need also the meetings of a gen- 

 eral society, where men come in contact with 



