September 24, 1886.] 



SCIENCE. 



269 



ing of primordial matter termed ' protyle ' (analo- 

 gous to protoplasm), which contained within itself 

 the potentiality of all possible atomic weights. 

 The keynote of the presidential address by Profes- 

 sor Bonney to the geological section was contained 

 in the phrase, "the application of microscopic 

 analysis to discovering the physical geography of 

 bygone ages." In the biological section Mr. 

 Carruthers, the president, drew attention to the 

 past history of those species of plants which still 

 form a portion of the existing flora. Sir F. Gold- 

 smid, who presides over the geographical section, 

 took for his subject " The means of popularizing 

 the study of geography," a contribution to which 

 end is seen in an exhibition of appliances therefor, 

 open during the meeting. In the section of 

 economic science and statistics, Mr. J. Biddulph 

 Martin, in his presidential addi'ess, gave an expo- 

 sition of the claims of this subject to a scientific 

 status. In that of mechanical science, the presi- 

 dent, Sir James N. Douglas, dealt with the pecul- 

 iarly appropriate subject of lighthouses, since 

 probably the largest manufactories of lighthouse 

 apparatus in the world are to be found in Birming- 

 ham. Lastly, in the anthropological section, Sir 

 George Campbell recommended from the presi- 

 dential chair the systematic and scientific cultiva- 

 tion of man with a view to both physical and 

 mental qualities, — ' homi-culture,' in the same 

 sense as oyster-culture, bee-culture, etc. 



Turning to the general work of the meeting, it 

 may be remarked that there were, at its commence- 

 ment, between six hundred and seven hundred 

 papers to be read and discussed in these various 

 sections. Geology seems the most prolific, that 

 section being almost overburdened with work. 

 Two subjects for special discussion were selected 

 some months ago : 1°, ' The theory of color- 

 vision ; ' 2°, ' The nature of solution.' The latter 

 was confined to the chemical section, but the 

 former was conducted at a joint meeting of the 

 physical and biological ; and it was remarked at 

 the outset that on no previous occasion had two 

 sections held a joint discussion. The result was 

 so successful, that it is hoped this precedent may- 

 be followed. No formal papers were read, but the 

 subject was opened by Lord Rayleigh, who, in a 

 speech of some length, reviewed the theory from 

 the physical point of view. Colors might differ in 

 three ways, — brightness, freedom from dilution 

 with white, and hue : hence, from any four colors 

 and black, a match might be made. He insisted 

 very strongly on the distinction in effect between 

 mixing colors (or paints) and mixing lights. No 

 other known colors than red, violet, and green 

 were ' primary,' though it was possible that some 

 other unknown tints might be the real primary 



colors. In the so-called color-bhndness, color- 

 vision was usually twofold, or dichroic. All that 

 he said, however, involved the assumption (prob- 

 ably true) that a mixture is more complicated than 

 its ingredients. Dr. Konig of Berlin followed 

 with an account of a large series of very careful 

 experiments upon elementary sensations of color, 

 — an analysis of color-sensations without any 

 hypothesis, — which led him to the conclusion 

 that the views of Thomas Young as to color, 

 viewed in the light of modern experimental re- 

 search, were certainly true. Dr. Michael Foster, 

 speaking from the physiological point of view, 

 pointed out to the physicists the difficulty of ap- 

 plying their theories of color, and exi^ounded 

 Hering's theory, according to which colors might 

 be divided into pairs, one of which produced as- 

 similation in the substance of the retina, and the 

 other dissimilation, such as blue and yellow, red 

 and green, and so on. Mr. J. Tennant pointed 

 out that both Hering's and Young's theories had 

 three independent variables, and led to the same 

 general results. As, however, Hering's unques- 

 tionably explained the phenomena of simultaneous 

 contrast best, he preferred it on that ground. The 

 discussion came to a premature end, from lapse of 

 time. That upon the nature of solution was 

 opened by Dr. Tilden, who had studied the subject 

 mainly from the point of view of the thermal phe- 

 nomena occurring at solution. He presented an 

 able summary of our knowledge of the subject, 

 and showed that the solubility of a salt depended 

 mainly on its melting-point, as well as on simi- 

 larity of constitution between it and the solvent. 

 Dr. Nicol showed experimentally that the mole- 

 cules of a salt stood in the same relation to all the 

 molecules of the water in which it was dissolved, 

 or, in other words, that salts did not retain their 

 water of crystallization in solution. Dr. Arm- 

 strong, Mr. Hartley, and Dr. Gladstone, however, 

 differed from this view, considering that the 

 hypothesis of 'residual aflSnity,' broached by 

 Helmholtz, afforded a sufficient explanation of 

 observed facts. 



At one of the general evening meetings. Profes- 

 sor Rucker delivered a brilliant lectxire to a very 

 large audience, upon ' Soap bubbles.' The ex- 

 perimental illustrations, all of which were pro- 

 jected on a screen by the electric hght, were of 

 exceeding beauty and invariably successful. The 

 particular point brought before the audience was 

 the thickness and other properties of the black 

 film of the bubble. The unit of measurement 

 employed was the millionth of a millimetre. It 

 was shown that this thickness varied considerably, 

 but that the optical and electrical methods of 

 measurements agreed closely in any particular 



