TRANSACTIONS OF THE SECTIONS. 75 



CHEMISTET. 



Address hy "W. A. Miilt?e, M.D., F.R.S. SjX., Professor of Chemistry, 

 Kiny's CoUeye, London. 



In opening the proceedings, the President said that in the home of Dalton, in 

 the focus of applied cliemistry, veiy few words would be necessary. They could 

 not but remember that, on the last occasion when the Meeting of the British Asso- 

 ciation was held in Manchester, that Ulustrious philosopher was still amongst them ; 

 and he trusted that the same spirit which actuated Dalton still remained in Man- 

 chester to enlighten his native coimty. Without saying more by way of intro- 

 duction, he would call their attention to one or two points of progress diuing the 

 East year. In calling attention to these subjects, he must necessarily refer to de- 

 atable groimd in science, — but it was in debatable land that progress was neces- 

 sarily made. He would only touch upon two or three practical applications of 

 chemistry, and two or three theoretical ideas which had been propomided since 

 they last met. The Professor then alluded to the new methods of preparing 

 oxygen and hydrogen, proposed by Deville, which admit of application on such 

 a scale as to allow of the generation of oxygen for manulacturing purposes, 

 and the employment of the oxyhydrogen blast as a soui-ce of heat in metal- 

 lurgical operations. The novelty in tho preparation of oxygen consists in decom- 

 posing the vapour of sulphuric acid, and, by a fiu'ther process, storing up the oxy- 

 gen in gas-holders. The preparation of hydrogen required more care. Ihe metal- 

 lurgy of platinum had already experienced a remarkable modification, owing to tho 

 application of the intense but manageable source of heat obtained by the combus- 

 tion of these gases. In connexion with oxygen might be mentioned a singadar 

 circumstance regarding ozone, which, according to the obsei-vation of Schrotter, 

 had been found in a pecidiar species of fluor spar, from Wolsendorf, which, when 

 nibbed or broken, emitted a pecidiar odoiu- of ozone. The active chemist DeviUe, 

 in foUovring his researches, had discovered a variety of means of obtaining artifi- 

 cially, crystallized minerals of great regvdarity and beauty. The methods adopted 

 were chiefly by heating the amorphous substances in a slow current of some gas, 

 such as hydrochloric acid, which was not an unfrequent natural product in volcanic 

 districts. No discovery, however, had made a gi-eater impression upon the popular 

 mind than that of the remarkable alkaline metals cassium and rubidium by Kirch- 

 hoff' and Bimsen. These eminent men, in investigating the appearances presented 

 by flames coloured by various metallic salts when analysed by the prism, were led, 

 from the appearance of certain bright lines in the spectra, produced whilst they 

 were examining a saline residuum from the waters of the Diirkheim spring, to 

 infer the existence of a substance hitherto imknown. It was found that caesium 

 was present in such minute quantity, that a ton of that water, which was the most 

 abimdant source of ctesimn yet known, contained only 3 gTains of its chloride. 

 Taking into account the minuteness of the quantity, and its striking resemblance 

 to potassium, it was not too much to say that the discovery of coesiimi would have 

 been impossible by any other known method than that which was actually em- 

 ployed. The other metal, rubidium, was somewhat more plentifid ; but rubidium 

 also so closely resembled potash that it would not have been discovered but for 

 the peculiarity of its spectrum. lieferring to the revision of the atomic Aveights of 

 sulphur, sUver, initrogen, potassium, sodium, and lead, by Stas, Professor Miller 

 said that chemist had come to the conclusion that it was not proved that the ele- 

 mentary bodies were midtiples of the unit of hydrogen, and, in opposition to the 

 opinion of Dumas, he had pronounced the law of Prout as imaginary. Every 

 chemist would read with interest the paper by Graham iipon the application of 

 liquid difiiision to analysis. The remarkable conclusion to which the author arrived 

 was, that the process of difiiision separated all substances into one or other of two 

 classes, which he distinguished as crystalloids and colloids. The rapid improve- 

 ment in the method of analysis, though not admitting on that occasion of detailed 

 mention, must not be overlooked. A variety of bodies, formerly supposed to be of 

 rare oceun-ence, were now foimd in minute quantities, unexpectedly, but widely 

 diflused. The discovery of these small quantities was by no means unimportant, 

 for they might aid in solving problems of great interest. Glanciag only for a 



