530 



NA TURE 



[September 2S, 1893 



of sunlight as determined by the liberation of iodine does not 

 increase. 



The Report of the Committee on the Action of Tight on the 

 Hydracids of the Halogens in the presence of Oxygen was 

 read by Dr. A. Richardson. The committee have been inves- 

 tigating the conditions necessary to start the decomposition of 

 hydrochloric acid in presence of oxygen. Experiments show 

 that the presence of metallic salts is of great influence in this 

 respect ; the action of metallic chlorides is being especially 

 studied. 



The Expansion of Chlorine and Bromine under the influence 

 of Light was shown on the screen by Dr. Richardson. For the 

 success of the experiment it is necessary that the surface ten- 

 sion between the liquid, used as indicator of the expansion, and 

 the tube in which it moves, should not be great. 



Some interesting experiments made to determine the Rate 

 of Evaporation of bodies into Different Atmospheres were de- 

 scribed by Dr. Phookan. From the results obtained with 

 naphthalene, it appears that vapours behave quite differently 

 to gases in the manner in which they affect the rate of evapora- 

 tion of this substance into them. 



At the Monday sitting, Prof. P. Frankland read a paper 

 introducing a Discussion on the Present Position of Bacteri- 

 ology, more especially in its relation to Chemical Science. 

 Prol. Frankland said that the piesent science of bacteriology 

 really dated from the discovery, some twelve years ago, of 

 methods for obtaining pure cultures. Since then the changes 

 which have taken place have been chiefly in the methods em- 

 ployed for the recognition of bacteria. Microscopical charac- 

 teristics, even when they have been brought out by mordant 

 staining, have been found to be insufficient for this purpose. 

 This was illustrated by the case of the cholera spirillum, as 

 much difference existing between the different specimens of 

 this spirillum, as between it and totally different species. Mor- 

 phological have consequently been obliged to give way to 

 chemical and physiological tests. Chemical tests being as yet 

 few in number are apt to be treacherous, but they are capable 

 of considerable extension. The typhoid bacillus, e.g., will give 

 no reaction with indol, the characteristic of the cholera bacillus, 

 nor will it ferment glucose, but it will coagulate railk. With 

 regard to the chemical products of the action of organisms the 

 following questions suggest themselves : — Does the same sub- 

 stance yield different products with difi'erent bacteria? Do 

 the same bacteria give rise to the same products with different 

 substances ? 



Experiments with pure cultures have shown that one and 

 the same bacillus will give identical products with such 

 chemically related bodies as glycerol, arabinose, mannitol, &c. 

 It appears probable that fermentability is due to the power 

 possessed by a set of substances of yielding the same inter- 

 mediate body which will give identical end products in all 

 cases. This may explain why only those sugars which contain 

 three carbon atoms or a multiple of three in their molecule 

 appear to be fermentable. 



The production of all three varieties of lactic acid by fermen- 

 tation of glucose by different organisms has been accomplished. 

 The mechanism of their formation was discussed in the light of 

 Emil Fischer's formula for the glucoses. 



The problems of selective fermentation were next dealt with, 

 the cause of which was to be sought for in the slight differences 

 of solubility &c. , shown by active substances, when in com- 

 bination with optically active isomeric bodies. One isomer is 

 not found always to be quite unlermentable ; in some cases both 

 isomers can be destroyed if lime be allowed, one, however, 

 always disappearing first. 



Of great interest is what may be termed educational culture, 

 by means of which new characteristics may be artificially im- 

 pressed upon an organism. A species of bacillus, morphologi- 

 cally identical with anthrax, but totally incapable of producing 

 spores, maybe obtained by cultivation of true anthrax in broth 

 containing certain salts, such as potassium dichromate, or 

 nitrate. The new characteristics will even persist after passage 

 through the bodies of animals. On the other hand, by various 

 means the virulence of pathogenic organisms can be greatly in- 

 creased, though it has not been found possible to produce 

 pathogenic from non-pathogenic organisms. It becomes pro- 

 bable, therefore, that naturally occurring bacilli will acquire new 

 characteristics according to alleialions in their condition of 

 growth. The occurrence of non-toxic associated with, and morpho- 

 logically identical with certain toxic organisms, e.g. those of 



NO. I 24S, VOL. 48] 



diphtheria, anthrax, cholera, and typhus, is suggestive in this 

 connection. 



It is possible that aerobic organisms may become so far modi, 

 fied as to be active in absence of air. Much study is wanted 

 in this direction, which affords special opportunities for observ- 

 ing the conditions of evolution among simpler forms of life. 



The application of bacteriology to hygienic matters was next 

 dealt with, with special reference to the bacteriological exam- 

 ination of water. 



Finally, the disinfecting action of light under different condi- 

 tions was spoken of. The generation of hydrogen peroxide, 

 Irom air and moisture, under the influence of light, discovered 

 by Richardson, would seem to play an important part in this 

 action of sunlight, and the problem partly resolves itself into 

 the study of the conditions of formation of this substance. The 

 effect ot different salts in modifying the bactericidal effects of 

 sunlight was touched on, and in conclusion the necessity was 

 urged upon chemists of a knowledge of biology and botany, to 

 enable them to carry on bacteriological work, tor which the first 

 necessity had now become profound knowledge of chemistry and 

 chemical methods. 



In the course of the discussion, which owing to the length 

 and comprehensiveness of the paper was not prolonged. Prof. 

 Burdon-Sanderson advocated the establishment of an institute 

 for research where chemists, biologists, and pathologists could 

 mutually assist one another. It was resolved that, with his 

 permission. Prof. Frankland's paper should be published io 

 full. 



The following papers were read in connection with the subject 

 of discussion, viz., "Remarks on the Chemistry of Bacteria," 

 by R. Warington, F.R.S. ; " Fermentation in connection with 

 the Leather Industry," by J. T. Wood; and "Some Ferments 

 derived from Diseased Pears," by Dr. G. Tate. 



On the Tuesday morning. Prof. H. 1!. Dixon opened what 

 proved to be a most interesting discussion on Explosions in 

 Mines, with special reference to the Dust Theory. 



Opinions on this subject may be grouped under three 

 heads : — 



(1) That although it is possible to stir up and ignite a cloud 

 of dust, the flame dies out and is not explosive; i.e. that a 

 mixture of coal-dust and axx fer se is not explosive. This is the 

 view held by Mallard and Le Chatelier. 



(2) That, although a mixture of coal-dust and air per se is not 

 explosive, a very slight addition of fire-damp, insufficient to be 

 recognised by the Davy lamp, will render the mixture exphisive. 

 This view is supported by the experiments of Abel. 



(3) That a mixture of fine coal-dust and air is per se explosive, 

 and that the explosion once started in such a mixture CE^n be 

 propagated as far as the mixture extends. 



Prof. Dixon then gave a brief history of the subject, dealing 

 chiefly with the characteristic features presented by certain 

 great mine explosions, and the experiments and results of the 

 committees in different countries who have studied the question. 

 The explosion in the Seaham Colliery in 1S80 was specially 

 dealt with. By means of a diagram it was shown that the only 

 portions of the mine untouched by the explosion were those 

 which were damp, and therefore free from dust. It was im- 

 possible to explain the method of propagation of this explosion 

 otherwise than by the dust theory. Mr. Hall's experiments in 

 1891, in which a cannon was fired at the bottom of an old shaft 

 in which coal-dust was suspended, were described, and photo- 

 graphs of some of the explosions shown. In some cases ex- 

 plosions could be brought about by these means, in others not, 

 suggesting that the explosion was largely dependent on the 

 characterof the coal-dust. In conclusion, the importance of care- 

 fully testing for low percentages of fire damp was pointed out, 

 and also the possible advisability of using the fuses containing 

 ammonium nitrate, recommended by the French Commission, on 

 account of their low temperature of detonation. 



At the conclusion of Prof. Dixon's .address, Prof. Clowes 

 exhibited his portable safety lamp, with hydrogen attachment 

 for delicate gas-testing, described in ilie Proceedings of the 

 Royal Society, vol. lii. 



Mr. Galloway followed with a vigorous defence of the coal- 

 I dust theory. The dusty mines are always the deep mines which, 

 owing to their greater warmth, are dry. In no mine of a less 

 depth than 600 leethas any great explosion occurred. In damp 

 mines explosions are limited in their area, while in dry niines 

 they may ramify sometimes for a mile or so. In his opinion 

 the experiments which had given rise to the belief that stone 



