July 4, 1878] 



NATURE 



269 



substances employed, viz., sodium salicylate, the benzoates, 

 phytolaccin, physostigma, eiion3rmin, sanguinarin, ipecacuan, 

 &c., have not hitherto been known to stimulate the liver ; and 

 definite information has now been obtained regarding the 

 influence of a number of other substances whose effects 

 have been hitherto altogether doubtful. He has also proved 

 that if a purgative agent has no direct stimulating power on the 

 liver it diminishes the secretion of bile, and the importance of 

 this fact is indicated. The results of the experiments which 

 were performed on dogs are in complete harmony with every fact 

 that has been perfectly ascertained in the human subject. The 

 experiments with every substance supply a precision of knowledge 

 regarding the effect of that substance on the liver which has not 

 previously existed. In indicating the place for such experiments in 

 medical science. Prof. Rutherford said : — " We all know how ex- 

 cessively complicated the analysis of the effects of drugs becomes 

 when they are administered to a bodily system distorted in its 

 action by the effects of disease. Of necessity the influence of a 

 drug upon a diseased state is the ultimatum of [pharmacology ; 

 and every experiment upon a healthy bodily system, whether of 

 man or animal, is merely ancillary to experiments with the 

 drug in disease. If we discover that a drug stimulates the 

 healthy liver of a dog, we do not conclude that it must also 

 stimulate the human liver in health, and still less do we con- 

 clude that it must have this action in disease. The experiments 

 on the healthy liver of the dog, on the normal and on the 

 abnormal human liver, are three sets of experiments, closely 

 related, but still distinct. The results of any one of the three 

 series cannot be substituted for those of the other two. Each 

 set of facts has its own proper place, and must be carefully 

 kept there. When, therefore, we show by our physiological 

 method of experiment that such a substance as sodium sali- 

 cylate or sodium benzoate powerfully stimulates the liver of a 

 dog, we do not for a moment say to the clinical observer — 

 You will find that these things act thus in man; but 

 we merely say this : Experiment with these agents on man, 

 and tell us whether or not you find that they stimulate his 

 liver, and tell us also in what diseased states you find the em- 

 ployment *of this or of that substance most advantageous. The 

 clinical experimentalist has a far more difficult task to discharge 

 than the physiological investigator, and he urgently requires all 

 the assistance that physiological methods can render him ; and 

 the more so because it is now admitted by all competent thinkers 

 that the actions of medicinal agents in diseased conditions cannot 

 be rightly understood unless we also know their effects in a 

 healthy condition of the bodily system." He further showed that 

 although therapeutics can never be brought within the sphere of 

 exact science, it is nevertheless very urgently our present busi- 

 ness not to fold our hands in a despairing nihilism, but to search 

 for every fact that can throw light on the function of every 

 bodily organ, the nature of its diseased conditions, and the 

 manner in which it is influenced by medicinal agents in its normal 

 and abnormal states ; and all we desire is that those who don't 

 comprehend our methods of procedure, although they are ever 

 ready and eager to profit by its results, will, instead of throwing 

 obstacles in our way, leave us to do what we can to alleviate not 

 only the sufferings of human beings, but also those of animals. 

 I At the conclusion of the paper Sir Robert Christison charac- 

 terised the professor's conmiunication as of the greatest im- 

 portance, and as one which would hand his name down to a 

 very distant future. The professor deserved the commendation 

 of the Society for his courage in going on, in spite of a senti- 

 *mental opposition, with his researches. He thought that the 

 time would come when the public would wake up from the 

 delusion in this regard in which it now was. Sir Wyville 

 Thomson, in intimating the thanks of the Society to Prof. 

 Rutherford, said that, in his opinion, if a man in a public 

 position felt that he had knowledge and nerve sufficient to per- 

 form these experiments for lessening the suffering and prolong- 

 ing the lives of men, even though they should involve a certain 

 amount of suffering to the lower animals, he was not only 

 entitled but was bound to peform them. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, May 16. — "On the Spectra of Metalloids. 



Spectrum of Oxygen." By Arthur Schuster, Ph.D., F.R.A.S. 



Commvinicated by J. Clerk Maxwell, F.R.S., Professor of 



Experimental Physics in the University of Cambridge. 



The many unexplained phenomena attending the passage of 

 electricity through gases will probably for some time to come 

 occupy the attention of experimental physicists. It is desirable 

 that the subject should be approached from as many different 

 sides as 'possible. One of oiu: most powerful instruments of 

 research is the spectroscope, but before it can be applied to the 

 study in question we have to settle the chemical origin of the 

 different spectra, which we observe in vacuum tubes, apd to 

 discuss in what way such spectra are liable to change under 

 different circumstances. I have chosen oxygen as a first subject 

 of investigation. Though Pliicker and Wiillner have, as far as 

 their experiments went, accurately described the phenomena seen 

 in oxygen tubes, the following contains much that is new, and 

 will put some of the older facts on a firmer basis. 



As some of the facts brought to light by the investigation bear 

 directly on the question of double spectra, our knowledge on that 

 point must be briefly referred to. We divide all known spectra 

 into three orders — continuous spectra, channelled space spectra, 

 and line spectra. With regard to continuous spectra, it is shown 

 that the older statement which limited them to liquid and solid 

 bodies is no longer tenable. Most gases give continuous spectra 

 long before they condense. Two theories of continuous spectra 

 are noticed. The one considers that the vibrations of a molecule 

 always tend to take place in a fixed period, but that the im- 

 pacts of other molecules may, when the pressure is great or in 

 liquid and solid bodies, prevent complete oscillations taking 

 place, and thus produce a continuous spectrum. The other 

 theory considers that, when a gas condenses, molecular combina- 

 tions take place, which make the molecular structure more com- 

 plicated, and may produce channelled space spectra or continuous 

 spectra. According to the latter theory such molecular com- 

 binations are possible before the gas condenses, and thus the 

 state of aggregation of the gas only indirectly affects the 

 spectrum. The latter theory seems to be more consistent with 

 experiment than the former one. For instance, it is shown that 

 oxygen gives a continuous spectrum at the lowest temperature at 

 which it is luminous. If the temperature be raised, the con- 

 tinuous spectrum is replaced by a line spectrum. This seems to 

 be inexplicable by theory of molecular impacts. 



The chief difficulty in the way of a complete investigation of 

 the spectrum of oxygen consists in the great distiurbing influence 

 of the presence of even a small quantity of any carbon com- 

 pound. Amongst a great many oxygen tubes which were filled 

 by various makers I only found one, which showed the spectrum 

 of pure oxygen ; all the others gave a spectrum of carbonic 

 oxide. It is therefore necessary in filling oxygen tubes to avoid 

 all greased joints and all india-rubber tubings. I have used a 

 Sprengel air-pump which communicated with the vacuum tube 

 by means of a ball and socket joint. The joint was kept air- 

 tight solely by means of strong sulphuric acid. The vacuum 

 tube was fused directly to the ball of the joint. To one end of 

 the vacuum tube a piece of hard glass tubing had been fused. 

 This was filled with different substances which, on heating, gave 

 off pure oxygen. The oxygen, therefore, came only into contact 

 with glass, mercury, and sulphuric acid, and the metal of the 

 electrode. Permanganate of potash, oxide of mercury, and 

 chlorate of potash, were used in turn, to prepare the oxygen, 

 but no effect was observed which could be traced to the sub- 

 stance used. The effect of the electrodes was eliminated 

 by varying the metals. Aluminiiun, platinum, silver, brass, and 

 iridium were used as electrodes. Any possible effect of the 

 glass was eliminated by finally repeating all experiments in a 

 glass receiver six inches in diameter, so that no part of the 

 spark came nearer than 24 inches to the glass. In this way it 

 is believed all possibility of error due to the presence of any 

 possible impurities was avoided. 



Four different spectra of oxygen must be distinguished. At 

 the lowest temperature at which oxygen becomes luminous it 

 gives a continuous spectrum. As the temperature is gradually 

 raised the continuous spectnmi is successively transformed into 

 two distinct Une spectra, which I call respectively the com- 

 pound line spectrum and the elementary line spectrum. It is 

 one of the principal objects of this paper to show that these 

 two line spectra which have been much mixed up together have 

 a separate existence. The generation of one always involves 

 the destruction of the other. The fourth spectrum is that which 

 is always seen in vacuum tubes at the negative pole. 



The Continuous Spectrum. — The following facts prove the 

 statement that at the lowest temperature at which oxygen is 

 luminous it shows a continuous spectrum. 



