236 Intelligence and Miscellaneous Articles. 



ON THE INFLUENCE OF THE QUANTITY OF GAS DISSOLVED IN A 

 LIQUID UPON ITS SURFACE-TENSION. BY S. WROBLEWSKI. 



It has long been known that the solution in a liquid of a gas 

 which is superposed to it diminishes the tension of its surface. 

 M. E. Desains observed, twenty-five years since, that the rise of 

 the meniscus terminating water at its contact with air was a little 

 less than that formed with hydrogen, and a little greater than that 

 formed with carbonic acid — that is to say, that it was lowered in 

 proportion as the gas was more soluble. I have found that, in all 

 the liquids which I have studied, the surface-tension in contact 

 with air is a little greater than in contact with carbonic acid. Lastly, 

 M. Quincke has shown that, in the case of ammonia and hydro- 

 chloric acid (which are highly soluble in water), the diminution of 

 the surface-tension increased with the quantity of gas dissolved. 

 On the other hand, a number of cases can be cited in which the 

 more or less complete absence of the faculty of absorbing gases is 

 always accompanied in a liquid by relatively great surface-tension, 

 and conversely. Thus liquids whose coelficient of absorption is 

 considerable (ether, alcohol, the oils) have a feeble surface-tension. 

 Saline solutions, which absorb much smaller quantities of gas than 

 water, have a greater surface-tension than the latter ; and their 

 tension increases with the quantity of the salt dissolved, while their 

 capability of absorbing gases diminishes. By reducing the surface- 

 tension of water by the addition of alcohol, the solubility of gases 

 in the mixture thus formed is increased. And mercury, which, of 

 all liquids, has the greatest superficial tension, is almost incapable 

 of absorbing gas. 



The study of the correlation between these two classes of pheno- 

 mena may be commenced, on the one hand, by determining the laws 

 governing the solubility of a gas in a liquid, and, on the other, by 

 measuring the surface-tension of a liquid in contact with a gas, the 

 solubility of which in the surface-layer of the liquid can be regu- 

 lated at pleasure by increasing or diminishing the pressure upon 

 the gas. These experiments are so much the more easy to perform, 

 as the saturation of the surface-layer of the liquid is effected instan- 

 taneously, and the tension, depending onby on the condition of that 

 layer, follows with the same velocity every change in the pressure 

 which determines the value of that solubility. 



Up to the present time no one has considered the question in 

 this light. On the contrary, it has been attempted to establish a 

 theory of liquids which, while based on the facts which militate in 

 favour of the existence of that correlation, denies the correlation 

 itself. That theory, attributing to pressure a direct influence upon 

 the surface-tension, leads to consequences at variance with the facts. 

 Thus Kuudt, having observed that the height to which a liquid as- 

 cends in a capillary tube diminishes in the same proportion as the 

 pressure upon the gas is increased, has drawn from this fact the 

 following consequences : — 



There is an influence of pressure upon surface-tension. The 

 observed diminution ought to be regarded as a tendency of the 

 liquid to pass into the gaseous state. If the compression could be 



