328 Intelligence and Miscellaneous Articles. 



of turpentine, ether, chloroform — the phenomena assume the fol- 

 lowing form : — 



The surface-tension also diminishes with the increase of the 

 pressure under which the gas is placed ; the velocity of the dimi- 

 nution is also much greater at a low than at a higher temperature ; 

 but the surface-tension, instead of stopping at a minimum which 

 would be something characteristic of the liquid, falls rapidly ; and 

 at 0° C, under the pressure at which carbonic acid is liquefied, all 

 the liquids above mentioned, without distinction, have the surface- 

 tension of carbonic acid — that is, a tension equal to 4 - 6 — — •- , 



centimetre 



But can they in this state be regarded as the same liquids ? Xot 

 at all. Let us take water as an example. When it is saturated with 

 carbonic acid under the pressure of one atmosphere only, has it the 

 properties of pure water ? It has a different density, a different 

 coefficient of expansion by heat ; even the temperature of its 

 maximum density is changed. The changes which take place in 

 the liquids mentioned are much more considerable : we need only 

 observe what takes place with ether when it absorbs carbonic 

 acid under pressure. Its volume increases with such rapidity that, 

 although my method enables me to measure the surface-tension of 

 a liquid in a much shorter time than a minute, it is almost impos- 

 sible to take exact measurements in this case. 



It follows from all these facts that the phenomena described in 

 these Notes have absolutely nothing to do with pressure. The 

 diminution of the surface-tension of the liquids depends solely on 

 the circumstance that the surface-tension of carbonic acid, with 

 which they are compressed, is extremely slight. While the surface- 

 tension of water is equal to 80 -T ne nearly, and those of the 



centimetre 

 other liquids examined, with the exception of ether, lie between 32 



and 25 — J^r—, the tension of carbonic acid is on! v4-6 — yne . 

 _ centimetre ■ centimetre 



Capillary phenomena depend only on the molecular forces acting 

 at the surface of the liquid. Therefore it is not surprising that the 

 presence of a body which possesses so feeble a tension among the 

 particles of the liquid of which that surface-layer is composed 

 exerts an influence upon the resultant of all those forces — that is to 

 say, upon the surface-tension. 



The same mode of reasoning applies to the case of a liquid being 

 compressed with a much less liquefiable gas than carbonic acid — 

 such as oxygen, nitrogen, or hydrogen ; for the more difficult it is 

 to liquefy those gases the less must be their surface-tension. The 

 effect of the compression will depend only on the value of that ten- 

 sion and on that of the solubility of the gas. — Comptes Rendus de 

 VAcadimie des Sciences, August 14, 1882, t, xcv. pp. 342, 343. 



