174 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



parting of the films ; 2cl, tbat the ebullition phenomenon was 

 present in all the cases observed; 3d, that decrease of press- 

 ure or movement of the air in contact with the surface ac- 

 celerated the formation of the film ; 4th, that heat may in- 

 crease the rapidity of expansion, or may stop it entirely, ac- 

 cording to the conditions ; 5th, that the ebullition disappears 

 as the development of the film is more rapid ; 6th, that no 

 contractile liquid surface is necessary for this expansion, 

 since it may take place within a mass of liquid or on the sur- 

 face of solids. Closer microscopical examination showed that 

 whenever a drop expands to a film, there is a development 

 of gas, appearing to the eye under the form of round swell- 

 ings, which move under the film from the thinner border to 

 the centre, and reveal their true nature if the film becomes 

 thin enouoh to break and allow them to be difi'used. The 

 phenomenon is well seen when almond oil is placed on a 

 glass disk. Moreover, the appearance of ebullition above re- 

 ferred to arises from this development of gas, the two or 

 three bubbles first formed uniting, and becoming the centres 

 of action toward which the other bubbles tend. But as the 

 larger bubbles do not continue to increase in size with the 

 arriving bubbles, the gas would seem to be only the vapor 

 of the expanded liquid. The bursting of these gaseous ac- 

 cumulations produces rents in the films, the spreading out of 

 which, the author believes, is due to the fact that the gase- 

 ous molecules, moving in all directions, force the liquid mole- 

 cules out horizontally in all directions, i. e., along the sur- 

 face. 



The previous researches of Mensbrugghe, of J. Thomson, 

 and especially of Tomlinson, had vastly extended our knowl- 

 edge of the action of the surface-tensions of various liquids 

 upon each other. But it appears that Cintolesi has reached 

 a new manifestation of the phenomena which, though doubt- 

 less always accompanying surface-tension, is independent of 

 it in many cases. 18 A, October 6 aiid 20, 1876, 85, 136. . 



METALLIC FILTRATION. 



Professor Lampadius, of Freiberg, concluding that at a cer- 

 tain low temperature of fusion the metallic impurities pres- 

 ent in the more easily fusible metals would separate, par- 

 tially as such, and partially as definite crystalline com- 



