Bubbles of Gas and of Vapour in Liquids. 205 



I am not aware whether Herr Schroder has seen my subse- 

 qnent papers on the subject of which he treats* ; but as he uses 

 the same authorities, and no other, it is probable that he has. 

 It cost me a considerable amount of research to find out the 

 various memoirs of Oersted, Schonbein, Liebig, and Gernez on 

 the liberation of gases from solution under the influence of nu- 

 clei — of Watt and Southern, Achard, Gay-Lussac, Budberg, 

 Marcet, Bostock, Magnus, Donny, Grove, and Dufour on the 

 phenomena of boiling liquids ; and yet all these authorities, and 

 no other, are made use of by Herr Schroder. 



It is equally remarkable that Herr Schroder should use the 

 terms ce clean" and " unclean" in precisely the same sense that 

 I do, in distinguishing between a body that is ' ' inactive " in 

 liberating gas or vapour from liquids and one that is " active" 

 in doing so — and that he should describe an inactive body as 

 being made active by drawing it through the "finger and thumb" 

 (I say "the hand"), when it becomes contaminated with greasy 

 or fatty matter which renders it active. It is also remarkable 

 that Herr Schroder should have hit upon the same explanation 

 of the action of flame, sulphuric acid, alkaline solutions, alcohol, 

 &c. in rendering dirty bodies chemically clean, and therefore in- 

 active as nuclei in gaseous and vaporous solutions. 



I should have been quite content to leave all these matters 

 unnoticed, seeing that priority of publication is in my favour, 

 were it not that Herr Schroder claims for his distinguished coun- 

 tryman Schonbein the merit of first distinguishing in 1837 be- 

 tween an " inactive " and an " unclean " body in liberating gas. 



Now in Schonbeur's short paper f there is not the slightest 

 evidence that the author had any idea whatever of the difference 

 between clean and unclean bodies in liberating gas from solution. 

 His theory was that solids acted by carrying down air, into which 

 the gas in solution expanded and so got liberated. He expressly 

 says that metals from whose surface the adhering film of air has 

 been removed by dipping them into boiling water, do not disen- 

 gage bubbles of steam from boiling liquids. Herr Schroder also 

 makes Schonbein refer to the action of porous bodies as nuclei, 

 whereas Schonbein does not even mention permanently porous 

 bodies, such as charcoal, pumice, &c. He states, as Bostock 

 had done twelve years before, that bits of wood are particularly 



* " On "some Effects of a Chemically Clean Surface," Phil. Mag. for 

 October 1868. 



" On the Action of Solid Nuclei in liberating Vapour from Boiling Li- 

 quids," Proceedings of the Royal Society for January 1869. 



" Historical Notes on some Phenomena connected with the Boiling of 

 Liquids," Phil. Mag. for March 1869. 



"On Catharism, or the Influence of Chemically Clean Surfaces," Jour- 

 nal of the Chemical Society for April 1869. 



t Pogg. Ann, vol. xl. p. 391. 



