68 Royal Society : — « 



Do some liquids, such as alcohol, act as nuclei by combining with a 

 portion of the water of the solution and liberating a little salt 

 which acts as a nucleus ? 



Exp. Supersaturated solutions of sodic sulphate were prepared, 

 in the manner described, in 2-oz. flasks, which were closed with a 

 plug of cotton-wool through which a bulb- 

 tube was passed, of the form figured *, con- 

 taining absolute alcohol. 



After waiting some time to be certain 

 that nuclei had not gained admittance, some 

 of the alcohol was run out on to the surface 

 of the solution by momentarily loosening the 

 stopper. 



This experiment was repeated many times, 

 at different temperatures and with alcohol of 

 various strengths ; but never did the alcohol 

 act as a nucleus. 



Previously to the experiment the alcohol 

 had been boiled to destroy nuclei. 



Exp. Concentrated sulphuric acid was 

 substituted for the alcohol, but likewise with 

 no result. The smallest quantity of acid was 

 added, so as to prevent any undue rise in 

 temperature, which would of course vitiate 

 the result. The flask was likewise kept 

 cold by a stream of water. 



In a later form of these experiments, a 

 small glass bulb with a long neck blown 

 from glass tubing, such as is used in the 

 elementary analysis of a fluid by com- 

 bustion, was made use of. 



The bulb was first well heated in a 

 Bunsen burner, so as to destroy any 

 nuclei which might adhere to it; then, 

 while still hot, the open end was dip- 

 ped intothe alcohol or acid under trial, 

 when, of course, as the air in the bulb 

 cooled some of the liquid was forced 

 up into it ; its liquid contents were 

 then boiled and the open end again 

 dipped into the fluid ; and as the va- 

 pour condensed, more fluid was forced 

 up into it. 



The tube was then surrounded by 

 cotton-wool and inserted into the neck 

 of the flask, and the supersaturated 

 solution boiled up for a moment, so 

 as to render the whole apparatus, 



* The loop was made in the tube at a so as to prevent any fluid from escaping 

 until required. 



