NATURE OF THE PROCESS 15 



On the other hand, it cannot be well assumed that salt or sugar 

 furthers the formation of soap in the oil-drops.^ 



If my view as to the formation of froth in oil-drops is 

 correct, this process belongs to the category of phenomena 

 which Berthold, and after him Fr. Schwarz, have termed pro- 

 cesses of desolution? They understand by this the separa- 

 tion from one body of another dissolved in it under certain 

 conditions which remove or diminish the solubility of the 

 latter. Schwarz gives various methods of producing such 

 processes of desolution artificially, whereby the originally- 

 dissolved body, after being separated out from the so-called 

 " homogeneous mixture," appears in the form of drops or 

 vacuoles. Mastix or resin in weak alcohol, as well as the 

 precipitation membrane produced from soluble glue (Traube's 

 /8-glue) by a solution of tannin, are said to show these 

 vacuoles. For the resins mentioned, the phenomenon is 

 explained by the fact that they formed a homogeneous 

 mixture of two bodies, of which one is soluble in alcohol, 

 the other not; the precipitation membrane produced 

 from yS-glue consists of a modification which is soluble, and 

 another insoluble, in H^O, and hence gradually exhibits 

 a process of desolution under the influence of water. It 

 is of interest that this process of desolution leads, in the 

 glue membrane, to the formation of frothy honeycomb-like 

 structures (so-called reticular structures), although here the 

 ground substance of the membrane certainly does not possess 

 a really fluid consistency. Finally Schwarz brings in the 

 " separating out of the fluid droplets of soap, which arise if 

 oil containing oleic acid is brought into a watery solution of 

 potassium carbonate, or disodic phosphate, or in weak am- 



1 I cannot, however, refrain from referring to a circumstance which does 

 not harmonise well with the explanation attempted, namely, the fact that 

 even in drops of chemically pm-e oleic acid which were placed in water, 

 minute droplets appear after a little while, although not so plentifully as in 

 usual olive oil. If the oleic acid had stood twenty-four hours over pulverised 

 white of egg, the formation of droplets in water was considerably more 

 energetic and rapid, so that the deeper region of the drop became quite 

 turbid. 



' For this term see the Translator's Preface. 



