970 



The anhj'dride formed Ccaii be obtained by distillation, sodium 

 pyrosnlphate being left behind in the first case and sodium sulphate 

 in the second case. The so obtained sodium p}'rosulj)hate is very 

 voluminous and on distillation with acetic acid and sodium acetate 

 it again produces acetic anhydride. In this case refrigeration is not 

 necessary when adding together the three components. If, however, 

 the above pyrosnlphate is first submitted to fusion a considerable 

 decrease in volume takes place and it is then no longer capable 

 of forming acetic anhydride, resembling in this respect a pyrosnlphate 

 prepared in the usual manner. 



In the action of sodium chloride on acetylsulphuric acid acetyl 

 chloride is formed. In a manner analogous to thai of the preparation 

 of acetylsulphuric acid from acetic acid and SO» , were prepared 

 butyrylsulphuric acid and benzoylsid])huric acid, from which were 

 obtained in a corres|)Oudin": maniu'i" butyric- and benzoic anhydride, 

 respectively. 



Chemistry. — "Comir.rirm Itetwcm the ndsorptioii-UotJieriii and the 

 hi/rs of Proust and Henhv." IJy Dr. W. P. A. Jonkkr. (Com- 

 municated by Prof. SCHREINEMAKERS). 



(Communicated in the meeting of February 28, 1914). 



1. The adsorption-isotherm is of great importance for the study 

 of the colloids. Fi'om various sides efforts have been made <o (iud 

 a connexion between this law and other laws of physical chemistry. 

 Starting from the phase rule and the law of mass action which 

 both can be deduced from the two main laws of thertnody- 

 uamics, I have tried, in the subjoined lines, to trace the comiexion 

 between the adsorption-isotherm, (he division ride and the law of 

 constant proportions. 



The question whethei- the phase rule may be ap|)lied unreservedly 

 to dis|)ersive systems will not be discussed here. 



2. Let us imagine three substances A, B, and C. A and C form 

 two non-mixable phases. C we may call the solvent (^dispersive me- 

 dium). /> is soluble in 6' and can give a "compound" with yl. (What 

 kind of compound this is does not mattei-; it may be a chemical 

 compound or an adsorption coni|)Ound, or an ordinary solution). 



When the equilibrium has set in we have F=n^2 — r; when 

 ?i nr 3, r = 2 and p and 7' are constant, i'^= 1, therefore, the system 

 is monovariant (p-Tj. Which variables can occur here? 



A and C form two phases between which B can distribute itself. 



