540 Linhart — Hydrol i/sis of All;// Metallic Sulphates. 



cium and strontium esters, to their chlorides and the equiva- 

 lent amount of barium chloride to barium sulphate. (The 

 addition of barium chloride slightly retards the rate of hydrol- 

 ysis of the alkyl barium sulphates, as will be shown in a sub- 

 sequent paper on the hydrolysis of the alkyl sulphuric acids.) 



In the hydrolysis of the alkyl barium sulphates no attempt 

 was made to purify the precipitated barium sulphate-beyond 

 washing it with hot water until the wash water was free from 

 chlorine, since on ignition the small amount of included alkyl 

 sulphuric acid was destroyed and the included trace of alkyl 

 barium sulphate was changed to barium sulphate. In the 

 present work, however, the amount of barium chloride included 

 is too great to be neglected, and in order to remove this 

 included barium chloride the precipitated barium sulphate 

 resulting from the hydrolysis was filtered through an ignited 

 and weighed perforated platinum crucible fitted with an 

 asbestos mat, thoroughly washed with hot water, then gently 

 ignited until the mass completely charred. The solid cake 

 thus formed was broken up, care being taken not to disturb 

 the asbestos mat, and again ignited until all the carbon was 

 burned off and the barium sulphide, resulting from the reduc- 

 ing action of the carbon, oxidized to barium sulphate. f The 

 ignited and cooled precipitate was again washed with hot 

 water slightly acidulated with hydrochloric acid to remove any 

 basic chloride which might have been formed during the igni- 

 tion. The crucible was then gently ignited, cooled and 

 weighed. By this treatment practically all the barium chloride 

 was removed. 



Tlteory. — The calcium or strontium sulphate formed in this 

 reaction, being somewhat soluble in water, is instantaneously 

 and quantitatively removed from the reacting system by com- 

 bining with the barium chloride present to form barium sul- 

 phate. It is the weight of the barium sulphate which is given 

 in grams and gram equivalents in columns two and three in 

 Table I. 



The course of the reaction is similar to that of the alkyl 

 barium sulphates described in previous papers,;}; i. e., 



M(C 2 H & S0 4 ) 2 + HOH = MS0 4 + HC 2 H 6 S0 4 + C 2 H 6 OH. 



M = Ba, Sr or Ca. 



This leads to the mathematical expression 



* Some barium sulphide frequently escapes oxidation, but never more 

 than a small fraction of a per cent. 



f It is best to prevent caking by piercing the precipitate with a platinum 

 wire just as it begins to char. It then falls to a powder and the carbon and 

 barium sulphide are more easily oxidized. See this Journal, xxxiv, 290. 



\ Loc. cit. 



