Linhart — Hydrolysis of Metallic Alkyl Sulphates. 289 



Art. XXVIII. — On the Hydrolysis of Metallic Alkyl Sul- 

 phates ; by G. A. Linhart. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — ccxxxiv.] 

 II. Methyl and Propyl Barium Sulphates. 



In a previous article* it was shown both theoretically and 

 experimentally that the rate of decomposition of ethyl barium 

 sulphate in dilute hydrochloric acid solution is perfectly 

 normal, and that it is approximately proportional to the 

 strength of the catalyzer used. The purpose of this paper is 

 to show the influence on the rate of decomposition of the salt 

 of substituting a methyl or propyl group for the ethyl group. 

 It was anticipated that the rate of decomposition would 

 decrease with the increase in the molecular weight of the 

 alkyl group, and this was confirmed by experiment, as is 

 shown in Table II. 



Preparation and Analysis of the Salts. — The salts were 

 prepared as described in the first paper, f except that mechan- 

 ical stirring was used during the preparation of the methyl 

 and propyl sulphuric acids, as well as in their neutralization 

 with barium carbonate ; in the first case to prevent charring, 

 in the second, to hasten the neutralization, as well as to pre- 

 vent overflowing. A large crystallizing dish was used for the 

 purpose. 



The propyl salt thus prepared contains varying amounts of 

 water of crystallization (one crop of crystals contained one 

 molecule of water, another contained only one-half molecule 

 of water) while the methyl salt thus prepared proved to be 

 anhydrous. In fact all three salts, methyl-, ethyl-, and propyl 

 barium sulphate, tend to lose their water of crystallization on 

 standing. In one case the mother liquor from the methyl 

 barium sulphate was allowed to stand over night, and on the 

 next day it was found that the salt had crystallized in large 

 rectangular plates (1 X 2 X '2 centimeters). All three salts may, 

 however, be prepared with definite amounts of water of crys- 

 tallization by allowing the crystals to remain in a Biichner 

 funnel which is connected with the aspirator for several hours 

 until the salt is fairly dry. It is then spread out on filter 

 paper and kept in a dry place for a few hours. The salts thus 

 prepared correspond to the formulae: 



Ba(CH 3 S0 4 ) 2 .2H 2 0, Ba(C 2 H 6 S0 4 ) 2 .2H 2 0, Ba(C 3 H 7 S0 4 ) 2 ,H 2 0. 



Method of Hydrolysis. — The hydrolyses were made as 

 described in the first paper.:}: Attention has been called to 

 the fact that the precipitated barium sulphate chars on igni- 



* This Journal, xxxii, 53. f Loc. cit. % Loe. cit. 



