4o. Ona New Series of the Double Sulphates of Barium 
with the Sulphates of the Substituted Ammonium 
Bases. Part I. 
By Rastk Lat Darra and Haripas SEN. 
Barium sulphate is always held to be a most refractory 
and insoluble substance, and it has thus not as ye n 
found to combine with any other salts. It does not decompose 
even in the presence of strong acids. It is for this reason that 
in the analysis of sulphates in inorganic as well as organic 
substances the radicle SO, is estimated in this form. 
estimating the total sulphate in the sulphates of the substi- 
tuted ammonium bases, however, it was found that the pre- 
why such compounds have hitherto escaped isolation. The re- 
action evidently takes place according to the following equa- 
tion, M representing mono-acid bases. 
n.M,H,SO, +n.BaCl, = 2nM,HCl + n.BaSO, 
n.BaSO, + M,H,SO, =M,H,S0,, n.BaSO,. 
Summing up the two equations 
(n +1)M,H,SO, } n.BaCl, = M,H,SO,.nBaSO, + 2nM.HC!. 
1. Pyridine Barium Sulphate. 
(C,H,N),H,SO,.2BaSO,,. 
5 e.c. of a strong solution of barium chloride was gradu- 
ally added to 30 e.c. of a concentrated solution of exactly neu- 
