172 
If, for the sake of brevity, we call Ba Cl2.2H20 = Bag and Cu Clo. 
2H20 = Cuz, the reaction is then: 
Baz + Cue — D{22 = Din + Solution 
r Bag + Cug + Di, + Sol. 
Bag — Cuz — Die + Sol. Bag + Dyo2o+ Dy, + Sol. 
Bag + Cuz + Di22+ Dit | a | 
Cuz + Di22 + Di1 + Sol, 
Hence, of the invariant (P) equilibrium two monovariant (P) 
proceed to lower and three to higher temperatures, or if we only 
consider the systems in which a solution occurs, one to lower and 
three to higher temperatures. 
The system proceeding to lower temperatures: Bag + Cue + 
Di22+ sol. still exists at 40° and is represented in fig. 1 by the 
point h. The system proceeding to higher temperatures: Cuz + Di22 
+ Dj + solution terminates at 57°, when tbe solution only still 
contains the three components CuCle , KCI and water. 
The other two systems proceeding to higher temperatures still 
exist at 60°; the solution of the system Bag + Cuz + Dit + solution 
is represented in fig. 2 by the point / and that of the system: 
BaCle + Di22-+ Di is indicated in fig. 2 by the point h. 
Chemistry. — “The system HgCl,—CuCl,—H,0.” By Prof. F. 
A. H. ScHREINEMAKERS and J. C. THonvs. 
(Communicated in the meeting of September 28, 1912). 
In order to ascertain whether or not the salts HgCl, and CuCl, 
form a double salt, the isotherm of 35° was determined; the result 
of this investigation is that, at 35° no double salt was found but 
that the salts HgCl, and CuCl,.2H,O can exist by the side of 
each other. 
In fig. 1, the experimentally 
determined isotherm of 35° is 
represented schematically; the 
apexes W, HzCl, and CuCl, repre- 
sent the three components, and 
the point Cu, the hydrate CuCl, . 
ue SEO. 
The isotherm consists of the 
two branches ac and dc; ac indi- 
cates the solutions which are 
saturated with the hydrate CuCl, . 
2H,O, bc those saturated with 
Wig, a. 
