McClenahan — Hydrous Thallic Chloride. 105 



accompanied by chlorine, but that evidence for a definite 

 monohydrate stage is slight. Cushman proposes to account 

 for the relations of water of crystallization in salt complexes 

 upon the hypothesis that oxygen can be quadrivalent and for 

 the tetrahydrated thallic chloride suggests the symbol 



H /C1=0 / H 



H \f> — CI— (*> — TV \ H 



H/ I \C1=0<« 



and for the crystalline compound obtained by Meyer when the 

 preparation of the hydrous thallic chloride is attempted in 

 presence of hydrochloric acid the related symbol 



, /Cl= 0< R 



H— C1=C1 — O— TV >£ 



k \ci=o/g 



For the molecule of hydrous aluminium chloride Ctishman 

 suggests that the water is held within the complex in a manner 

 suggested by the symbol 



/ 



Al 



H 



H 





i 

 0- 



H 



i 

 -0 - 



i 

 H 



H 



-CI 



i 

 - 0- 



i 

 -0- 



-CI 



i 

 H 



H 



H 





\ i 

 0- 



i 

 -0- 



-CI 



i 

 H 



i 

 H 





which brings out the observed fact that water cannot be broken 

 from the molecule without formation of hydrogen chloride, at 

 least in the primary action. The application of Cushman's 

 hypothesis of the quadrivalent linking of oxygen in hydrous 

 salts has been made in a former paper from this laboratory* 

 to the comparative phenomena observed when certain typical 

 hydrous salts, BaCl 2 ■ 2H 2 3 MgCl 2 ■ 6H 2 0, and A1C1, ■ 6H 2 

 are dehydrated in air and in an atmosphere of hydrogen chlo- 

 ride. It was shown that the phenomena of these salts are in 

 harmony with the assumption of the symbols 



* Gooch and McClenahan : this Journal, xvii, 865 (1904). 



