106 McClenahan — Hydrous Thallic Chloride. 



H H 



H H / 



6 _ 6 _ ci 



Ba )rr Mg tt tt Al O— O— CI 



\rji — (K* 1 ' \ ti M > \ ii 



X ° °\H X i_(i_ cl _ /H \ 11 H 



V V \H V H H 



H H X 6_6-C1 



A ii 



in which the molecules of water which may be expelled easily 

 by heat without loss of hydrogen chloride, and at the same 

 rate in air and in hydrogen chloride, are placed outside the 

 chlorine of complex, while those molecules of water which are 

 removed with more difficulty and at a rate affected by the . 

 environment, air or hydrogen chloride, are placed inside the 

 chlorine. The suggestion was made that the influence of 

 hydrogen chloride as compared with that of air upon mole- 

 cules outside the complex is insignificant, while upon mole- 

 cules of water within the complex the effect may appear 

 variably, according *to conditions, (1) in a retardation of dehy- 

 dration and greater stability of the whole complex, or (2) in 

 acceleration of dehydration with formation of the anhydrous 

 chloride or with hydrolysis implying loss of hydrogen chloride 

 and formation of a residual hydroxide or oxide. 



In the present paper, the changes which the thallium chlo- 

 ride T1C1 8 * 4H 2 undergoes when heated in air and in hydro- 

 gen chloride have been studied and discussed in relation to the 

 hypothesis of quadrivalent oxygen. 



Experimental Part. 



Thallous nitrate was dissolved in distilled water and the 

 thallium precipitated as the chloride by means of hydrochloric 

 acid. The precipitate was filtered on asbestos and washed 

 thoroughly of all hydrochloric acid. It was then transferred 

 to a test tube and chlorinated until the last traces of the solid 

 were gone. The solution was evaporated to incipient crystal- 

 lization and allowed to stand until the clear crystals of thallic 

 chloride appeared. These were removed, dried by means of 

 filter papers, desiccated for a brief period and a sample taken 

 for analysis. 



The chlorine in the salt was estimated by the usual silver 

 chloride method, making sure of enough nitric acid. The 

 thallium was estimated as thallous sulphate.* A weighed por- 



* Browning : this Journal, ix, 137 (1900). 



