11 



On analysis it yielded, as the mean of four determinations 

 made on different preparations, 



CI 21-06 



Cr 48-91 



numbers approximating to those obtained by Hr. Zettnow. 

 To this compound I was induced, for reasons which I need 

 not here reproduce, to give the formula 



ClCrOa. 0. CrO. Cr.O.Cl. 

 and to regard it as the chromium term of a series of salts a 

 few members of which had already been described by 

 Peligot, viz. — 



Potassium chloro-chromate ClCrOi. 0. Ko- ^- CrOgCl 



Sodium do. ClCrOa. 0. Na^. 0. CrO.Cl 



Ammonium do. CiCrO,. 0. (NH,),. 0. CrO^Cl 



Magnesium do. CiCrO,. 0. Mg. 0. CrOoCl 



Calcium do. ClCiOo. 0. Ca. 0. CrO^Cl, 



The above formula for the chromium chloro-chromate 

 requires 



CI 21-86 



Cr 48-54 



From the close agreement in the analytical results and 

 correspondence in their physical properties, I am inclined to 

 believe that Hr. Zettnow's compound is identical with mine. 

 Potassium chloro-chromate heated with sulphuric acid yields, 

 among other products, chromyl dichloride, and, doubtless 

 Hr. Zettnow's compound has been derived from this body 

 under circumstances analogous to those in which I have 

 already operated. As my little notice on this matter has 

 evidently not come under Hr. Zettnow's observation, he 

 may be interested to learn that the six or seven weeks' 

 time which he finds necessary to give to the preparation of 

 this rather uninteresting compound may be considerably 

 shortened by simply heating the chromyl dichloride in a 

 closed vessel, when in a few minutes any wished-for quantity 

 may be transformed almost completely into the chromium 

 chloro-chromate and free chlorine. 



