H. L. Wells — Caesium- Cuprous Chlorides. 97 



Found. Calculated for 



I. II. III. 3CsCl . Cu 2 Clo. 



Ccesium 56-81 56-66 5684 56-72 



Copper 17-95 17*89 17"84 18-05 



Chlorine 25-03 25-08 25-13 2o'23 



It is evident that this salt has the formula Cs 3 Cu 2 Cl 6 . 



"With nearly or quite saturated caesium chloride solutions 

 containing comparatively little cuprous chloride, prismatic 

 crystals are formed on cooling. The crystals are very pale 

 yellow in color and their luster is less brilliant than' that of the 

 preceding compound. Crystals having a diameter of two or 

 three millimeters and a length of several centimeters were 

 sometimes observed. This salt forms under very narrow limits 

 of conditions and it is very difficult to obtain it free from the 

 preceding salt, and especially from caesium chloride which 

 usually crystallizes with it when the conditions are right for 

 its formation. After a great many trials three crops which 

 were satisfactory were obtained for analysis. The third anal- 

 ysis represents crystals which were picked out of a solution 

 one at a time and. separately pressed between smooth filter- 

 papers. All the preparations were carefully examined under 

 the microscope and were evidently pure. 



Calculated for 

 Pound. 6CsCl . Cu 2 Cl 2 . 2H,0. 



Caesium 64*77 65-07 64-09 64-10 



Copper 9-38 9'42 10-04 10 20 



Chlorine 22-70 22-83 22-81 



Water (difference) 3-15 «'69 3-14 2-89 



The analyses show that the salt has the formula Cs 3 Cu 

 Cl 4 . H 2 0. 



The previously described cuprous double halogen salts, with 

 the new caesium salts for comparison, are given below : 



Caesium Salts. Previous Salts. 



CsCl . Cu 9 Cl 9 4NH 4 C1 . 3Cu„CI 2 



3CsCl . Cu 2 CC 2NH 4 I . Cu 2 I 2 . H o 



6CsCl . Ca.Cl,. 2H„0 4KC1 . Cu,Cl 



4NH 4 C1 . Cu 2 Cl 3 



It is remarkable that there is no correspondence in type be- 

 tween the caesium compounds and the others, and that such a 

 variety of types appears to exist. The formula 4NH 4 C1 . 

 3Cu 2 Cl 2 may be considered, somewhat doubtful on account of 

 its complex ratio, and because with one-fourth less ammonium 

 chloride it would correspond to the first caesium salt. 



The salt Cs 3 Cu 2 Cl s is noticeable on account of its rather com- 

 plex formula and because it has the same ratio of caesium to 



Am. Jour. Sci — Third Series, Vol. XLVII, No. 278.— Feb., 1894 



7 



