F. R. Fraprle — Chromates of Ccesium. 



313 



this kind were obtained at Cambridge, from lack of time. On 

 resuming the work at Munich in the fall of 1902, using 

 another preparation of caesium, only the orthorhombic crystals 

 were obtained. The caesium chromate used, obtained from 

 Merck, was recrystallized twice as dichloriodide, and then con- 

 verted into chromate as before. The orthorhombic crystals 

 were analysed and found to be of the same composition as 



hexagonal ones, as follows ; 



Barium 

 Salt taken. chromate. 



£0rO 3 , 



found. 



Calculated. 



0-3960 g. 0-2614 g. 



26-12 



2622 



Many attempts were now made to prepare the hexagonal 

 crystals again, but absolutely in vain. Crystallization from either 

 hot or cold solutions, quickly or slowly, always gave the same 

 result, orthorhombic crystals. Only a small quantity of the 

 formerly obtained hexagonal crystals was available, and repeated 

 inoculations of solutions saturated and supersaturated with the 

 orthorhombic salt had always the same result ; the hexagonal 

 crystals dissolved, and orthorhombic ones crystallized out. 

 As the method of preparation in both places was the same, 

 and the greatest care was taken in the purification of all ma- 

 terials used, and as the composition of the two salts is the same, 

 it must be assumed that the hexagonal form is labile at ordin- 

 ary temperature and pressure, and cannot exist in the presence 

 of the orthorhombic form, although it may be possible to pre- 

 pare it when no orthorhombic salt is present to start crystalliza- 

 tion. 



The measurements of the orthorhombic salt follow : 

 Cs 2 Cr0 4 /3 (Orthorhombic). 

 Axial ratio : 0-5640 : 1 : 0-7577. 















Calcu- 



Dif- 



Faces. 



Symbols. 



No. 



Mean. 





Limits. 



lated. 



ference 



bp 



010 110 



50 



*60°35' 



60 c 



> 24-60° 51' 









ap 



100 110 



4 



29 25 



29 



21-29 29 



29 c 



'25' 



±0' 



pp 



110 110 



13 



58 50 



58 



36-58 57 



58 



50 



±0 



bq 



010 Oil 



46 



*52 51 



52 



26-53 15 









Cq 



001 011 



17 



37 9 



36 



54-37 25 



37 



9 



±0 



qq' 



011 021 



10 



19 23 



19 



6-19 35 



19 



16 



+ 7 



bq' 



010 021 



9 



33 33 



33 



22 -33 42 



33 



25 



+ 8 



ao 



100 111 



10 



43 7 



43 



2-43 14 



43 



2 



+ 5 



oq 



111 011 



12 



46 53 



46 



46 -47 3 



46 



58 



— 5 



op 



HI 110 



26 



33 3 



32 



55-33 12 



32 



57 



+ 6 



CO 



001 in 



10 



56 57 



56 



48-57 13 



57 



3 



— 6 



bo 



010 111 

 010 130 



3 



65 41 



65 



37-65 56 



65 

 30 



40 

 35 



4-1 



Cleavage not 



observed. 













Forms": a (100), b 



(010), G 



(ooi; 



),o\lll),p 



(110), 



(OH), t 



(021). 



















