1889.] On Salts of a Base containing Chromium and Urea. 338 



oxalate, there was slowly deposited during several days a quantity of 

 very dark-green, almost black, crystals with exceedingly bright faces. 

 The crystals on examination were, however, found to be a double 

 oxalate of the base with chromium oxalate, having the formula 



They are very sparingly soluble in cold, more readily in hot water, 

 and insoluble in the usual organic solvents. v 

 The following results were obtained on analysis : 



1. 0-4217 gram gave 0-0187 gram H 2 0. 



2. 0-4217 on ignition 0'0818 gram O 2 3 . 



3. 0-14165 on combustion 25'06 c.c. N" and 48'27 c.c. CO 2 

 at C. and 760 mm. 



This substance crystallises in the rhombic system, and has a well- 

 marked hemihedrism with inclined faces. The crystals consist of 

 well-developed prisms with a large deeply striated brachypinakoid, 

 terminated sometimes by six planes, sometimes by four equally 

 developed planes, and sometimes by two prominent planes of K (111), 

 with other minor planes. The form (210) is also present, but the 

 planes of this form are dull and deeply striated. The prism planes 

 are also sometimes considerably striated, but the striations on m and 

 raj on the same crystal or on the parallel faces do not as a rule cor- 

 respond. The development of the crystals is to a certain extent 

 shown by the accompanying diagrams, figs. 1 and 2, which repre- 

 sent some of the crystals measured by me. The prism in fig. 2 is 

 placed horizontally for showing the hemi-pyramids more distinctly. 



z 2 



