1873.] Mr. W. N. Hartley on a new Chromic Oxalate. 501 



i. n. in. iv. 



grin. grm. grm. grin. 



Weight of salt taken . . 1-953 1-78 1-34 1-00 



Found. 



CaC0 3 0-4163 0-3797 0-2842 



Cr 2 3 0-3062 0-2823 0*1942 



K 0-08* 



Percentage composition. 



I. II. III. IV. 



Ca 8-52 8-53 8-48 



Cr 2 3 15-67 15-85 15-13 16-38 



H 2 16-0 16-1 16-0 — - 



K 8-00 



Formula of salt K Ca" ) on ^ A ^ 



Found. 



Calculated. I. II. III. 



Ga = 8-56 8-48 8-52 8-53 



K = 8-35 8-00 



Cr = 11-13 11-15 10-57 10-63 



H 2 = 15-41 16-00 16-00 16-10 



Solubility. — 1 part of the salt dissolved in about 22 of water at 16° C, 

 and in 5 parts at 100° C. 



It may be noticed that the water found is a little above the calculated 

 amount, just so much in fact as the chromium is too low ; this is not to 

 be wondered at when the singular nature of the salt is taken into account, 

 a salt which at the ordinary atmospheric pressure and temperature loses 

 4 per cent., or 1 molecule of water in dry air — a substance that can be 

 dried only by crushing between bibulous paper and exposure in an open 

 place to cool air. The solution, of a greenish-purple colour, when boiled 

 becomes more decidedly green, and assumes its original colour on cooling. 

 A little calcium oxalate generally separates out during recrystallization, 

 The salt is exceedingly stable, and it crystallizes with the greatest ease 

 from hot or cold, acid or neutral solutions, and can be precipitated in 

 the crystalline state. It is almost insoluble in strong hydrochloric acid. 



The following are the properties of the crystals : — When deposited 

 slowly they are formed in clusters, the individual crystals being never 

 more than of an inch in thickness and \ an inch long. They 

 possess a greenish-black lustre, and apparently consist of prisms with a 

 rectangular base ; they reflect white light. From hot solutions much 

 smaller crystals deposit ; their colour is olive-green in daylight, and 



* Calculated from 0424 grm. of platinum. 



