324 MR C. G. WILLIAMS ON THE VOLATILE BASES 



Bichromate of Lepidine. — This extremely beautiful salt is easily obtained by 

 adding an excess of a rather dilute solution of chromic acid to lepidine. For the 

 first few seconds the chromate, on touching with a glass-rod, appears resinous, 

 but the instant it is stirred the salt becomes gritty and crystalline. On filtering 

 off the crystalline powder obtained in this manner, and dissolving it in hot water, 

 the salt crystallizes out on cooling, in needles nearly an inch long, extremely 

 brilliant, and of a rich golden yellow. The mother liquors, on evaporation, yield 

 a fresh crop. It does not appear to be at all decomposed by moderate boiling 

 with excess of dilute chromic acid. It decomposes at no very elevated tempera- 

 ture, and if suddenly heated to 212° when slightly damp, it becomes converted into 

 a mixture of green oxide of chromium and charcoal. On one occasion, this took 

 place with a very curious phenomenon. About four grains in powder having been 

 placed on a water-glass, on the upper shelf of the water-bath, it was not observed 

 for about one hour, during which time it had become converted into a mass of 

 flattened rods, reaching to the top of the water-bath, a distance of about 1\ inches, 

 and had turned down again on all sides, in a manner which gave the whole much 

 the appearance of the capital of a Corinthian column. In general, however, it 

 may be dried at 212° with perfect safety; if retained more than an hour or two in 

 the bath it begins to turn slightly brown, but experiences no further change during 

 five hours' exposure. On ignition, the salt behaves like the bichromate of ammonia 

 and the chromate of strychnine, inasmuch as it leaves pure green oxide of chro- 

 mium. This fact enables the constitution of the salt to be determined with accu- 

 racy. The following experiments were made upon three different specimens. 



f 4-105 grains of bichromate lepidine, dried at 212°, gave 

 \ 1-260 ... green oxide of chromium. 



f 6290 grains of bichromate lepidine, dried at 212° until slightly brown, gave 

 1940 ... green oxide of chromium. 



„,( 



6-850 grains of bichromate lepidine, dried at 212° for five hours, ga\e 

 2-120 ... green oxide of chromium. 



7'315 grains of bichromate lepidine gave 



IV. { 12-620 





carbonic acid, and 









( 2-560 





water. 

















Experiment. 







Calculation. 







I. 



II. 



ill. 



IV. 



"~~ 







Carbon, 





. . . 





47-05 



47-36 



C 20 



1200 



Hydrogen, . 









3-89 



3-95 



H 10 



10-0 



Nitrogen, 





. . . 







5-52 



N 



14-0 



Chromium, . 



21-17 



21-28 



21-35 





21-07 



Cr 2 



53-4 



Oxygen, 











22-10 



o 7 



560 



100-00 253-4 



Consequently the formula, is 



C 20 H 9 N + 2 Cr 3 + HO. 



The salt analysed agrees therefore with the bichromate of ammonia in only con- 



taining one atom of water. 



