the compounds of chromium. 223 
a splendent and metallic lustre, and a reddish-brown colour. 
They are tasteless, and insoluble in water. When digested 
in potash ley, chromic acid is separated, and oxide of silver 
remains. By this process I obtained from 2-95 grains of the 
crystals 
Chromic acid - - 1*27 or 13 - 2 atoms. 
Oxide of silver - - r68 or 17*19 if atom. 
I consider the salt as a bichromate composed of 
2 atoms chromic acid - 13 
1 atom oxide of silver - 14*75 
27-75 
The small excess of silver in the analysis was probably 
owing to the digestion in the potash ley not having been con- 
tinued long enough. The scale was rather too small to 
entitle me to expect very accurate results. 
4. Potash-chromate of Soda. 
This compound salt is easily formed by adding carbonate 
of soda to a solution of bichromate of potash in the atomic 
proportions. The carbonate of soda dissolves with effer- 
vescence, and the solution has the yellow colour of neutra 
chromate of potash. When the liquid is evaporated, crystals 
of the compound salt are deposited. These crystals have a 
yellow colour, and are four sided oblique prisms, but so 
irregular, that it was very difficult to make out the shape. 
When heated, they decrepitated and became red ; but reco- 
vered their colour on cooling. 23*57 grains by exposure to 
a red heat lost 0*57 grain of their weight. Hence the con- 
stituents of the salt are 
