210 
Dr. Thomson on some of 
The result of the analysis was 
Carbonic acid - - 2-75 
Green oxide - - 26*44 
Water - 23*69 
In this analysis, as in the preceding, there is a slight excess 
both of oxide and water ; I ascribe this to the same cause. 
Such analyses can scarcely be made with very great accuracy. 
Thus I obtained a penta-carbonate instead of a neutral 
carbonate, when I employed bicarbonate of potash as a pre- 
cipitant ; a result quite unexpected, and not easily ex- 
plained. 
I tried to form a neutral carbonate by passing a current of 
carbonic acid through newly precipitated dicarbonate, still 
suspended in water ; but the process did not answer. 
5. Phosphate of chromium. 
Phosphate of soda precipitates exceedingly dilute solutions 
of muriate of chromium. The precipitate while in the liquid 
state has a dirty whitish green colour. But when phosphate of 
chromium is in the state of a dry powder, it has a very fine 
deep but lively green colour. It is quite tasteless, and inso- 
luble in water. To determine the composition of this salt, 
16 grains of anhydrous phosphate of soda (containing 7*46 
grains of acid) were dissolved in water and mixed with an 
excess of muriate of chromium, previously rendered as 
neutral as possible by evaporation to dryness. The mixed 
liquids were placed on the sand bath, in a porcelain dish, and 
evaporated to dryness. Water was digested over the dry 
residue till it ceased to dissolve any more. The insoluble 
