410 Dr. Thoinas Thomson on the 



Tested by the blow-pipe, it fused with effervescence, with 

 carbonate of soda forming a very white opaque bead. With 

 borax and bi-phosphate of soda, it fused into transparent 

 beads, the latter of which, had a very slight tint of yellow. 

 From these phenomena, I considered it as columbic acid 

 very slightly contaminated with iron. It was evidently not 

 tungstic acid, in order to discover which, I had been induced 

 to digest the columbic acid in ammonia.''^ 



I was not aware before that columbic acid is soluble in 

 ammonia; but verified the fact by subsequent trials. The 

 quantity dissolved, however, is always very small ; and after 

 ignition columbic acid becomes quite insoluble in ammonia. 



5. The residual columbic acid being ignited, weighed 

 15*24 grains. AVhile red hot, it had a distinct tint of 

 yellow, and when allowed to codl it retained a perceptible 

 brownish tinge. It was therefore, mixed with six times 

 its weight of anhydrous carbonate of soda aud fused. 



The fused mass, when coldj had a light green colour 

 shewing the presence of manganese. It was softened with 

 water, digested in muriatic acid, and the whole thrown on 

 a filter to collect the columbic acid ; which was thoroughly 

 washed with boiling water, dried and ignited. It weighed 

 after ignition 14*69 grains. Thus, making the whole 

 columbic acid 14*78 grains (adding what had been dissolved 

 in ammonia). It was beautifully white, and apparently 

 pure. 



The muriatic solution, containing the soda and impurity 

 from the columbic acid, was boiled with an excess of car- 

 bonate of soda in a flask. A dark brown matter fell, 

 which being edulcorated, dried, and ignited, weighed 0*55 

 grain, and was red oxide of manganese. 



6. The muriatic acid solution (paragraph 3) was as nearly 

 neutralized as possible, and then mixed and digested with 

 benzoate of ammonia. The iron was thrown down in the 

 state of benzoated peroxide. After ignition, it weighed 

 3*48 grains = 3*13 grains protoxide of iron. 



7. The liquid thus freed from iron was mixed with an 

 excess of carbonate of soda and boiled. The precipitate 

 that fell, after edulcoration and ignition, was red oxide of 

 manganese, and weighed 1*23 grains: making, with the 



* Tungstic acid liad been discovered by Ekeberg in lantalitc, and hii discovery 

 had been confirmed by Berzelius. 



