302 Dr. R. H. Brett and Mr. J. D. Smith's Experiments 



some portions of the contents glowed like a pyrophorns ; the 

 sulphate of lime had fused down, and had acted on the exte- 

 rior of the porcelain crucible; the contents consisted of a light 

 sooty spongy mass, very friable, and containing small glo- 

 bules of a metallic character, whilst the crucible itself was lined 

 with a black enamel, similar to the stain noticed in the former 

 experiments. Nine grains of this residue, from which the me- 

 tallic globules had been separated, were mixed with 30 grains 

 of nitrate of potash, and the same weight of carbonate of potash 

 prepared from the bicarbonate, and the mixture fused in a pla- 

 tinum crucible ; when cold, the fused mass, treated with water, 

 afforded a solution of a deep purple colour, exactly resem- 

 bling permanganate of potash ; by rapid filtration this solu- 

 tion was obtained clear ; decomposition appeared to be going 

 on during filtration, for the liquid whilst on the filter was in 

 a state of slight effervescence from the escape of a gas; by 

 exposure to atmospheric air this solution rapidly decomposed, 

 gradually losing its pink colour, becoming turbid, and finally 

 deposited a reddish brown powder, leaving a colourless solu- 

 tion ; this brown powder proved on examination to be per- 

 oxide of iron without a trace of manganese*. 



The colourless and alkaline solution, tested in the usual 

 way for silica, afforded a trace of this substance, which having 

 reason to believe resulted from impurity in the carbonate of 

 potash used in this experiment, it was tested for silica, and 

 found to contain apparently the same quantity as that obtained 

 from the alkaline solution just noticed ; in each case the quan- 

 tity was so minute as not to affect the most delicate balance, 

 though appreciable by the eye. The oxide of iron, separated 

 by filtration from the purple solution, and tested in the usual 

 way for silica, did not afford the slightest trace of this sub- 

 stance. 



The metallic globules before noticed were treated with hy- 

 drochloric and nitric acids; a black residue was obtained, which, 

 ignited, left a light brown ash soluble in hydrochloric acid. — 

 (J. D. S.) 



Two hundred grains of carbonate of potash, heated in an iron 

 tube to redness for three hours, and tested in the usual way 

 for silica, gave 0*3 grain of this substance ; when the quantity 



* I believe that this combination of oxide of iron with an alkali has be- 

 fore been noticed, but I cannot remember the authority, nor do I think any 

 investigation of the fact was attempted. It appears to me clearly to indi- 

 cate the existence of iron in a state of oxidation, doubtless higher than any 

 we are yet acquainted with, analogous to the acid oxides of manganese. I 

 shall pursue this investigation, and endeavour to isolate, or at least ascer- 

 tain the nature and composition of, this apparent ferric acid(?). — J. D. S. 



[See Journal de Pharmacie, torn, xxvii. p. 97. — Ed.] 



