448 CHEMISTRY. 



ductions of the authors, or to discuss the comprehensive questions 

 which the work illustrates, from imperfect and unclassified materials. 

 Meanwhile we may record our conviction, that for beauty of typo- 

 graphy, and artistic skill and minute accuracy of illustration, we can 

 scarcely couceive the work surpassed. When completed it will form 

 a mine of information to be worked by many a succeeding laborer, 

 and must be considered as an indispensable addition to every public 



and scientific library. 



D. W. 



SCIENTIFIC AND LITERARY NOTES. 



CHEMISTRY. 



FLUOKINE. 



Nickles is of opinion that the usual test for fluorine is not s'/> reliable as has been 

 supposed. Sulphuric acid, however carefully purified, often contains traces of 

 hydrofluoric acid, and also from the fact that the vapours of any acid, or even of 

 water at a rather elevated temperature, are capable of acting upon glass so as to 

 produce an engraving similar to that obtained by hydrofluoric acid, additional 

 grounds for doubt exist. He recommends the substitution of plates of rock 

 crystal for those of glass, that substance being acted on only by hydrofluoric acid. 



ALUMINA. 



G-audin has obtained hard, brilliant and clear crystals of alumina by introducing 

 into a crucible, luted with lamp-black, equal parts of common alum and bisulphate 

 of potassa, previously calcined and reduced to powder. The crucible is submitted 

 to the violent heat of a blast furnace for a quarter of an hour. On breaking the 

 crucible we find, in the hollow of the luting, a concretion bristling with brilliant 

 points. The alumina is separated by dilute nitromuriatic acid. 



TANTALUM. 



Rose has obtained a nituret of tantalum, and has described the processes for 

 obtaining tantalic acid, perfectly pure, by fusion with the bisulphate of potassa or 

 ammonia. The acid dissolves in the latter salt, forming a clear syrup, which 

 remains clear for years; the solution takes place at a temperature below a dull 

 red heat, and may be effected in a glass flask. Tantalic acid, obtained by the 

 decomposition of the perchloride, or by the action of sulphurous acid on a solution 

 of the tantalate of soda, differs from that obtained by fusion, inasmuch as it 

 exhibits incandescence when heated, which the other does not. From this and 

 other circumstances Rose concludes that there are two modifications of tantalic 

 acid, the one convertible into the other by heat. He has also examined the 

 various salts which it forms with potassa. 



TANNIN. 



By acting upon some organic compounds with boiling alkaline solutions, in an 

 atmosphere of hydrogen, Rochleder has succeeded in decomposing several, and 



