144 Analyses of Books. [Feb. 



ammonia; the resulting precipitate affording, with sul- 

 phuric acid and potash, crystals of alum. The liquid which 

 passed through the filter from the iron and alumina, afforded 

 a precipitation on the addition of oxalate of ammonia, and 

 afterwards magnesia was procured from it by the usual 

 process. A portion of the iron precipitate was dissolved in 

 acid, and to the neutral solution, benzoic acid was added, 

 which threw down the iron. The solution to which some 

 carbonate of soda was added was evaporated to dryness. 

 No residue ensued on the addition of water, indicating the 

 absence of manganese. 



The iron precipitate, when dissolved, afforded powerful 

 indications of the presence of that metal, by prussiate of 

 potash. In the solid state it was not affected by the mag- 

 net. The results of the analyses are : — 



Peroxide of iron • .81-666 



Alumina 6*866 



Silicious matter ....... 6-000 



Lime 2-000 



Magnesia 0-468 



Loss, probably water 3*000 



100-000 

 The quantity of mineral which could be afforded for the 

 purposes of analysis was, however, too small to determine 

 directly whether water was present as a constituent. The 

 relative proportion of the ingredients are 



Peroxide of iron 5£ atoms 

 Alumina ... 1 atom 

 Silica .... 1 atom 

 but as it is not easy to conceive distinctly how such a com- 

 bination can exist, I am rather inclined to adopt the opinion 

 that the alumina and silica are mechanically mixed with 

 the oxide of iron. 



Article VIII. 



Traite Experimental de electricite, 8fc. Par M. Becqtjerel. 

 Tome II. Paris, 1834. 



The appearance of this volume cannot but be regarded by every 

 cultivator of science as a great boon. The author has undertaken to 



