316 Intelligence and Miscellaneous Articles. 



and the alumina, precipitated by carbonate of ammonia, was dried 

 and weighed, and its nature was further determined by the fine blue 

 colour which it gave with nitrate of cobalt. 



The oxide of iron separated from the alumina still retained an ap- 

 preciable quantity of lime and magnesia, which were separated by 

 means of hydrosulphate of ammonia. 



There remained to ascertain the substances contained in the am- 

 moniacal solution separated from the oxide of iron and the alumina ; 

 the liquor was treated with excess of oxalate of ammonia, which 

 gave a considerable quantity of oxalate of lime. This salt was col- 

 lected on a filter, dried, heated to redness, and the carbonate of lime 

 resulting was converted into sulphate, from the weight of which 

 that of the lime was deduced. 



The liquor separated from the oxalate of lime was evaporated to 

 dryness, and the saline residue heated to low redness to volatilize the 

 ammoniacal salts. The fixed residue was dissolved in sulphuric acid, 

 the solution evaporated, and the salts deprived of water, heated to 

 redness and weighed ; they consisted of sulphate of magnesia, soda 

 and potash. 



These different salts were decomposed by acetate of barytes, and 

 the magnesia was separated from the alkalies by the usual method ; 

 the potash and soda were estimated together in the state of sulphate, 

 and the potash afterwards separated by means of chloride of platina. 

 The analyses yielded as under : — (1) pale yellow crystals, (2) brown 

 crystals. (1) (2) 



Silica 39-27 38-34 



Lime 32-47 32-05 



Magnesia 6*44 6*71 



Potash 1-46 1-51 



Soda 1-95 2-12 



Peroxide of iron 10' 17 10-02 



Alumina 6*42 8-61 



Oxide of manganese traces 



98-18 99-36 



M. Damour attributes the slight differences of these analyses to 

 accidental admixtures in the crystals employed, and he represents 

 melilite by the formula 



(Al, Fe) Si + 2 (Ca, Mg, K, N)s Si. 



Ann. de Chim. et de Phys., Janvier 1844. 



DESCRIPTION AND ANALYSIS OF HUMBOLDTILITE, AND IDEN- 

 TITY WITH MELILITE. BY MONS. A. DAMOUR. 

 This mineral is found in crystalline masses among the blocks of 

 Somma ; it is usually covered with a slight earthy calcareous coating, 

 which dilute acids readily remove. Small black crystals of pyroxene 

 frequently accompany and traverse it. Its physical properties are 

 perfectly similar to those of melilite. Its colour is generally very 

 pale. Fracture vitreous. Scratches glass with difficulty. Specific 

 gravity 2*9. The crystals are larger than those of the melilite of 

 Capo-di-Bove. Traces of cleavage parallel to the base are discover- 

 able. The form of the crystal is a square prism. 



