MINERAL MANURES. 195 



form in which their constituents are employed. Excrements 

 gave much more than their ash, when each were employed 

 separately. In the field, he found that ammonia-phosphate of 

 magnesia did not affect the development of the grain, that it 

 injured the formation of the straw, and that mineral manures 

 without ammonia retarded vegetation. 



Disintegratioii of Rocks. — Soils being formed by the disin- 

 tegration of rocks, the study of this point is of some im- 

 portance in vegetable physiology. 



Ebelmen (Comptes Rendus, xxvi. and Ch. Gaz. vi.) gives, 

 as conclusions from a series of analyses, 1. That silicates, 

 which contain no alumina, lose, on disintegration, silica, lime, 

 and magnesia : sometimes the iron disappears with the bases, 

 and at others, remains in the residue as peroxide. 2. Silicates 

 containing alumina and an alkali, and even other bases also, 

 become richer in alumina on disintegration ; and this alumina 

 retains the silicic acid and assimilates water, while the other 

 bases, with a portion of the silicic acid, disappear. In this 

 case, the residue approaches in composition to a hydrated 

 silicate of alumina. 



W. B. and R. E. Rogers have given the results of a series 

 of experiments (Amer. Journ. 1848) upon the solvent power 

 of pure and carbonated water upon mineral compounds, by 

 which they prove in two ways, 1st, by an extemporaneous 

 method with the tache, and, 2dly, by prolonged digestion at the 

 ordinary temperature, " the solvent and decomposing power 

 of pure and carbonated water upon all the important mineral 

 aggregates, as well without as with alkaline ingredients." 



Phosphate of Lime in Basaltic Rocks. — Deck (Chem, Gaz. 

 vi.) has, by recent analyses of some basalts, proved the pre- 

 sence of phosphate of lime in igneous rock, and thereby con- 

 firmed those of Mr. Forbes, in contradiction of those by Prof. 

 Kersten. 



Artificial 3Iineral Manures. — Liebig gives the following 

 proportions of salts, as the basis for manures. 1. 2| pts. 

 carbonate of lime and 1 pt. potash (or 1 pt, of a mixture of 



