230 Precipitation of one Earth by Another 



quainted with any researches that have been instituted ex- 

 pressly on it. 



In the communication I have now the honour to contribute, 

 I shall do little more than enter on the inquiry, having 

 neither the leisure nor means requisite to prosecute it far ; 

 my hope is that the few results I may be able to bring for- 

 ward, with their applications, may induce others who are 

 more favourably situated to engage in and extend the inves- 

 tigation. 



If lime, whether in the form of hydl'ate or carbonate, be 

 added to any salt of alumine in solution,' the latter earth is 

 thrown down, and a salt of lime formed ; and, after a certain 

 time, judging from the experiments I have made,- and as is 

 reasonable to infer a 'priori^ if a sufficiency of lime be used, 

 the whole of the alumine will be precipitated. 



Magnesia and its carbonate appear to have the same effect 

 on the salts of alumine. 



If lime be added to a salt of magnesia, the effect varies 

 according to the nature of the salt. In the instance of the 

 sulphate, the lime separates the magnesia, — magnesia is 

 thrown down and sulphate of lime formed. In the instances 

 of the nitrate and muriate of magnesia, no change takes 

 place. Nor is there any change when the carbonate of lime 

 is substituted for the hydrate ; even sulphate of magnesia, 

 and carbonate of lime remain unaltered on admixture. 



If lime be added to a salt of iron in solution, whether in 

 the state of peroxide or protoxide, a precipitate is effected, 

 the oxide is separated. A similar effect as to separation 

 takes place, if the carbonate of lime be used. In this in- 

 stance, in the case of the protoxide, a carbonate of iron is 

 formed, which, acted on by atmospheric air, is rapidly decom- 

 posed, carbonic acid gas escaping, and hydrated peroxide of 

 iron appearing. 



Magnesia and the carbonate of magnesia appear to have 

 a like effect on the salts of iron ; and alumine likewise ap- 

 pears to have the same effect. 



If lime be added to a solution of phosphate of lime in the 

 nitric, muriatic, or acetic acid, the phosphate of lime is pre- 

 cipitated, as the acid, the solvent, is neutralised. When 



