368 Analysis of Stones. 



pendcd in \va.4nng inay be added to the fluid which passed 

 through the fiUer in obtaining this earth. 



VI. The fluid from which the silcx has thus been ol)- 

 tained, i^ then to be concentrated by evaporation and 

 mingled \\ ith a heated sohition of carbonate of potash till 

 no more precipitate ensues. The precipitate must be sepa- 

 rated by the lilter, washed and dried. It may contain alu- 

 niine, lime, magnesia^ glucinc, and yttrla, beside metallic 

 oxides. 



VII. Transfer the precipitate obtained in the last process 

 mto a solution of potash, and boil it for half an hour4 If 

 alumine and glucine were present, they will both be dissolved 

 in the potash, while the other substances remain mitouched 

 in the form of a powder. 



VIII. To separate the alumine, decompose the solution 

 by the addition of an acid, taking care to add the acid em- 

 ployed in excess, so that the precipitate which first appeared 

 becomes rcdissolved. Having done this, drop into it a so- 

 lution of carbonate of ammonia in such quantity that the 

 liquid tastes of it. By this addition the whole of the alu- 

 mine will be precipitated in white flakes, and the glucine 

 will remain dissolved provided the quantity of carbonate of 

 ammonia used be not too small. The liquid must now be 

 fdtered, and the alumine washed, dried, and ignited j its 

 weight may then be ascertained. 



IX. The fluid from which the alumine has been sepa- 

 rated may be boiled for some time; tlie glucine, if it con- 



■■tains any, will be precipitated, which may be dried and 

 weighed. 



X. The insoluble part left in Process VII may now con- 

 tain lime, magnesia, and some metallic oxide : let it be dis- 

 solved in diluted sulphuric acid, and the solution evaporated 

 to dryne?:^ ; on the dry nvass pour a small quantity of water, 

 and digest it for a few minutes ; the water will dissolve the 

 sulphate of magnesia and the metallic sulphates ; but the 

 lime combined with the sulphuric acid will remain undis- 

 solved : let it be heated red-hot in a crucible, and the quan- 

 tity of lime determined, as directed before, page 143. 



Remark. — If yttria be suspected, let the residuum of Pro- 

 cess VII. be treated with carbonate of ammonia, which will 

 dissolve the yttria and leave the other bodies ; then proceed 

 as above. 



XI. The solution from which the lime has been separated 

 must next be copiously diluted with water; add a small 

 excess of acid, and then drop into it a solution of carbonate 

 of potash as long as a precipitate ensues. This will sepa- 

 rate 



