On the Analysis of Earths, 365 



ihe tubulure, or opening, at the top of the retort, and im- 

 inediatclv stop it so as to be air-tight. 



III. When no more gas is Hbcratcd by the addition of a. 

 fresh portion of acid, assist the action by heat, and transfer 

 the cvHndcr containing the gas into hme water; the car- 

 bonic acid will now be absorbed ; the loss of the whole 

 bulk, after deducting the air which was contained in the 

 retort, indicates the quantity of carbonic a<?id contained in 

 the stone. 



IV. The substance from whidi the carbonic acid has been 

 expeHcd must be diluted with double its weight of water, 

 and filtered ; the insoluble part, if any, put aside for further 

 examination. The solutioa may contain lime, magnesia, 

 alumine, barytes, and strontia. 



V. In order to ascertain if barytes or strontia be present, 

 dilute a small portion of the solution witli 24 times its bulk 

 of water, and drop into it a solution of sulphate of soda. 

 If barytes or strontia (or both) be present, a cloudiness will 

 take place, and a white precipitate will gradually be depo- 

 sited. 



VI. Having thus investigated the presence or absence of 

 these earths, our next object is to separate them. Suppose 

 they should both be contained in the fluid ? For that pur- 

 pose, add a solution of sulphate of soda till it produces no 

 further clotuiincss ; when the precipitate has subsided, col- 

 lect it on a filter, wash and dry it. 



VII. Boil this precipitate, with four times its weight of 

 carbonate of potash, in a sufticient quantity of water for at 

 least one hour, suppKnng this fluid as it evaporates, then 

 sufler the insoluble part to subside, and wash it. 



\TII. Transfer the insoluble part of the last process into 

 nitric acid of the specific gravity 1-4, diluted with an equal 

 Weight of water. The carbonate of strontia which it con- 

 tained w ill be dissolved, but the barytes will not be acted 

 upon : the weitrht of the latter, deducted from the weight 

 iif the whole, gives the quantity of each ; or the two may 

 be separated by addinir to the nitric solution barytic water 

 till no further precipitate ensues : the barytes in this case 

 will seize tlie acid, and the strontia will be thrown down; 

 but in this case it is essential that the mtric solution of the 

 «arth is perfectly neutral, or has no excess of acid. 



IX. The strontia and baryt.es being thus separated, heat 

 the fluid and drop into it a boiling solution of carbo- 

 nate of ?oda: the precipitate which falls down mav con- 

 sist of all the remaining earth^ which were contained in the 



solution 



