Q$4t MAGNESIAN EARTH. 



The common unfaturated carbonate of potafli forms aifo 3 

 precipitate with them. 



When this carbonate ceafes to trouble the liquor, and that, 



after being left to fettle and being filtered, the clear liquor is 



fubmitted to ebullition, it becomes troubled again and throws 



down a fecond time an earthy precipitate. 



But not if fa- Finally, if inflead of the unfaturated carbonate, the car- 



turated with c. bonate of potato, well faturated with acid is ufed, there is not 



the lead precipitate formed. 



The earth is Experiments, which I will relate, (new not only that the 



jure magnefia. earth diflfolved by the acids is magnefia, but that there is not 



mixed with it the lead particle of lime, which can be difcovered 



by the oxalate of ammonia, that there is no trace of alumen 



in it, which the faturated carbonate of potafli precipitates, 



and does not again diilblve ; that it does not contain the lead 



oxide of iron, that can be indicated by the pxuffiate of lime ; 



?md finally, that it is magnefia perfectly pure. 



As is ffiewn by This refu.lt is farther confirmed by the fulphate of magnefia, 



the fulphate. which the cry utilization of the folution of this earth in (uU 



phuric acid yields etftlufively. 



Iftfoluble refidue ^he aCK * s m diiTolving this earth leaves a refidue, the quan^ 



or file* about tity of which feems to be variable; that which the fulphuric 



toe 6th, ac j ( j j eaves i s conftantly more than what is left by the muriatic 



or nitric acids, An hundred and twenty grains of this earth, 



after being well lixiviated in pure water, left a refidue of 



which the weight, in the different experiments which I made, 



did not ever exceed 17 grains, and never was lefs than 14. 



The (tony variety was that which in general gave the mofl 



of this infoluble rehdue. Many experiments, which I have 



made, and which it would be ufelefs to repeat here, have con* 



vinced me that this refidue is perfectly pure filex. 



Component The eartn °^ Baudiffero, from the preceding experiments* 



parts recapitrj» confifts entirely of magnefia with a little carbonic acid, a fmall 



quantity of filex, and a very minute portion of fulphate of 



lime, with, in the flony variety, fome traces of muriate o£ 



magnefia. 



(Tq be concluded in the Supplement.) 



Experiment^ 



lated. 



