Analyßs. 47 1 50. The depofite on the filtre from the alkaline folution may then confift of mild flronthian, ba- rvtes, and calx, as alfo of argill, ülex, and calx j " of iron. - I# Xo feparate them, the whole, or all that is eafily foluble, lhould be diflolved by digeflion in nitrousacid; the digeftion need not be obfti- nate, as only the argill, filex, and calx of iron, can make any confiderable refiftance, and they may afterwards be treated apart, as in No 34 and 41. * . 52. The barytic flronthian and calcareous earths being held in folution together, perh'aps with fome portions of argill and calx of iron, the tvvo laft lhould be got rid of by precipitation with cauftic volatile alkali, and afterwards fepara- ted from each other by the means already often mentioned. 53. The folution is now fuppofed to contain only the three firft earths; to afcertain this point it fhould firft be well boiled, to expel the fixcd air that might have iSeen.abforbed, and then a fmall portion of it eflayed with flronthian lime water; if this produces a prccipitate we may be alTured that calx exifts in the folution, otherwife not. , ca lf flronthian hme-water produces no pre- cipitation, we fhould efl'ay another portion of the folution with barytic lime-water; if this produces a precipitate (flronthian lime-water producing none), we may infer that flronthian exills in the folution, and not calx; but, if barytic Urne wa ter produces none, we may conclude that barytes only exifts in the folution; if both flronthian lime-water and barytic lime-water occafion preci- pitates, it reniains dubious whether the three * H h 4 «tths