^ From STRONTIAN. 29 



71. The earth attrads tartarous acid more forcibly than al- 

 kalis do. Add Strontitic water to tartrite of potafs, and tartrite 

 of Strontites will defcend ; but its attradion is weaker than 

 that of barytes or lime, for the folutions of either of thefe 

 earths renders tartrite of Strontites turbid. The fame place is 

 due to this earth in its attradion for fluoric acid as with acid 

 of tartar ; barytes and lime exceed it, potafs is feebler. 



72. With refped to nitric and muriatic acids, the order 

 feems fomewhat different. Here fixed alkalis appear to predo- 

 minate. Yet of this, after feveral trials, I was fomewhat un- 

 certain, in confequence of peculiar phenomena that occur. 

 When abfolutely cauftic potafs is dropped into a diluted folu- 

 tion of muriate of Strontites, tranfparent cryflalline flakes ap- 

 pear ; but long before all the earth is difengaged, the alkali 

 ceafes to occafion more precipitation, and it may be afterwards 

 added in quantity, without producing any vifible effed. If, 

 however, an eflervefcent alkali be now poured in, a copious 

 curdy precipitate will be formed. Two hundred grains of 

 Strontian fpar were diflblved in muriatic acid. To the folution, 

 diluted with more than an equal quantity of diftilled water, L 

 added potafs, till it no longer occafioned depofition. I permit- 

 ted the precipitate to fubfide, and then poured in fome potafs, 

 which caufed no vifible change. The clear liquor was decant- 

 ed off, and the remaining portion filtered. The precipitate, 

 when coUeded and weighed, amounted only to 24 grains. 

 With the clear liquor, I mixed carbonate of potafs, and 1 ob- 

 tained an abundant white precipitate This I walhed, and dried- 

 by a gentle heat ; it weighed 170 grains. On another occafion, 

 I diffolved a fimilar quantity of the mineral in the fame acid, 

 and after dilution I added the alkali very flowly. The matter 

 feparated aflumed the form of quadrilateral lamellar cryftals, 

 fome of which, unattached to any others, fhowed the wedge 

 fhaped margin like an ordinary cryflal of Strontites ', frequently 

 they adhered to each other, fometimes appearing in arborefcent 



ifigureSo 



