V^ Comhinations of Barytes with Silex and Alumnt, 



Experiment 2. The pure nitric, muriatic, and acetous acids totally diflblve this fubilance-^ 

 Its folution, in any one of tiiefe acids, immediately affords a flocculent precipitate by ammoniac; 

 Thefe folutions become gelatinous by evaporation, and when completely dried, the filex is. 

 again developed in poffeflion of all its properties. It cajinot,, therefore, be doubted, but that 

 faarytes, as well as ftrontian, poffeflL's the property of combining with filex, and of rendering 

 Lt foluble, even in the weakeft acids^ 



Experiment 3. Nine parts of cauftic barytes were mixed with one part of alumine-, newly 

 feparated from its folvent, and ftill moift ; and the whole was fubjefled for a quarter of an 

 hour to ebullition, with a fufficient quantity of water. Much undiffolved matter remained. 

 The filtered liquor had a (lightly cauilic tafte, rather ftronger than, that of ftrontian treated 

 in the fame manner. It foon became covered with a white cruft by the abforption of carbonic 

 acid from the atmofphere ; but it did not cryftalize, though the quantity of water was not 

 Sufficient to have prevented that effeil, if the alumine had not been prefent. 



A drop of muriatic acid poured, into a glafs of this folution, produced a flocculent cloud, 

 which was rediflblved by agitation. A fecond and third drop produced the fame effe£l, until 

 tile greateft part of the barytes was faturated ; but at length the precipitate being no longer 

 diffolved by the motion impreffed on the fluid, an excefs of acid diffolved it. When the 

 fluid was entirely faturated with acid, the flocculent matter was again reproduced by ammoniac j 

 and when this laft addition ceafcd to produce any effa6t, a very abundant precipitate was af- 

 forded by the carbonate of potafh. 



We fee, therefore, that barytes, as well as ftrontian, diflblves alumine, and even more abund- 

 antly i neverthelefe, there ftill remained in the refidue a portion of alumine and barytes, 

 which were not diffolved, and appeared to be in a ftate of intimate combination. 



Sufpe£ling that this more abundant folution of alumine by barytes, than by ftrontian, might 

 be owing to a greater quantity of barytes having been ufed in this experiment than of ftron- 

 tian in the other ; I made a fecond, in which 1 mixed equal parts of barytes and alumine, and 

 boiled them as before. The liquor ftill gave figns of an abundant folution of alumine and 

 barytes, and about half the matter remained in the form of a white powder infoluble in water, 

 in which the acids demonftrated the prefence of thefe two earths- in combination. 



TheYame effe£ls take place between ftrontian and alumine, and it is not furprifing that 

 this property extends itfelf to the alkalis ; for when, alumine is precipitated by potafh, and 

 rather too much. of this fubftance is added, the earth always retains fome traces of the alkali, 

 however carefully it may be wafhed. Befides which, we have examples enough of glafs 

 which becomes foluble, or infoluble, according to the quantity of alkali ; and a ftill more 

 ftriking inftance is afforded of potafh. in hard ffcones,. which cannot be feparated by any me- 

 chanical means. 



The truth of what is here advanced, may be very fimply fliewn, by pouring a faturated 

 liot folution of-barytes into a folution of the muriate of alumine. A precipitate in flakes will 

 iirft be found, which will be rediffolved by a new quantity of the folution of barytes ; and if 

 before this precipitate be entirely, rediffolved, it be feparated from the fliiid, it will be foutid 

 do he compofed of alumine and barytes. 



Barytei 



