, OnthtDecompofitionoftheAcidofBarax. a6r 



and to the time of kindling and extinguifliing the fire. I now found that bufinefs of import* 

 ance would prevent me from continuing my labours for fome months ; I poured two otbcf 

 ounces of the muriatic acid upon the fait, befides the fluid fo^ often drawn ofF by diftillation, 

 and left the mixture at reft. 



Exper. XI. XII. XIII. XIV. When my bufinefs was finiflied, I again undertook the 

 diftilling of the mixture, which had been fo long digefting in the cold, for the feventh time, 

 and obtained the fame refults as in Exper. X. Nor was there much difference obferved iu' 

 the XII. XIII. and XIV. experiments. 



Exper. XV. I now poured the fluid obtained by the XIV, experiment upon the fait (which 

 had*acquired here and there yellow fpots brighter in hue), and then proceeded, as before, till 

 the fait became dry ; upon which, when the retort was cool, I poured one ounce and three 

 drams of the muriatic acid in addition, and allowed the mixture to digeft gently for fome days. 



Exper. XVI. In this twelfth diftillation there appeared a large quantity of flocculent fub- 

 limate, looking almoft Itke branches hanging down, and in many places of a yellow colour ; 

 it extended even into the neck of the retort,, and almoft covered the interior aperture of the 

 tube. 



Exper. XVIL The thirteenth diftillation produced the fame phenomena. Upon the 

 lowermoft furface of the mafs of fait, many light-brown fpots appeared as foon as the fluid 

 was fo much evaporated that no more of it could be feen upon the fait. 



From all thefe circumftances I now believed the mafs of fait, byadigeftion of twenty-two 

 days, and feven diftillations, fropi experiment XI. to XVII. (that is, by a digeftion of fifty- 

 four days, and thirteen diftillations, in the whole), to be fo far decompofed as to admit of a 

 feparation of fome of its conftituent parts. I therefore fuppofed 1 might leave off applying 

 only a digeftive warmth, and proceed to a greater degree of heat. 



Exper. XVIII. Having poured out the fluid obtained by experiment XVII. and re- 

 placed the phial, I increafed the degree of heat. By this the retort became quite obfcured, 

 firft by fumes, and afterwards by a quantity of white fublimate, attaching itfelf to all its fides, 

 which however had not the appearance of common fedative fait. As I increafed the heat, 

 the fublimate grew darker in colour, afterwards became black and frothy, and at length ran 

 down the fides of the retort, being almoft wholly blackened by it, 



Exper. XIX. Wh\h the retort was ftill warm, I poured into it the fluid obtained by ex- 

 perjnient XVII. having firft watered it a little; when almoft in the fame inftant a very 

 agreeable phenomenon took place : cryftals perfeftly white fhot forth fuddenly, and all at 

 once, from every fide of the black mafs, covering the fides of the retort. '^ he diftillation 

 being continued, thefe cryftals were at length diffblved and entirely removed. The fuperna- 

 tant fluid was as ufual almoft colourlefs. When the mafs of fait appeared dry, the fire was 

 increafed, as in experiment XVIII. and the fame appearances, as above related, took place; 

 firft, the fublimate appeared white ; then black frothy, and flowing down the fides. 



Exper. XX. I proceeded as in experiment XIX. to pour back the diftilled fluid. Inftantly a 

 Vol. I1I._S£PTEMBER 1799. Mm number 



