ao4 ESSAYS AND OBSERVATIONS 



Lastly, I expofed a few ounces of the 

 ley in an open (hallow veflel fo long, that 

 the alkali loft the whole of its caufticlty, 

 and feemed entirely reftored to the ftate of 

 an ordinary fixed alkali ; but it did not 

 however depofite a fingle atom of lime. And 

 to aflure myfelf that my cauftic ley was not 

 of a fingular kind, I repeated the fame ex- 

 periments with an ordinary foap-ley, and 

 with one made by mixing one part of a pure 

 fixed alkaline fait with three parts of common 

 ftone lime frefh flaked and fifted ; nor could 

 I difcover any lime in either. The firft of 

 thefe contained a fmall quantity of brimftone, 

 and was far from being perfedly cauftic, for 

 it made a pretty briflc effervefcence with 

 acids J but the laft was fo entirely deprived 

 of its air, that it did not diminifti in the leaft 

 the tranfparency of lime-water. 



These experiments feem therefore to fup- 

 port the fourth propofition, and to ftiew 

 that the cauftic alkali does not contain any 

 lime. 



As it feems probable, from the quicknefs 

 and eafe wherewith the alkali was rendered 

 cauftic, that more lime had been employed than 

 what was juft fufficient to extrad the whole 



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