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I was defirous to obferxe the cffecl of crabs' eyes being iiifiifed in 

 vinegar, it being fiiid that they abforb or take away it-; Ibiirnefs, and 

 I concluded that this mull be performed by tlic acute falts before 

 mentioned being altered in iigure, or rendered jnore foft or flexible, 

 fo as to lofe their pungency on the tongue. 1 took therefore, fome 

 new glaflcs, and after mixing in llicni vinegar with crabs' eyes 

 )>roken in fmall pieces, I found, that the long pointed falts I have 

 before defcribed, were altered to a kind of oblong quadrilateral 

 figure riling in tlie middle in form of a pyramid, fimilar to a diamond 

 when polifhed ; thefe are rcprefented infg. ic, aj: P. others were 

 exactly fq,uare, as at O, and others of the fliape reprefcnted at 

 K. But it is to be noted, that thefe particles bore no proportion in 

 point of fize to the faline particles in connnon vinegar, for thefe lall 

 were drawn from much deeper magnifiers, without the help of 

 which, I could not have difcovered their fliapes. And, what I par- 

 ticularly wondered at was, that thefe faline particles were almoft all 

 of the fame fize, which I never obferved in any other fpecies of 

 falts. After the effervefcencc produced by the mixture of the vine- 

 gar and crabs' eyes was fubfided, I drank about a third part of a 

 thimble full of the vinegar, and found that it had no acid tafie, but 

 a bitternefs, fo difgufiing, as almoft to occafion a naufea or fick- 

 jiefs. 



I have alfo pounded white chalk and mixed it with vinegar, and 

 1 found that it produced the fame effervefcencc as the crabs' eyes, 

 and the fame change of figure in the faline particles, and that it alfo 

 took away all the acid tafie of the vinegar. 





