196 Of the Arsen ic 



grey fliclls and rinds, and is alfo derived from cala- 

 my, but in appearance they greatly differ, which 

 muff, be owing to different circumftances and caufes, 

 of which I am entirely ignorant, and of which no 

 explicit account is any where given. Here again, 

 we give Pomet's deicription of the tutia the prefe- 

 rence to that of any other writer. 



' The tu/ia, fays he, denominated Alexandria 

 c na, oXfaJpodium Gr^ecorum, is a metallic fpecies, 

 4 formed like fcales or gutters (or rather, happens 

 c to be fo formed) of different fizes and thicknef- 

 c fes, internally even and fmooth, but externally 

 ' like a fhagreen, being befet all round with grains 



* of the fize of pin-heads, whence it had the name 

 c tutia botrytes. The tutia fold in ? France comes 

 6 from Germany * (alfo from Sweden, according 

 to Lemery, in his dictionary of drugs) ' where it 

 4 is prepared from brafs. We muft not imagine, not- 

 *-" v/ithflanding its being affirmed by almoft all an- 

 4 cient and modern writers, that tutia is derived 

 c from yellow copper, and arifes at the fame time 

 c with the pompbelyx ; this is falfe, the tutia ad- 



* hering to the earthen cylinders, or rollers, fuf- 

 6 pended in brafiers furnaces, for the purpofe of 

 4 catching the fume of the metal, whence the tutia 

 c has its /hell or gutter-like form, and fome of the 



* pieces have earth (till flicking to them. 'Tis ex- 

 c ternally of a beautiful moufe colour, and inter- 



* nally of a white yellowifh caff, not eafily broke 

 4 to pieces', &c. 



Here we have the form of our tutia plainly enough 

 defcribed, only the reader is not to- (fumble at our au- 

 thor's making a diftinction between brafs and yellow 

 copper, and allowing the tutia to be derived from the 

 former, and not from the latter-, whereas brafs and 



yellow 



