ANALYSES OF TALC AND MICA, gg5 



swelling, which only spreads in the loose parts under the 

 skin ; and scarifying freely the parts already swoln, that the 

 effused serum may escape, and the matter be discharged, 

 as soon as it is formed. Ligatures are employed in America, 

 but with a different view, namely, to prevent the poison 

 being absorbed into the system. 



X. 



Analyses of various Minerals, hy Mr, Klaproth, 

 (Concluded from p» i55.J 



A 



Analyses of talc and mica, 



MONG the minerals which are most commonly known Talc and mica 

 there are several, the analysis of which deserves to be ve- '■^<l"i''e to be 

 ^ J „ ^, „ . ^1 • X •„ ,. discriminated. 



peated, tor the purpose or correcting their dassmcation. 



Though talc and mica may be distinguished from each other 

 in strongly marked specimens, which serve as types of the 

 two species, they have a great deal of similitude in their 

 external characters. But as nature is far from having 

 separated minerals by limits as well marked, as those we 

 are obliged to employ in our systems, in order to facilitate 

 a knowledge of them, there are found between mica on the 

 one hand, which belongs to the argillaceous genus, and talc 

 on the other which belongs to the magnesian, a great many 

 minerals, occupying various places between the archetypes 

 of the two species, and perplexing the mineralogist in his 

 determination where to place them. 



Thus Mr. Haiiy has classed among the talcs several mine- 

 rals, which he is apprehensive will not ultimately be allowed 

 to retain their place. ** I confess," he says, " that among 

 the minerals I have included under the name of talc, there 

 are perhaps several, which chemical analysis will not suffer 

 to remain there : but it appears to me at present premature, 

 to make any change in this part of the system ; particularly 

 as I findv^e have no analysis of pure talc, that is not very 

 old. This, therefore, should be reexamined, that we may 



Vol. XXVII. — Nov. 1810. Q have' 



