MAGNESIAN EARTH. 3 C 2 1 



Proportion* 

 tabulated. 



100,20 



It is from thefe remits that I denominate this earth native It may be called 

 magnefia. It is doubtlefs found mixed with a little filex; buf |jj* /gjjJSJ, 

 if the title of native alumen is given to the alumenous earth of 

 Halle in Saxony, which contains 24< parts of the fulphate of 

 lime; if the name of native magnefia is given to that of Mo- 

 ravia, announced by Mitchacl, of which 100. parts. contain 50 

 of carbonic acid; it appears tome that the earth which I de- 

 fence has a much better title to the name which I have 

 given it. 



The earth of Baudiflero affords a fubject for interefting ob- Suppofed to be 

 fervations in the inveftigation of its origin. Many facts lead decompofition of 

 me to believe that this earth and the Corneen (lone or Cacho- the Corneen 

 long, defcribed and analy fed by my colleague Bonvoifin, are j* one or Cacli »- 

 both of the fame nature. It appears to me that Cacholong at 

 a certain point of its decompofition forms what Bonvoifin calls 

 the hydrophane of Piedmont, and that in its complete decom- 

 pofition it forms the magnetian earth of which I here give the 

 analyfis. Bonvoifin has declared himfelf of an opinion pre- 

 cifely contrary to this ; for he has fuppofed that this earth, far 

 from being the product of the decompofition of Cacholong, 

 is the element of its formation. Our colleague Gioanetti is of 

 the fame opinion. In thefe two hypothefes, the change of 

 one earth into another is manifeir, that is to fay, the change 

 of filex and alumen into magnefia in my method of confider- And therefore 

 ing the matter; (for it is principally of thefe two earths that th at either alu- 

 Cacholong and Hydrophane are compofed, from the analyfis -, s changed into 

 of Bonvoifin ;) and the change of magnefia into alumen and magnefia, 

 filex according to the hypothefis of Bonvoifin and Gioanetti. ~^£* e con * 

 As this fubject appears to me to be very interefting, I intend 

 to make a comparative analyfis of thefe Hones at the differ- 

 ent degrees of their decompofition or entering into the ftate 

 of agate (agatifation) which fliall be the fubjedt of another 

 memoir. * 



4 



Voi. XII.— Supplement. Y , There 



