Laie DifcQverles in Science. 2^1 



tlcular which relate to the frequent change of colour, may be 

 obferved with the utmoft accuracy. 



3d, The operator has it perfeftly in his power, when the 

 foffil operated upon is highly refrailory, to promote the pro- 

 cefs by the immediate addition of more cauftic ley or water, 

 without the leaft interruption, but which cannot be done in 

 the dry way without great lofs of time. 



4th, By this method the operator, if he finds a new earth 

 or metal, obviates entirely the fufpicion of its arifiiig merely 

 from fome modification, or unmaflcing of component parts 

 already known, effefted by the ftrong heat. 



5th, In the dry way, the operation often requires three, 

 and even four hours; but by the propofed wet way it may 

 be efte£ted, with much more certainty than before, in one 

 hour and a half at moft. 



6th, The difagreeable circumftance, attcpded with many 

 difficulties, of the folution of the foffil fubjected to the opera- 

 tion forming a kind of jelly with the acid, is entirely obvi- 

 ated by my method; at leaft, as I have hitherto experienced 

 in all my trials. 



7th, The filver crucible befides, being free from the danger 

 of melting, as was formerly to be apprehended, fuftains very 

 little damage by being ufed. 



XI, Citrfory View of fome of the late Difcoveries in Science. 

 [Continued from Page 152 ] 



V. 



AUCIUELIN, who has civen fo many excellent ana- 

 lyfes of minerals, has defcribed the procefles he employed. 

 The (tone intended to be analyfed is firft reduced to powder; 

 it is then mixed with three times the quantity of potafii, and, 

 the whole being put into a crucible, is expoled to a heat 

 ftrong enough to convert it into a frit. When the veflel is 

 taken from the fire, the frit is thrown into diftilled water ; 

 and, when the matter is dilTolved, different chemical means 

 ?re employed to difcover the fubftances contained ui the foffil. 

 The following are the charaftcrs by which each of the eight 

 K k 3 earth?- 



