at Ltmington Priors. odh 



2n any of the mineral acids : they all take up a little of it, 

 make a brifk eftervefcence, and excite heat when firft ap- 

 plied ; but neither by a long digeftion, nor by boiling, could 

 I faturate the acids ; nor, by putting a very fmall quantity of 

 the powder into a large quantity of acid, could I completely 

 diflblve the powder. 



2. But by the ufe of the blow-pipe it readily appeared 

 that this fediment is no other than the oxydes of the two 

 metals fo frequently mentioned, iron and manganefe. It 

 may be made magnetic ; it gives the hyacinthine colour to 

 borax ; the colour is deftroyed by continuing the fufion, and 

 may be renewed by removing the globule to a filver fpoon : 

 tufed with ibda and nitre it makes a blue or a green globule. 

 As the fediment may be procured in fufficient quantity, I 

 repeated the laft experiment on a larger fcale : fome nitre 

 being mixed with it, the mafs was pulverifed, and fufed in a 

 crucible; when taken out of the fire it was green, and dif- 

 folved in water, to which alfo it imparted a fine green co- 

 lour : in a day or two a yellow ochre was depofited, when 

 the folution became blue ; from this liquor a powder fub- 

 fided by evpofure to the air, which was manganefe. (See 

 Scheele'b Effay on Mang. xxxvi. B. 



3. Puriuing the obfervations of the effecls of the mineral 

 acids confirms this conclufion. I mixed fome of the fedi- 

 ment with powdered charcoal, and expofed the mixture to a 

 Orong red heat : it became of a light brown colour, and 

 now proved to be readily foluble in all the mineral acids. 

 (See Scheele's Efiay on Manganefe, xxxviii. A.) With 

 the muriatic and nitric it formed a gelatinous compound. 

 'I he fulphuric acid, diluted, was foon faturated; the liquor 

 was eyaporated, and depofited white cryftals, the form of 

 which is rhomboidal. This is a triple fait, the bafe of 

 Which is iron and manganefe. If there be a fmall excefs of 

 acid, the taf'te is very like that of fulphat of argill. The fame 

 fait may he obtained by boiling the fulphuric acid with the 

 fediment itfelf, and continuing the boiling till the mafs is be- 

 A a 3 corns 



