EXAiMINATION OF THE OCHROITES. 



a. It is brown. 2. Ochrolt earth, after being freed from c?irbonlc acid and 

 water, by heat, always appears in the form of a cinnamon- 

 brown powder. The intenfity of the colour is ii) proportion 

 to the heat applied. This colour is not owing to the pn-fence 

 of iron, or manganefe, &c. but it is a chara6lerifiic property 

 of the earth. 



3. Notreduci- 3. Ochroit earth included in a charcoal crucible, and ex- 

 ^^^' pofed to the heat of the porcelain furnace, fuffered no change 



whatever. 



4. Not fafibleas 4. Urged by the blow-pipe, it becomes phofphorefcent ; 

 the microcolmic f^kd with pholphate of foda and ammonia, it becomes tinged 

 fait nor borax. . rr- r^- r < • r , i ri^i /• 1 



by it, without eriectmg a (olution or the earth. 1 he lalt ac- 



t quires merely a marbled lemon yellow colour. Borax has 



likewife no chemical efied upon it. This fait only effeds a 

 mechanical divifion. The earth always appears difTufed 

 through the borax in minute^occM/e. 



5. Gives an un- 5. Ochroit earth mixed in different proportions with proper 



even brown as a flukes, and applied for painting of porcelain, proved unfuc- 

 porcelain colour. . ,. , _, ' . , • , ,• , . 1 



' celstul. The painted articles were liglit brown, but the co- 



lour was not uniform; a proof that no combination had been 

 effeaed. 



6. Difficultly 6. Ochroit earth combined with carbonic acid is eafily folu- 

 foluble in acid ifbi^ „,j,|^ efFcrvefcence in acids. The tafte of the folution is 



the earth be , , ^ . _,. 1 r 1 • • c 



pure; but eafily ^'^ry rougu and aitnngent. The concentrated lolutjon is of an 

 if carbonated, ametliyft red colour ; diluted with water, it becomes colour- 



lefs. Ignited ochroit earth, on the contrary, is difficultly folu- 

 Nitrx acid. hie in acids in the cold; if nitric acid be employed, the folu* 



tion is yeliowifli red. 



7. Sulphate of '7. The combination of ochroit earth with fulphurlc acid, 

 ochroit 13 ci\f- is cryftallizable. Tlie figure of the cryflals formed in 



taliizable, and , ^ ,. ,. , „ . , . , 011 rr^, 1 



paleamethyft ^'""^ '"^^^^ ^' ^'""^ fluids is the octahedron. They are heavy, 

 colour. of a pale amethyfl: colour, and difficultly foluble in water; but 



the fulphate of ochroit wit'i excefs of acid, is more foluble ; 

 the figure of the cryffals formed on the fides of the veffel, are 

 needle-lhaped, radiating from a centre. They are more fo- 

 luble than the former, 

 Sulphit- of fida S. If a folution of fulphate of foda be mingled with a folu- 

 dccompofes nnur. tion of muriate or .nitrate of ochroit, a mutual decompofition 

 ochroi"s^. ° takes pliice. A while infoluble precipitate is formed, confift- 

 Theinfoluble ing of falphuric acid united to the ochroit earth. This com- 

 fuiphate of • bination 



echioites. 



