C 72 ] 



(1) b. On adding the tin&ure of galls, a 

 purple-coloured precipitate will appear, which, 

 if in any quantity, will be almoft black ; but if 

 the fixed air be firft fuffered to evaporate, and the 

 iron to precipitate as above, the liquor will ef- 

 fect no change with the tin&ure of galls. 



(2) c. On adding the fmalleft quantity of 

 Pruffian lixivium, a beautiful blue colour will be 

 precipitated. The Pruffic acid, uniting with the 

 iron, forms Pruffian blue ; neither will this hap- 

 pen, if the precipitation a. be fuffered to take 

 place firft. 



d. On adding a little folution of foap, the 

 water will become turbid, and white flakes will 

 be precipitated to the bottom of the veflel ; the 

 alkali of the foap uniting to the fixed air, and 

 the iron to the oil, forming a metallic foap. 



e. On adding a folution of volatile liver of 

 fulphur, a precipitate of a very dark green co- 

 lour is formed. The fulphur combining with the 

 iron, becomes infoluble in the water. 



B. f. The fixed air may be detected as de- 

 fcribed (page 46, a. e.) 



(1) Tincture of galls is made hy infusing pow- 

 dered galls in spirits of wine. 



(2) Prussian lixivium is formed by digesting 

 Prussian blue with caustic vegetable alkali and 

 water, and then adding a little distilled vinegar to 

 neutralize any superabundant alkali^ if alkali 

 should prevail. 



VITRI- 



