OF ARTS AND SCIENCES. 245 



the toluol passes over, and the acetic acid remains behind in the 

 flask. 



Amnionic hydrate dissolves the metabromdinitrophenylacetic acid, 

 forming a colorless solution if the acid is in excess ; but if the ammo- 

 nic hydrate is added in sHght excess, a green solution is obtained, 

 which turns dark, brown it" a large excess of ammonic hyd]-ate is 

 added, but regains its green color on dilution with water. Both the 

 colorless and green solutions smell of ammonia, and this smell could 

 not be removed by gentle boiling, or by allowing the solution to stand 

 over sulphuric acid, from which we infer that the ammonium salt is 

 a decidedly unstable substance. When either solution is warmed on 

 the water bath for some time it is partially decomposed with formation 

 of a precipitate of metabromdiuitrotoluol, and the green solution turns 

 yellow even when allowed to evaporate spontaneously. Hydrochloric 

 acid threw down from the solution a precipitate of metabromdini- 

 trophenylacetic acid. The ammoniacal solution, prepared with an 

 excess of the acid and freed as completely as possible from an excess 

 of ammonia, gave no precipitate with baric, strontic, or calcic chloride, 

 but with the salts of many of the heavy metals it gave precipitates, 

 of which the following were the most characteristic: — 



Aluminic chloride, heavy, white. 



Ferric chloride^ heavy, very pale bluff. 



Cupric sulphate, heavy, pale blue. 



Mercuric nitrate, heavy, yellowish white. 



Mercuric chloride, a very slight precipitate, i^robably white precipi- 

 tate from the slight excess of ammonic hydrate. 



Mercurous nitrate, heavy, white. 



Plumbic acetate, heavy, white. 



Argentic nitrate, heavy, white. 



The behavior with argentic nitrate is especially characteristic ; if 

 the solutions are strong, the mixture becomes nearly solid from the 

 formation of a white flocculent precipitate, which frequently swells up, 

 forming a little heap or pyramid, and after standing for some hours 

 becomes converted into good-sized crystals. The analysis and proper- 

 ties of this salt are described more in detail below. 



With sodic hydrate a solution of the acid turns a deep Prussian 

 green color, which passes in time into a yellowish brown, this latter 

 color appearing at once when an excess of sodic hydrate is added. If 

 the green solution is acidified, a precipitate is obtained, which, although 

 nearly colorless when dry, becomes purple when moistened with alco- 

 hol. This precipitate was oily at first, and, although it solidified later. 



