Facts for a History of the Gallic Acid. 205 



an excess makes it pass to the colour of pea blossom ; and 

 it' we add some drops of nitric acid, the liquor becomes rose- 

 coloured. The same phajnoir.eaa take place with barytes. 



This solution assumes a colour more or less greenish with 

 the carbonate of soda ; with that of ammonia the colour does 

 uot change. It is a deep brown with caustic potash, and 

 with ammonia it is of a reddish brown. 



With the green sulphate of iron the colour is violet blue, 

 which is constant with this sulphate; an excess does not 

 change it. With the nitrate of mercury we obtain a yellow- 

 precipitate; it is white with the acetate of lead and the mu- 

 riate of tin. 



The solution of this acid presents no pha;nomeaou with 

 the oxymuriatic acid. 



It forms an abundant precipitate with glue. 



The same experiments have been made upon the acid ob- 

 tained by M. Richter's process : the results were similar, 

 with this sole difierence, that it formed with glue a very 

 small quantity of precipitate. 



Sublimed Acid of M. Deijeux. 



The solution of this acid in warm water liberates an aro- 

 matic smell, and we perceive at the surface of the liquor a 

 slight oily pellicle. 



Exposed to the contact of the air, this solution becomes 

 brown. It reddens a little the tincture of turnsole; lime 

 water gives it the colour of wine lees, and an excess changes 

 it to the fawn colour ; with barytes we obtain this last shade, 

 and the liquor is immediately covered with an oily pellicle. 



Carbonate of ammonia produces no change in the acid 

 liquor ; carbonate of soda gives it a fawn colour. 



Caustic potash makes it brown; the colour is clearer with 

 ammonia. 



If wc pour into this acid liquor some dro})s of a solution of 

 sulphate of iron, we obtain a blue colour which soon becomes 

 violet blue ; very often also, in place of a blue colour, it is 

 of a deep green. This proceeds', without doubt, from some 

 particular circumstances. I think we may attribute this 

 T 4 phscnomenou 



