88 Dr. Schunck on the Formation of Indigo-blue. 



mixture of alcohol and ammonia. This sometimes dissolved the 

 whole of it, sometimes only a part. The insoluble portion, when 

 there was any present, had the appearance of a dark brown 

 powder, and consisted of the body to which I have given the 

 name of Indilmmine. After having been treated repeatedly with 

 alcohol and ammonia until nothing more was dissolved, and then 

 with muriatic acid, and lastly washed with Vater, it was con- 

 sidered pure. The alcoholic liquid filtered from it was dark 

 brown. On adding to it an excess of acetic acid, an abundant 

 dark brown deposit was formed, consisting of a substance which 

 I had not previously observed, and to which I propose to apply 

 the term Indifuscine. It was collected on a filter, washed first 

 with alcohol, then with hot water until all the acetate of am- 

 monia and acetic acid were removed, and lastly agitated with a 

 little cold alcohol, filtered off and dried, when it had the appear- 

 ance of a dark brown or reddish-brown powder. By repeating 

 the process of solution in alcohol and ammonia and precipitation 

 with acid, its further purification was effected. The alcoholic 

 liquid filtered from the indifuscine was mixed with an alcoholic 

 solution of acetate of lead, when an additional quantity of the 

 same substance was precipitated in combination with oxide of 

 lead in brown flocks. The filtered liquid, containing an excess 

 of sugar of lead, was mixed with ammonia, which gave a brown- 

 ish-yellow precipitate, consisting chiefly of indiretine in combi- 

 nation with oxide of lead. This precipitate, after being filtered 

 oft', was treated with dilute acetic acid, which removed a consi- 

 derable quantity of oxide of lead, and after being again filtered 

 off" and washed, it was completely decomposed with boihng dilute 

 muriatic acid. The indiretine which was separated collected in 

 the boiling liquid in the form of brown, half-fused masses, which 

 were separated by filtration while the liquid boiled, washed with 

 boiling water, and then treated with a small quantity of cold 

 alcohol. The alcohol acquired a dark brown colour, and after 

 being filtered from a little undissolved indifuscine, was evapo- 

 rated to dryness, when it left the indiretine in the shape of a 

 brittle resinous residue, which was purified by being again dis- 

 solved in cold alcohol. 



That part of the product of the action of acids insoluble in 

 caustic soda was usually of a dark bluish-purple colour. It was 

 treated with boiling alcohol until nothing more dissolved. The 

 alcoholic liquid, which had a dark brownish-purple colour, was 

 filtered boiling hot from the insoluble portion, consisting chiefly 

 of indigo-blue, and then mixed with ammonia and an alcoholic 

 solution of acetate of lead, which gave a brown precipitate con- 

 sisting of oxide of lead in combination with indifuscine, and such 

 other products as had not been completely extracted by the 



