Natural History. 409 



which had been written by the Duchess of Cerifalco, after con- 

 finement in a subterranean cave for nine years, in which note she 

 observed, that almost all the last syllables were wanting. — Mem. 

 o/M. de Genlis, iii. 37. 



6. On a peculiar Blue Matter obtained from certain Urines. By 

 M. H. Braconnot. — Dr. Castara, of Luneville, sent a small flask 

 of urine to M. Braconnot, of so deep a blue colour, that it ap- 

 peared almost black. It was voided by a person who had also 

 vomited a matter of a similar colour. This peculiarity had existed 

 for two years. The blue matter retained in suspension was de- 

 posited but very slowly ; it was, however, readily separated by a 

 filter. When well washed, this peculiar substance was pulveru- 

 lent, of extreme tenuity, insipid, inodorous, of a tint deeper than 

 Prussian blue, adhering readily to the fingers or paper, and 

 making blue marks. Cold water had no action upon it ; boiling 

 water took a slight brown tint from it, and then became red 

 by acids, indicating a little solubility. Boiling alcohol had more 

 power over it, and became greenish ; when filtered and allowed to 

 cool, it deposited a slight deep-blue sediment, which had a crys- 

 talline appearance ; the solution evaporated left the blue matter, 

 which, when dissolved in a feeble acid, deposited a portion of 

 fatty matter. 



The alkalies have no affinity with this substance, and change it 

 before they dissolve it. Heated with weak solution of carbonate 

 of potash, it did not appreciably dissolve. A hot weak solution 

 of caustic potash dissolved a part of it, forming a brown liquor, 

 reddening feebly by acids ; but then with ammonia forming a 

 flocculent precipitate and a colourless solution. 



Weak acids readily unite to the blue matter ; if the smallest 

 possible quantity of acid be used, the solutions are brown ; with 

 more acid they are of a fine red colour. Alkalis, earths, fyc, pre- 

 cipitate the blue matter unchanged. It being supposed that the 

 matter possessed some of the characters of a salifiable base, it was 

 heated with water slightly soured with sulphuric acid, in order to 

 separate mucus if any were present. In this way, a yellow-brown 

 solution was produced, nearly neutral, which, by further addition 

 of acid, became bright red. The brown solution, evaporated 

 slowly, gave a residue of a very fine carmine colour, which by so- 

 lution became yellow-brown, but by evaporation again assumed 

 its fine tint. This compound, when put into the mouth, had a 

 slight acrimonious taste, and coloured the saliva blue from the 

 action of the soda in it. 



The red compound, applied in drops on porcelain, left spots, 

 carmine red by transmitted light, but of a golden metallic co- 

 lour by reflected light. They ultimately became blue, probably 

 from the presence of ammonia in the air. When a solution of 



