334 SELECTED ARTICLES. 
ART. LVII.— UPON A REDDISH BLUE COLOURING MAT- 
TER, WHICH FORMS FROM THE DECOMPOSITION OF 
OSCILLARIAS. By Prof. Nees d'Esenbeck, of Bonne. 
M. Blufe, of Aix la Chapelle, having sent a quantity of 
Conferva?, procured from the warm springs of that place, to 
M. Nees d'Esenbeck, at his request; a glass vessel containing 
them, and filled with mineral water, was received by him on 
the 15th of December, 1834. They were not, however, in 
the state requisite for studying their characters, and the ves- 
sel remained in a room well lighted, but not exposed to the 
sun, in which the temperature varied from 8° to 10° R. On 
the 8th of January, the water which covered the green, slimy 
deposit, exhibited a singular and beautiful play of colours. It 
was blood-red when viewed from above, and a beautiful 
sky-blue when held against the light. Upon opening the ves- 
sel, an insupportable marshy exhalation, combined with sul- 
phuretted hydrogen, issued from it. The fluid was separated 
by the filter and distilled water poured upon the deposit; this, 
at the end of twenty-four hours, assumed the same deep hue. 
This operation was repeated during eight days, and always at 
the end of twenty-four hours a beautiful coloured liquid was 
obtained ; so that the small quantity of half putrid oscillarias 
afforded a rich source of colouring matter. The smell of sul- 
phuretted hydrogen disappeared after the second maceration, 
and the strong marshy odour alone remained. The conferva? 
were slowly reduced to a slimy deposition. The following 
experiments were then made on the filtered water, possessing 
this beautiful colour: 
In a glass tube, exposed to the rays of the sun, the colour 
remained until the end of three weeks, but this colour was 
equally long a time in disappearing in a glass excluded from 
the light: during the evaporation of the liquid, an intolerable 
stench was generated, and the residue of a violet colour, when 
washed with alcohol, continued to emit the strong odour of 
animal excrement. This residuum was almost insoluble in 
