58 M. Gorup-Besanez on the use of Ozone. 



Ozone completely removes writing ink ; but printing ink is not 

 attacked by it, at any rate to no perceptible extent : grease spots 

 and mineral colours also remain unchanged, but vegetable colours 

 are completely removed. The method used is as follows : — The 

 air in a sulphuric-acid carboy is ozonized by Schonbein's method, 

 which consists in placing in it a piece of phosphorus 3 inches 

 long and \ an inch thick, and pouring into the carboy as much 

 water at 30° C. as will half cover the phosphorus; the carboy is 

 loosely corked and allowed to stand in a moderately warm place 

 until the air is charged with ozone, which generally requires 

 from twelve to eighteen hours. Without removing the phos- 

 phorus and water, the article to be bleached is uniformly moist- 

 ened with distilled water, and after being rolled up is suspended 

 by a platinum wire in about the centre of the carboy. The roll of 

 paper is soon seen to be continually surrounded by the column 

 of vapour rising from the surface of the phosphorus. The time 

 required for the bleaching depends on the nature of the sub- 

 stance, but never requires more than three days ; paper brown 

 with age and coloured with coffee spots, in two days was quite 

 white and clean. If the paper were now dried, it would not only 

 be very brittle, but would also rapidly become brown ; hence the 

 acid must be completely removed. The paper is immersed 

 in water, which is frequently renewed, until it only gives a very 

 feeble acid reaction with litmus. It is next placed in water to 

 which a few drops of solution of soda have been added, and then, 

 being spread on a piece of glass and placed in an inclined posi- 

 tion, is exposed to a thin stream of water for twenty-four hours. 

 After being allowed to stand till, nearly dry, it is carefully 

 removed and dried between blotting-paper. 



Gorup-Besanez found that ozone was not well adapted for 

 cleaning oil colours. 



Pohl has communicated* a research on the white gunpowder 

 invented by Augendre, which consists of prussiate of potash, 

 white sugar, and chlorate of potash. Pohl finds that the fol- 

 lowing mixture gave a very good burning powder : — 



Prussiate of potash 28 parts. 



Sugar . ' . . . 23 „ 



Chlorate of potash 49 „ 



100 

 which is very nearly in. the relation 



K^fy^HO + C^H^O'^SKOClO 5 . 

 Of the products formed by the combustion of this powder, it 



* Sitzungsberichte der Wiener Akademie, vol. xli. 



