208 ANNUAL OF SCIENTIFIC DISCOVERT. 



be used in printing paper or textile fabrics. It is possible, how- 

 ever, in the wet way, to produce a green oxide of chromium not 

 devoid of beauty. MM. Casthela and Leune prepare what the}' 

 style imperial green, by slowly precipitating salts of chromium by 

 treating them with hydrated metallic oxides, carbonates, or sul- 

 phides; the action proceeds gradually, and the color of the hy- 

 drated oxide precipitated is a deep emeiald green. Practically 

 the reagents cmi)loyed are gelatinous alumina and the oxides, 

 carbonates, and sulphides of zinc and iron. Tlie color of the green 

 precipitate may be modified by the use of reagents forming with 

 the acid of the salt of chromium insoluble salts. — Mon. Sci. 



BLEACHING WOOD-PULP. 



The diflSculties encountered in the bleaching of wood-pulp are, 

 (1) that chloride of lime, however little in excess, has a tendency 

 to produce a yellow tint ; (2) that strong acids turn the paste red 

 under the action of the sun, or after some time without .sun- 

 light in the presence of moisture; (3) that the slightest trace of 

 iron is sufficient to blacken the paste in a short time. 



M. Orioli obviates these objectionable results by the use of 

 oxalic acid, the energetic action of which on vegetable coloring 

 matters is well known. For 100 kilos, of wood-i)ulp he employs 

 800 kilo.s. of oxalic acid, which senes the double purpose of bleach- 

 ing the coloring matters already oxidized, and of neutralizing the 

 alkaline principles favorable to oxidation ; two kilos, of sulphate 

 of alumina, perfectly free from iron, are also added. This sulphate 

 of alumina does not bleach of itself, but forms with the coloring mat- 

 ter of the wood a nearly colorless lake, which, remaining in the 

 pulp, enables the brilliancy of the product to be heightened. — 

 Chem. News, Jan., 18G9. 



BLEACHING PAPER-PULP. 



M. Gauny proposes to bleach paper-pulp by means of bichro- 

 mate of potassium. For 100 kilos, of i)ulp (supposed to be dry) he 

 uses 50 kilos, of bichromate and 150 kilos, of hydrochloric acid, 

 mixed with a sufficient quantity of water to make the pulp float. 

 Alter 12 hours' standing the chloride of chromium is washed out 

 by means of clean water, and the pulp treated with a small quan- 

 tity of bleaching powder to make it thoroughly white. The 

 chloride of chromium is precipitated with excess of lime, and this 

 mixture calcined in a revcrberatory furnace, where it is converted 

 into chromate of calcium. 



NEW METHOD OF BLEACHING FEATHERS. . 



This process is a new one, and by it even black feathers of 

 ostriches and other birds may be bleached. The feathers are 



