448 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



BLEACHING OF WOOD PULP. 



According to Dr. Winkler, neither chlorine, bromine, nor 

 any substance the activity of which is due to oxidation, will 

 answer the purpose of bleaching wood pulp for paper making, 

 the result being, in all cases, the production of a decidedly 

 yellow, and sometimes even a brown tinge. Sulphurous acid 

 Avas also found to be not entirely satisfactory, while the at- 

 tempt at destruction of the natural coloring matters by means 

 of fermentation proved to be of no practical value. There 

 seems, therefore, to be room for the discovery of some addi- 

 tional mode of manipulation in order to effect the desired re- 

 sult. 16 A, January, 1870, 108. 



Fischer's method of bleaching straw. 



A method of bleaching straw, which is said to secure a re- 

 sult much superior to that of the ordinary processes, while 

 not affecting the firmness of the material in the slightest de- 

 gree, consists in placing the straw in question in tubs of 

 white wood, and pouring hot water upon it, and allowing it 

 to remain twenty-four hours, after which the water is to be 

 poured off. The straw is then to be boiled for three hours in 

 a copper vessel, in a lye prepared by adding one pound of 

 soda to one quart of water, and from time to time replacing 

 the water which escapes in steam without interrupting the 

 boiling. The solution is then allowed to cool, and the straw 

 again placed in the tub and covered with cold water, and, 

 pouring this off after it has become of a yellow color, then 

 fresh water is to be used in the same manner several times 

 until the water seems clear. The straw is a2;ain to be boiled 

 an hour in a solution half as strong as the original one, and 

 then removed, and boiling water poured over it in a tub, 

 which is allowed to cool, and cold water again poured upon 

 it. This operation is to be repeated from time to time for 

 three days ; after this, the straw is to be covered with a so- 

 lution of chloride of lime or chloride of sodium, the vessel 

 closed, and left for twenty-four to thirty-six hours, or longer, 

 until the straw appears completely bleached. The liquid 

 need not be thrown away, but can be used for the earlier pro- 

 cesses of the preparation of other quantities of straw. The 

 straw thus prepared acquires a peculiar and rather persistent 



