Polytechnic Association Proceedings. 597 



a dischaege for aniline oolobs. 



A process important to printers using aniline colors has been 

 devised by Dangeville and Gutin. They substitute for the pow- 

 dered zinc, now generally used, a solution of permanganate of 

 potash in a slight excesss of dilute sulphuric acid, thickened with 

 kaolin, pipe clay, or gelatinous silicate. With this they print; 

 oxidation takes place; and the fabric is nearly colorless. The small 

 portion of oxide of manganese remaining is readily removed by a 

 weak bath of sulphurous acid. 



HYPOCHLORITE OF MAGNESIA IN BLEACHING. 



We have previously noticed the use of hypochlorite of magnesia 

 in place of hypochlorite of lime for bleaching purposes. The 

 principal advantage of the process is that the liberated magnesia 

 does not act on the tissue to be bleached. The best way of pre- 

 paring the hypochlorite of magnesia is to decompose sulphate of 

 magnesia with hypochlorite of lime. When the sulphate of mag- 

 nesia contains manganese, the liquid assumes a red color, and loses 

 its bleaching power. 



Mr. Keid said that bleaching under a pressure of one hundred and 

 sixty pounds per square inch has been found to be very suc<;essful. 

 It is calculated that Messrs. Sprague & Co., extensive cotton manu- 

 facturers, of Rhode Island, will effect a saving of $200,000 per 

 annum by this improvement, in which the bleaching is completed 

 in six hours. 



OXIDATION BY MEANS OF CHARCOAL. 



A communication was lately read at the London Chemical 

 Society concerning experiments made with recently burned box- 

 wood charcoal. It was first placed in pure oxygen gas, and, aft^r 

 being saturated, into other gases and vapors, and the absorption, 

 as well as the resulting products, were noted. Moist "sulphui'ous 

 acid and sulphuretted hydrogen were changed to sulphuric acid; 

 common alcohol to acetic acid; amylic alcohol to valerianic acid; 

 but the author asserted that ammonia does not undergo oxidation 

 in the pores of charcoal. 



THE SILKWORM IN AUSTRIA. 



M. de Bretton, a sericulturist, states, that the Chinese silkworm 

 has become perfectly acclimatized in Austria, and it is now in its 

 fourth generation there as well as in France. Last year he obtained 

 4,000 cocoons of this species, which yielded nearly 300,000 eggs, 



