51 S ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of preparing the compound is as follows : In one of two 

 pans, each of a capacity of about five gallons, place twenty 

 pounds of sulphate of alumina cut in thin slices; into the 

 other pour eight pounds of oleic acid, and about a gallon and 

 a half of alcohol. Stir in order to properly mix them, and 

 then pour gradually the contents of the second pan into the 

 first, stirring all the time with a wooden pallet for about 

 twenty minutes. When the mixture is complete, allow it to 

 settle for about twenty-four hours. The alcohol and the oleic 

 acid, which floats on the top, can be poured off, and the pre- 

 cipitate is placed in a felt filter, and submitted to a strong 

 pressure in order to obtain a solid cake. This cake is re- 

 moved and dried in a moderately hot stove, and afterward re- 

 duced to powder. This powder is prepared for use for w T oolen 

 fabrics by mixing and dissolving one pound in about twenty 

 gallons of water. For silk, linen, and other fabrics, one and a 

 half pounds of the powder will be required for every twenty 

 gallons of water. The solutions are to be passed through a 

 sieve before dipping the fabrics, which should be completely 

 saturated and afterward removed and dried, w r hen, it is as- 

 serted, they will be found to be impervious to water, but not 

 to air. 18 A, September 29, 1871, 31. 



RISE IX THE PRICE OF BICHROMATE OF POTASH. 



The attention of dyers has been called to the recent increase 

 in the cost of bichromate of potash, a substance now so much 

 used for photographing and other technical purposes. We 

 are informed that the price hitherto paid was abnormally low, 

 compared with the cost of production, and it is stated that 

 this was due to the competition between two Scottish firms 

 engaged in its manufacture, who in their rivalry brought the 

 price down to about ten cents a pound. Recently the de- 

 mand has been greater than these two firms could meet, and 

 the difficulties between them having been compromised, the 

 price has already risen to double the sum mentioned, with a 

 probability of being further increased. In this contingency, 

 and in view of the great need of it at cheap rates, the estab- 

 lishment of manufactories in Germany is advocated, and it is 

 thought that the chrome ores of Galicia can be used to good 

 advantage in this connection. As the consumption in Berlin 

 alone amounts to three hundred thousand pounds annually, 



