526 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



cording to the shade desired. The feathers may also be 

 removed, and more blue be added, if it is found desirable. 

 They must be washed in a number of changes of water, to 

 the last of which some cream of tartar should be added. 

 25 (7, XIX., 1875, 150. 



, WHITENING WOOL WITHOUT SULPHUE. 



In whitening wool according to the following process, the 

 proportions given must be so modified, to suit the quality 

 of it, that the fibres do not become harsh and brittle ; the 

 latter evil may, however, also be avoided by placing the 

 wool, on its removal from the sulphuric-acid bath, in luke- 

 warm water, containing a few crystals of soda. The wool is 

 placed for an hour in a kettle containing, for 33 lbs., about 

 52 gallons of hot water, and \\ lbs. of carbonate of baryta. 

 It is then removed to a new hot bath, of the same volume, 

 containing about 3 pints of sulphuric acid, to which a few 

 drops of aniline-blue soluble in water may be added. 5 C, 

 XIX., 1875, 152. 



COLORING COPPER ALLOYS AND SILVER A DEEP BLACK. 



According to Paul Weiskopf, any alloy of copper, or sil- 

 ver alloyed with copper, may have a deep black, permanent 

 film, that will endure polishing with leather and oil, formed 

 upon it by rubbing it hard witli the tip of the thumb slight- 

 ly moistened with deliquesced bichloride of platinum. The 

 process may be considered inexpensive, in spite of the price 

 of the bichloride, since so little of it is required, and the ma- 

 nipulation is so simple. 14 C, CCXV., 1875, 470. 



PURIFICATION OF HYDROCARBONS EMPLOYED IN DRY OR 



CHEMICAL CLEANING. 



Dr. Vohl, of Cologne, contends that the purification, with 

 sulphuric acid, of benzol, etc., that has been employed for 

 cleaning garments, is not to be recommended, since sulphur- 

 ous acid is formed by the action of the organic matter, 

 and this is taken up by the hydrocarbon, and may injure 

 the color, and even the fibre of linen and cotton, in its sub- 

 sequent use, unless it is removed by an alkali. Besides, an 

 alkali, or alkaline carbonate, is the proper reagent for the 

 removal of the fatty acids that form a portion of the impuri- 



