486 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



near to the object to be traced, and the one end of the lever 

 is moved by the right hand so that the other end continually 

 touches the object, a pencil fixed in the lever will trace a 

 diminished profile of the object on paper. This can after- 

 ward be enlarged to the full size by means of the same in- 

 strument. 14 (7, CCXVL, 204. 



A printer's ink readily removable from waste paper. 



The following process for the preparation of a printer's ink 

 that can be far more readily removed from waste paper than 

 ordinary printer's ink has been patented by Kirscher & Ebner. 

 Iron is dissolved in some acid sulphuric, hydrochloric, acetic, 

 etc., will answer and half of the solution is oxidized with 

 nitric acid and added to the other half, and the oxide pre- 

 cipitated from the mixture by means of soda or potash. The 

 precipitate is thoroughly washed and treated with equal parts 

 of solutions of tannic and gallic acids, and the bluish-black 

 or pure black pigment formed is thoroughly washed and dried 

 and mixed with linseed-oil varnish, and can then be imme- 

 diately used for printing from type, copper, wood, steel, or 

 stone. Waste paper printed with it can be bleached by di- 

 gesting it for twenty-four hours in a lukewarm bath of pure 

 water and ten per cent, of caustic potasli or soda, and then 

 grinding it well in the rag-engine, and throwing the pulp upon 

 cloth and allowing: it to drain. It is then to be washed with 

 pure water containing ten per cent, of hydrochloric, acetic, 

 or oxalic acid, or of binoxalate of potassa, and allowed to 

 digest for twenty-four hours, and may then be worked up 

 into paper, or it can be dried, and used as a substitute in the 

 manufacture of finer paper. 5 C, XXXIX., 1875, 312. 



FOR TAKING TRACINGS. 



The following process has lately been suggested : One part 

 by volume of castor-oil should be dissolved in two or three 

 volumes of alcohol, and this solution applied to the i^aper 

 with a brush. The spirit soon evaporates, leaving the paper 

 transparent and ready for use. A tracing in pencil may then 

 readily be made, and when finished the paper is immersed 

 in alcohol, which dissolves out the oil, restoring the sheet to 

 its original condition. The drawing may afterward be com- 

 pleted in Indian ink or in colors. 



