144 SHEET FABRICS. [ V. 



Another ink is made by adding a very small quantity of 

 blue vitriol to a solution of logwood-extract. This is apt to 

 precipitate. 



Soluble Prussian-blue {a Blue and Black Indelible Ink). — 

 Dissolve in a solution of iodide of potassium as much more 

 iodine as it contains, and pour this solution into one of yellow 

 prussiate of potash, containing as much of the solid prussiate 

 as the whole amount of iodine. Soluble Prussian-blue pre- 

 cipitates and iodide of potassium remains in solution. After 

 filtering, the precipitate is dissolved in water, and forms a 

 blue ink, containing no free acid, and therefore adapted to 

 steel-pens. If the soluble blue be added to common black 

 ink (from galls), the result is a black ink which cannot be 

 removed from paper without destroying it. 



Indelible Ink. — To remove spots of indelible ink, T. and H. 

 Smith propose moistening the spots for a few moments with 

 moist chloride of lime, which forms chloride of silver, and 

 then dissolving the latter by caustic ammonia. It may be 

 sometimes necessary to repeat the operation. (Chem. Gaz. 

 Sept. 1847.) Cyanide of potassium may also be employed. 



Printing-ink. — Pratt's patent consists in the use of rosin- 

 oil, instead of linseed oil, with rosin, yellow soap, &c., in the 

 manufacture of printing-ink. 



2. Sheet Fabrics and Solid Tissues. 



Among these are paper, leather, horn, caoutchouc, &c., of 

 which caoutchouc and guttapercha, being new, and presenting 

 remarkable properties, have been most rapidly advanced of 

 all others, during the past few years. 



Paper. — Amos and Clark claim improvements in the ma- 

 nufacture of paper, whereby, 1. The bluing material is more 

 uniformly distributed so as to equalize the tint on both sides 

 of the paper ; 2. The pulp is more expeditiously sifted ; 

 3. The paper is better dried on the cylinders ; 4. The paper is 

 glazed by means of a traversing horizontal table with two or 

 more pairs of rollers. (Lend. Journ. xxxvii. Aug.) 



