442 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



pounds of cold water are then added, and the whole heated 

 and boiled together for a quarter of an hour, by which means 

 the surplus of ammonia is expelled. The paste thus obtained 

 is semi-transparent, and fit for use. It gives a fine gloss not 

 only to woven fabrics, but to paper, etc. It is very service- 

 able for purposes of the laundry, since it stiffens well, and 

 quickly produces the desired gloss. Part of the gluten is 

 made soluble by the action of the ammonia, and thus the 

 paste, when dry, is more pliable than that of pure starch; it 

 is thus especially adapted to the use of book-binders, paper- 

 box makers, etc. 6 C\ 1871, 126. 



USE OF RICE STARCH IN FINISHING. 



It is said that many German manufacturers are greatly in- 

 terested at the present time in the subject of rice starch. 

 They have employed it to advantage in finishing goods, and 

 consider it of great value on account of its entire freedom 

 from sandj and as being without the injurious results some- 

 times attendant upon the use of wheat starch, from its be- 

 coming sticky. The only drawback seems to be the greater 

 cost of the rice starch, although the effect produced by 100 

 lbs. is equal to that of 115 lbs. of wheat starch. Notwith- 

 standing this difference, however, the rice starch is still pre- 

 ferred on account of its intrinsic value for some kinds of 

 goods. 5 C\ 1871, 112. 



GRAEFE'S METHOD OF DYEING WITH PRUSSIAN BLUE. 



A process of dyeing with Prussian blue, commonly called 

 potash blue, suggested by Dr. G. A. Graefe, is considered a 

 valuable improvement in the arts. In this a sufficient quan- 

 tity of oxalate of ammonia is added to a solution of the ni- 

 trate or some other salt of iron, and when the prussiate of 

 potash is added, any precipitate is to be immediately redis- 

 solved by stirring. The yarn or fabric to be colored is first 

 soaked for some hours in this compound solution, and trans- 

 ferred without wringing into an acid bath containing some 

 chloride of tin. The blue color immediately appears, and the 

 subsequent treatment is the same as that in ordinary use. 

 When fabrics have been impregnated with the above triple 

 solution, and are printed with an acid mixture containing 

 cloride of tin, the pattern appears blue upon white grounds 



