494 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



solution, and pass it (best after allowing it to dry) through 

 a warm, very dilute solution of sulphuric acid, and it will 

 immediately assume a beautiful blue color, and needs only 

 to be washed in water. The sulphuric acid may be so di- 

 luted that it has scarcely a perceptible sour taste. 5 C, XL., 

 32. 



FIXING PKUSSIAN BLUE ON FABKICS. 



Scheurer, of Berlin, recommends for a dark shade fifty parts 

 of tartaric acid, one hundred and ninety parts of ammonia, 

 one hundred and ten parts of dry powdered Prussian blue, 

 and one hundred and fifty parts of water, with the employ- 

 ment of a gentle heat to hasten solution. In dyeing, the 

 material is passed through this solution, and then, after dry- 

 ing, through an acid. For printing, an equal weight of 

 thick tragacanth water is added to it, and the material, after 

 printing and drying, is also passed through an acid. After 

 the dyeing, or printing, a very deep violet color develops 

 in drying, which immediately changes to blue on contact 

 with the acid, and is almost completely fixed, remarkably 

 little being lost in washing. 25 C, XXIV., 7. 



FORMxiTION OF PUEPUIIINE FEOM ALIZARINE. 



Lalande has succeeded in preparing purpurine from aliza- 

 rine, which was perfectly free from the latter, after treating 

 it with oxidizins: assents under different conditions. One 

 part of dry pulverized alizarine, and one of dry arsenic acid, 

 or of peroxide of manganese, were added to eight to ten 

 parts of concentrated sulphuric acid, and the temperature 

 was gradually raised to 302 to 320, until a drop of the 

 mixture placed in slightly alkaline water produced the red 

 coloration of purpurine. The mass was then treated with a 

 large quantity of water and the precipitate washed with cold 

 water, dissolved in a sufficient quantity of a saturated solu- 

 tion of alum, and re-precipitated by an acid. It was com- 

 pletely purified by treatment with alum again and crystalli- 

 zation out of superheated water. 5 C, XL., 23. 



DOVE-COLOE, ON RAW WOOL. 



For one hundred pounds of wool, dissolve two pounds of 

 alum and one pound of argol in a hot bath, and cool to 158; 



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