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LIX. On the Purple Violet Flower, ami the different Shades 

 of Colour which may he extracted from it. By John 



MiCHAKL HauSSMANN*. 



Water is not the only menstruum proper for extracting 

 the colouring matter of plants, in order to make it adhere to 

 the alumine and the oxide of iron fixed on any particular 

 cloth. There are vegetables, such as the buglo&s {Anchusa 

 tinctoria), which onlv aivc up their colouring particles to 

 alcohol. I shall not hazard a definition of the nature of 

 the colouring substance of the bugloss ; it is so susceptible 

 of being decomposed by the continued action of heat, even 

 below that of boiling water, that, after having extracted it 

 by alcohol, it cannot be thickened or concentrated by eva- 

 poration, without being destroyed; so that it is impossible 

 to iiiake any further use of the spirituous part of the tincture 

 of biJgloss : 1 ascertained this by reducing a certain quantity 

 of it to one-fourth by distillation. The alcohol I obtained 

 from it appeared pure, and the residue was dirty, and im- 

 prop(M- for dyeing. I was to blame in not better exaiTiIning 

 it, in; order to see if it contained any thing oily or resinous j 

 my re'searches al that time had no other object than to pro- 

 cure t,he colouring parts of the bugloss, and I had reason to 

 be sa'tisfied with it. 



Bv mixing a sufficient quantity of the spirituous tincture 

 of briiiloss with six or eight parts of pure water in a copper 

 kettle, and by afterwards dyeing with it my skains of cotton 

 which were prepared for the red tincture of Adrianople, ac- 

 cordin/g to my own process, and as adopted by M. Chaptal, 

 I obtaitucd at the end of an hour, and by directing the fire 

 gradually until it produced a boiling heat, a beautiful colour 

 of pui pte violet. In order constantly to produce this colour 

 of the hvelicst hue, it is only necessary that the cotton should 

 not be ejpoiled by the preliminary preparations, and for this 

 reason the practice of galling should not be made use of; 

 the linseed oil I made use of for this preparation was boiled 

 with white l-ad, taking care not to burn it, as that would 

 have fioll'.d the cotton. 



• From Annates dc Chimk, torn. Ix. p. 288, 



The 



