288 ANNUAL OF SCIENTIFIC DISCOVERY. 



COLORING MATTER OF FLOWERS. 



This question has been studied by several chemists, and still is, beyond 

 doubt, one of the most obscure subjects in vegetable chemistry. Botanists 

 have long admitted that flowers owe their color to two coloring princi- 

 ples a blue, called cyanic, and a yellow, called xanthic. For some time 

 the blue color of blue flowers was attributed to presence of indigo ; but 

 Chevreul showed that this blue is always reddened by acids, which fact 

 sets the indigo theory aside. 



MM. Fremy and Cloez have isoluted the blue principle, and they call it 

 cyanine. To obtain it, they treat with boiling alcohol the petals of the 

 violet, or iris, until the flower is colorless and the liquid takes a fine blue 

 tint. The tint disappears soon, but reappears on evaporating the alcohol 

 in the air ; on pouring water into the product of this evaporation, a resin- 

 ous substance separates ; the coloring matter remains in solution, and may 

 be precipitated by acetate of lead ; the precipitate is green ; it is washed 

 with a large amount of water, and treated with sulphuretted hydrogen, 

 which removes the lead, and leaves the cyanine in solution. It is gently 

 evaporated in a w r ater-bath, absolute alcohol is added, and then the cyanine 

 is precipitated in bluish flocks by ether. This coloring matter is un- 

 crystallizable ; acids turn it red, alkalies green ; it combines with lime, 

 baryta, &c. ; sulphurous, phosphorus, and other acids, discolor it ; it re- 

 sumes its blue color through the presence of the oxygen of the air. 



The coloring matter of roses, peonies, some dahlias, &c., is a modifica- 

 tion of cyanine ; the vegetable juices have an acid reaction, (which 

 changes the blue cyanine to red ;) while the juices of blue flowers are neu- 

 tral. In the presence of alkalies, the rose color becomes, first blue, and 

 then green. 



The yellow coloring matter has no relation to cyanine. There are two 

 different substances one insoluble in water, xanthine ; the other very 

 soluble, xantheine ; the former is analogous to the resins, and, along with 

 cyanine, it produces in flowers an orange color, a scarlet, and a red. The 

 xantheine combines easily with oxides ; alkalies change it to brown of a 

 very rich color and of considerable strength ; but acids cause the brown 

 color to disappear. These are the three principal coloring ingredients of 

 flowers. , M. Filhol, who has also studied this siibject, confirms the results 

 of MM. Frcmy and Cloez. He has, however, found that these coloring 

 matters may be disguised, or even destroyed, by mixture with the juices 

 of white flowers. 



M. Pepin, " Chef de Cultures" at the Jardin des Plantes, of Paris, has 

 made some curious observations on the change of color which culture pro- 

 duces in flowers. He has found that cultivated annuals experience a 

 change of tint more promptly than perennial plants, for each year they 

 are renewed through the seeds. Such a change is, however, sometimes 

 produced in biennials and perennials, and rarely ever in ligneous species. 



