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FURTHER NOTES ON 

 THE CHEMISTRY OF THE ROSACEA 



P. Q. KEEGAN, LL.H 

 / *atierda /r f Ulleswa ter. 



As my paper in the January number of this journal (1S95,. 

 page 23) has not perhaps been fully understood by some readers, 

 I propose here to add a few explanatory remarks relative to the 

 subject matter thereof, followed by a short summary of conclusions. 

 The main reason for investigating by chemical analysis the rosacean 

 plants was as stated, viz., ' to trace a connection between the vivid 

 and powerful pigments exhibited by the flowers, leaves, etc., and the 

 products of metabolism, such as can be referred to the benzene or 

 other series of hydrocarbons noted for their colour-producing 

 properties.' Everyone knows that carbon is the essential element 

 of organic nature, i.e., animals and plants are almost entirely 

 constructed of compounds of carbon. Now the first and most 

 fundamental class of carbon compounds are the hydrocarbons or 



the combinations of carbon with hydrogen alone, and of these 

 a series of six or seven in number are the most important. Everyone 

 has heard of or seen the magnificent aniline dyes manufactured from 

 coal-tar, and the question naturally arises, to what series of hydro- 

 carbons can these splendid colourations be referred? The answer 

 is, that nearly all organic dye-stuffs are derived from what have been 

 termed respectively the benzene, naphthalene, anthracene, or 

 quinolene series of hydrocarbons. Now, let us direct our attention 

 to the fields, woods, and gardens. Are the brilliant and beautiful 

 pigments of Roses, Bluebells, Hollyhocks, etc., in any way related 

 as respects their origin, etc., to the superb scarlets, blues, yellows, 

 etc., which in these latter days fascinate us in the ball-room or at the 

 ballet or pantomime? Would it not be supremely interesting if 

 someone were to discover that these coal-tar colours put us as it 

 were in possession of the very colours by which nature adorns the 

 flowers? In the year 1869, Dr. Phipson averred that l in numerous 

 cases the general chemical properties and spectral characters of the 

 flower colours are identical with those of the ^coal-tar colours 

 {Jeuni. C/iem. Soi\, 1869). This statement has not bean borne out, 

 inasmuch as it is certain that most artificial dye-stuffs have no 

 analogue in plants or animals. Nevertheless, chemical researches 

 have established the fact that the colours of flowers are mainly 

 derived from the benzene series of hydrocarbons, which likewise, as 

 aforesaid, gives origin to some of the most telling and brilliant 



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