8 



Alisillill. An acrid and bitter substance, occurring in the 

 roots of Alisma Plantago, but only obtained in the extractive 

 form, and has as yet not been closely examined. 



Alizarin = C20 Hg Oe + 4 HO. In the root of Eubia tinc- 

 torum. Boil the pulverised root (madder) with water, precipitate 

 the decoction with sulphuric acid, and boil the well-washed pre- 

 cipitate with chloride of aluminium, in order to dissolve the dyeing 

 substances. The solution, when mixed with a little hydrochloric 

 acid, separates red flocks consisting of Alizarin, purpurin and 

 resin. These flocks have to be dissolved in alcohol, or in diluted 

 liquor of ammonia under addition of ' freshly precipitated alumina, 

 which combines with the dyeing matters. This compound has to 

 be boiled with concentrated solution of carbonate of soda, whereby 

 purpurin is dissolved with deep-red colour, while Alizarin-alumina 

 remains in the residue. The latter has to be freed from resinous 

 matter by washing with warm ether, and is then decomposed by 

 boiling with diluted hydrochloric acid. The remaining Alizarin 

 has to be recrystallised in alcohol. It appears in long translucent, 

 dark-yellow prisms of great lustre, of neutral reaction, and of 

 bitter taste; loses the water at 100° to 120", turns opaque, darker 

 red, fuses afterwards, and sublimates at 215° in orange-red 

 needles; dissolves little in water, with purple colour in alkalies, 

 with blood-red colour in concentrated sulphuric acid, and is precipi- 

 table by water without change, with red-yellow colour in sulphide 

 of carbon, and with gold colour in alcohol and in ether. 



[From the tubers of various Australian Droserae a substance 

 has been obtained, wliich in physical properties closely resembles, 

 and probably is identical with. Alizarin. — Baron von Mueller 

 and Rummel.] 



Alkaloids. Compounds of carbon, hydrogen and nitrogen, 

 with or without oxygen, mostly of alkaline reaction, and able to 

 form salts with acids. Considering the short time (about fifty 

 years), which has elapsed since their existence has been discovered, 

 their number is rather considerable, and becomes greater con- 

 tinually, though only the minor portion of the plants as yet 

 treated for such have given positive results, perhaj^s because either 

 too little raw material has been employed, the quantity of alka- 

 loids in vegetables being comparatively small, or because the 

 proper method has not been adopted, or was not known, as is 

 partly the case even at present. Investigations in this branch of 

 phyto-chemistry are nevertheless so far progressing, that I may 

 venture some remarks regarding the approximate number and 

 distribution of alkaloids. 



The classification of plants into natural groups satisfies not only 

 the botanist to a high degi-ee, but also the chemist, for, just as the 

 former comprises all the plants that show a certain harmony in 



