534 THE STINGING PROPERTY OF THE GIANT NETTLE-TREE, 



pose the salts and displace the volatile acids; the latter being 

 free are then driven off on boiling. 



The aqueous solution after evaporation was extracted with 

 alcohol, and this left a large amount of insoluble matter which 

 was reserved. The alcohol was then distilled off, the residue 

 dissolved in water and extracted with immiscible solvents. The 

 latter on evaporation left a small yellow amorphous residue. 

 This was purified and examined. It contained no nitrogen, 

 reduced Fehling's solution, possessed a strong pungent and bitter 

 taste, blistered the tongue, and was soluble in hot water, giving 

 a yellow, acid solution. The latter when neutralised with calcium 

 carbonate became strongly fluorescent. On standing for some 

 time the neutral solution became acid by dissociation. It gave 

 no osazone, proving the absence of glucose. Fumes of formic 

 and acetic acids were evolved on boiling, and when these were 

 completely driven off Fehling's solution was no longer reduced. 

 This result shows the absence of glucosides. The reactions of 

 alkaloids also gave negative results, and the residue was proved 

 to consist mainly of a yellow colouring matter. 



Since the absence of organic base is thus definitely proved, it 

 only now remains to be shown whether the acids are fixed with 

 metals. The residue insoluble in alcohol, which was reserved in 

 the previous operation, was purified and examined. It consisted 

 almost entirely of calcium, magnesium, with traces of potassium 

 and sodium, and combined with formic, acetic and sulphuric 

 acids. 



Systematic Proximate Analysis of the Leaves. 



(a) Moisture. — A sample of the fresh leaves was dried in the 

 air at ordinary temperature, and lost 76 - 65 % of its weight. 



(b) On further drying at 110°C. in the air oven, 3 - ll % was 

 driven off, which is represented by water and volatile acids. 



(c) Ash. — The dried residue was incinerated in a muffle furnace 

 at incipient redness; the weight of ash obtained was 3-6%, or 

 15-42% on the air-dried leaves. The chief constituents of the 

 ash were then approximately ascertained: — 



