Church. — On the Chemistry of Phormium tenax. 263 



centage of sugar was deduced from the examination of the matters thus 

 removed from the tissues of the leaves. The analysis of the solution thus 

 prepared led to the following numbers, as representing the proportion of sugar 

 in the leaves of the Phormium : — 



Calculated as Cane Sugar. 



In the fresh leaves ... ... ... 5*45 percent. 



In the diy leaves ... ... ... 19*20 „ 



It may be concluded that these numbers are rather too high, owing to the 



conversion of some of the gum and starch of the plant into sugar- bj means of 



the treatment to wliich the aqueous extract had been submitted. But though 



5|^ per cent, of sugar is probably an extravagant estimate, I am inclined to 



think that it is not more than 1 per cent, in excess of the truth; so far, at 



least, as the richness of English grown leaves is concerned. 



D. — The Bitter Principle. 



A notion appears to prevail that the bitter principle of the Phormium 

 tenax is a coloured substance : this is quite incorrect. Doubtless when an 

 aqueous or alcoholic extract of the leaf is made, the bitter principle, thus 

 dissolved out, is accompanied by colouring matters, but these matters merely 

 accompany the true bitter principle. If reference be made to the report, 

 p. xix., 1871, of the Flax Commissioners,* it will be seen that the bitter 

 principle is therein spoken of as coloured — " purity of colour can only be 

 obtained by thoroughly washing out the hitter principle from the plant." 

 Again, in the appendix to the above-named report, at page 84, Capt. Hutton 

 states, "The bitter principle might perhaps be used as a dye or stain for 

 wood," etc. The mixed nature of the substances extracted from the plant by 

 water, and the subsequent changes which some of the substances undergo in 

 the presence of air and moisture, account for the mistake which I have pointed 

 out. As I shall have again to refer to the colouring matters of Phormium in 

 the next section, I will now merely describe the method by which the bitter 

 principle was obtained in a state approaching purity. 



The selected leaves were cut into small pieces and then carefully dried. 

 About a pound of the dry matter was then exhausted with boUing alcohol. 

 The hot alcoholic extract (or rather extracts) was then filtered, some wax (see 

 § 1 B) being deposited on the filter during the passage of the liquid through 

 it. The filtered liquid was then evaporated, first in a retort, then at 100° 

 centigrade, and finally in vacuo. The residue corresponded to 19 '6 per cent, 

 of the dried leaves taken. It was, of course, free from starch and gum, but 

 contained many other substances besides the bitter principle. In order to 

 isolate this principle the following plan was adopted : — The last-described 

 residue was boiled in abundance of water, and then the liquor was filtered. 



* App. to Journ. H. of K,., 1871, G. No. 4. 



