Church. — On the Chemistry of Phormium tenax. 265 



matter originates in a peculiar pi'inciple, of an acid character, which, not only 

 exists in the healthy and vigorous leaves of this plant, but which may actually 

 be developed by an alteration of one of the constituents of the fibre itself. I 

 refer to the substance mentioned in my former report under the name 

 " pyrocatechin " (see page 18 of that report). A large quantity of this 

 substance, which has the chemical formula Ce He O2, appears to be formed, as I 

 previously concluded, from the mere heating of the Phormium fibre with water 

 to a temperature of 150° centigrade, when about one-fifth of the weight of the 

 dressed fibre taken is dissolved and transformed into soluble matter. My 

 conclusions on this point have been lately confirmed by another chemist, 

 F. Hoppe-Seyler, who has made pyrocatechin by heating pure linen filter-paper 

 to a temperature of 210° centigrade, for four to six hours, with water. But 

 the action on the Phormium fibre, though requiring a much lower temperature, 

 is far more extensive than is the case with flax, with hemp, or even with 

 Manilla. We have, therefore, in the natural occurrence of pyrocatechin in the 

 Phormiumj leaf, and in its easy production by the action of heat and moisture 

 upon the very substance of the fibre itself, a mode of accounting for some at all 

 events of the discolourations and alterations to which the Phormium fibre is 

 liable under some modes of treatment. For it must be remembered that 

 pyrocatechin gives rise to a variety of colour-reactions under the influence of 

 chemical re-agents, etc. Of this matter I shall, however, speak in the next 

 heading of the present section. 



F. — Organic Acids of the Phormium Leaf 



In describing the mode adopted of separating the bitter principle of the 

 Phormium leaf, I mentioned the lead subacetate precipitate, formed from the 

 extract of the plant, as containing the lead compounds of the organic acids 

 present. When this lead precipitate has been washed with water and decom- 

 posed with hydro-sulphuric acid, it yields a mixture of several acid substances. 

 From the small quantity obtained of these bodies, and the difficulty of 

 separating them, I can give but very slight indications as to the acids of the 

 Phormium plant. These appear to be oxalic and citric acids in small propor- 

 tions, and pyrocatechin in greater amount. This latter substance has been 

 already alluded to under the heading E. It has many of the characters of an 

 acid. Its occurrence in the extractive matters of Phormium tenax was 

 recognized by — 



1. The formation of a precipitate with neutral lead acetate, and the 



solubility of this precipitate in acetic acid. 



2. The volatility and odour of the substance. 



3. The darkening of the solution by the addition of lime-water and exposure 



to the air. 



Rl 



