SOME COXTfilBTJTIONS TO PLANT-CHEMISTRT. 171 



Cotton in its natural state always resists wetting to some extent, 

 and has a very faint yellowish hue. By the following treatment it is 

 altered in these particulars, absorbing water directly it is poured 

 upon the fibres, and showing a dazzling whiteness when dry, and a 

 pale bluish tint when wet. The treatment consists in first soaking 

 the picked cotton in very weak warm ammonia water for 24 hours, 

 then washing it in abundance of distilled water, and lastly leaving 

 it in contact with weak chlorine water for another day. A final wash- 

 ing and the drying of the purified material in the air complete the 

 process. The cotton thus prepared makes excellent gun-cotton and 

 collodion. 



6. Phormium tenax. — If cotton is nearly pure cellulose we have in 

 the fibre of Phormium leaves a very good example of a mixture of cel- 

 lulose and of the substances to which the convenient term lignose may 

 be applied. I hope some day to enter fully into the methods of recog- 

 nising and separating these substances. Indeed, the two reports on 

 the chemistry of Phormium tenax which I have addressed to the Plax 

 Commission of New Zealand contain many points of interest in con- 

 nection with this subject. These reports will shortly be published in 

 the form of an abstract, but in the meantime I may select from them 

 the following curious observations as to the effect of water at a high 

 temperature on tissues containing lignose, and on the indifference of 

 cellulose to such treatment. When pure cellulose, prepared from cotton 

 as just described, was boiled for twelve hours with distilled water 

 it gave up no appreciable amount of organic matter to the water, 

 which did not acquire an acid reaction. Even in a sealed tube, at a 

 temperature maintained at 150° C. for four hours, water was almost 

 without effect on cotton. Eut with Phormium fibre a small [quantity, 

 about 4 per cent., of an acid yellow extract was obtained even by 

 simple ebullition with water at 100° C. ; while at 150° to 160° C. 

 water causes so great a change in the material that it dissolves 

 in quantities amounting in different specimens to 19, 24*4, and 

 even 33-3 per cent, of the dry fibre taken. The nature of the 

 products formed has been in great measure investigated, a kind of 

 sugar and an acid body occurring amongst them. But the point to 

 which I wish now to direct attention is the test which water at high 

 temperature affords of the presence or absence of the so-called 

 secondary deposits. We know that lignose is coloured yellow, brown, 

 or red by strong nitric acid, and that, in the purest state in which it 

 has yet been separated, it is richer than cellulose in carbon by about 

 10 per cent. But the employment of water under pressure and at 



