36 Tannin in tJic Fruit of the Pcrsimmon [Sept. 



Tlie foregoing considerations lead us to the conclusion that the 

 task remaining is to separate the tannin and the associated colloid, 

 which, I have argued, combine vvith each other dnring ripening. 

 The ease with which the ripe tannin-cells may be separated from 

 the softened ptilp, as Vinson (1907)^^ found to be the case in 

 the date, enables us to get quantities of the tannin-masses for 

 chemical investigation. I have found (1911) that weak mineral 

 acids cause the synchronous Solution of the tannin and of the 

 associated colloid, but I obtained a few cells which showed a rem- 

 nant of the latter which did not give a tannin reaction. Since then 

 I have found that, by using very strong nitric acid and by careful 

 boiling for some minutes, the end-point being indicated by a swelling 

 of the tannin-masses, the tannin may be completely extracted,^*^ 

 without attacking the associated colloid appreciably. This colloid 

 is finally hydrolysed. Concentrated sulfuric acid gives a similar 

 result, with some minor dififerences of no immediate moment.^^ 



This experience seems to mean that it has been possible to split 

 off the tannin before marked hydrolysis of the associated colloid 

 occurs. And it is now possible to investigate this substance with 

 a hope of throwing light on the true nature of the associated 

 colloid. Some preliminary work indicates that it is a cellulose 

 mucilage, a view supported by its behavior toward mineral acids. 

 Such a substance, in superficial appearance, occurs also in the non- 

 tanniferous pulp-cells; but whether this is identical with that in 

 the tannin-cells remains to be seen. That in the pulp-cells is not 

 miscible with water, contracts (becoming highly refringent) upon 

 treatment with glycerol, and is broken up into globules by alcohol. 

 Upon addition of water, the cells burst, as do the tannin-cells, 



^* Vinson who speaks of the tannin-mass as insoluble tannin states that it 

 does not give the tannin reaction unless the dates are fresh, " even after boiling 

 with acids" (1907, p. 261). I have, however, found it quite easy to get the 

 reaction even in market dates. 



^ Vinson apparently failed to see the significance of his Observation, em- 

 bodied in the previous footnote, that " after boiHng with acids " tannin cells 

 from the date fail to give a reaction. 



^ For f urther details concerning the behavior of the associated colloid toward 

 chemical reagents see Lloyd, F. E. : Ueber den Zusammenhang zwischen Gerbstoff 

 und einem anderen Kolloid in reifenden Früchten, insbesondere Phoenix, Achras 

 und Diospyros. Zeitschrift für Chemie und Industrie der Kolloide, 9 : 65-73. 

 1911. 



