Eucalyptus xnlularis containing 18*32°/° water = 838 



E. macrorrhyncha 





n 



18*06f , 



, = 835 



E. eugenioides 





n 



18*10°/° , 



, =811 



E. paniculata 





n 



20*25°/° , 



, = 423 



n 





11 



22-78 /' , 



, =412 



E. siderophloia 





11 



20*28°/° , 



, = 459 



E. sideroxylon 





11 



19*46°/° , 



, = 459 



E. crebra 





11 



18-77°/o , 



= 470 



Glucoside 





11 



11-75°/' , 



, = 423 



It is thus seen that 



the 



kinos of the " Ironbarks " have 



only about half the astrini 



*ency 



value of the 



other three 



kinos, although the tan nil] 



l appears to be the 



same in all 



of them. 











Tanning value by hide poivder. — The ready and entire 

 precipitation of the tannin of the glucosidal kinos by gelatin, 

 makes it difficult to understand why it is that the tannin 

 is not more readily absorbed by hide. The technical diffi- 

 culty of the sluggishness of " Ironbark " liquors has long 

 been known, but no scientific explanation has been advanced 

 to account for this peculiarity. The reason is now apparent 

 that it is the glucosidal nature of the " Ironbark " kinos 

 (the kino being the principal tanning agent) that causes 

 the unsatisfactory behaviour of this tanning material. To 

 overcome this difficulty and thus make the tannin of the 

 bark of E. sideroxylon, for instance, available for rapid 

 absorption by hide, it will be necessary to devise some 

 method of hydrolising the glucoside while in the pits, per- 

 haps by means of an enzyme or corresponding substance. 



The following results were obtained with the kino of E. 

 paniculata, and from which it is apparent that when pure, 

 the tanning action of "Ironbark " kino is particularly slow. 

 Ten grams of air dried kino containing 2*025 grams of water 

 and 0*064 gram bark and residue, were dissolved in 800 cc. 

 of water, so that 100 cc. contained 0*989 gram solids. The 



