PROCEEDINGS OF SECTION B. 87 



This tint was easily matched by the aid of the green, solution obtained 

 by boiling a few drops of alcohol in potassium dichromate, together 

 with a solution of potassium chromate. Three-quarters of a litre of 

 this solution contained in a large beaker was stood before a window, 

 and the value of 20 c.c. of the indigo tin in | litre water exactly deter- 

 mined. 10 c.c. of the kino solution, with 20 c.c. indigotin in the same 

 quantity of water in a beaker the same size were then titrated, and the 

 tint again adjusted so as to exactly match that of the standard 

 solution. This was easily done, and at the end a single drop of 

 permanganate was sufficient to bring about a perceptible change of 

 colour. The value of 10 c.c. of tannic acid was also determined from 

 which the ratio was calculated. This method of titration was found 

 to be far more dehcate than when a porcelain dish was used. The 

 titrations were always carried out in a uniform manner. 



The rapidity by which gelatinization takes place with some of the 

 kinos when a few drops of formalin are added to a tincture of the kino, 

 B.P. strength, also has a discriminative value. Jellies are formed 

 more readily when the kinos are dissolved in 50 per cent, alcohol than 

 when 90 per cent, alcohol is used, gelatinization is even more rapid 

 with some kinos in aqueous solution with the formalin test. 



A large proportion of eucalyptus Idnos belong to intermediate 

 species, and their reactions are thus somewhat indefinite in character, 

 due to the tannins and other constituents overlapping. The kinos 

 in which interfering constituents are present in a minimum amount 

 have, however, distinctive reactions, so that it has been possible to 

 arrange them, here in the following classes : — 



Class I. 



Kinos of this class are exuded by species allied to and including 

 the " Peppermints " and the " Stringy barks," and those of E. dives, 

 E. piluhris, E. macrorrhyncha, E. delegatensis, &c., are good represen- 

 tatives of this class. When freshly exuded these kinos are soluble in 

 water and mostly so in alcohol, although many of them contain some 

 Emphloin, and thus show association with the mejnbers of Class IV. 

 They have an astrmgency value above 700 (gallo-tannic acid = 1,000), 

 some even exceeding 800, and do not contain either Eudesmin or Aro- 

 madendrin, as evolutionary processes have eliminated these bodies 

 from the kinos at this end of the series. They become less soluble 

 with age, and the glucoside appears to be absent from representative 

 kinos of this class. They gelatinize readily in tinctures, even more 

 easily in aqueous solutions with the formalin test, and give charac- 

 teristic reactions with reagents. The tannin, however, is not readily 

 absorbed by hide substance, although precipitated by gelatine. They 

 give in aqueous solutions {-} gram kino per litre) with ferric chloride 

 a violet colouration soon forming a precipitate, and after some time a 



