GUMS, RESINS, AND OTHER VEGETABLE EXUDATIONS. 183 



The gum was dissolved in water, and the flocculent, pale-red 

 precipitate obtained by adding sulphuric acid, was washed until 

 the acid reaction of the wash-water ceased; the precipitate was 

 dissolved in boiling water, and separated after cooling from the 

 insoluble matter. The red liquid was evaporated in vacuo and 

 yielded thin, red, transparent laminse, which under the microscope 

 appeared cracked, and quite amorphous. The mass is slowly 

 soluble in cold but readily in hot water; the solution is astringent. 

 Alcohol, like hot water gave a ruby coloured solution; perchloride 

 of iron produces a dirty green precipitate. The kino-tannic acid 

 obtained from kino itself gave with the iron-salt a black-violet 

 precipitate; but as the author is far from looking upon this acid 

 as a definite chemical compound, he thinks he has proved the 

 identity of the principal constituent of the gum under examination 

 with kino. He adopts the name Eucalyptus kino, and avoids 

 the expression gum, because 1 gums are mostly soluble in alcohol 

 as well as in water. In Bentham and Mueller's " Flora Australi- 

 ensis," the many extracts obtained from Eucalyptus are always 

 called gums, and in Yol. iii. 185, it is even stated that the 

 Eucalyptus species yielded gum-resins, and therefore they were 

 named gum-trees. 2 



"Pterocarpus kino contained, besides kino-tannic acid, water, 

 mineral substances, with 13 per cent, of ash, a substance similar 

 to pectine, catechine and a little pyro-catechine, but no sugar. 

 Eucalyptus kino contained from 15 to 17 per cent, of water; it 

 gave only a trace of ash, and no sugar was found. Several samples 

 contained a little catechine. Pyrocatechine appears always to be 

 present. A pectine-like substance could not be detected in any 

 of the samples, but several samples contained a substance soluble 

 in water, similar to gum arabic. The juices of E. gigantea, Hooker, 

 (E. obliqua, L'Herit.) contained this substance in such quantity 

 that several lumps were quite insoluble in alcohol. 



1 The word " these " is obviously omitted here. 



2 They are called gum-trees by reason of these exudations, and it is 

 very excusable for Bentham, who was not a chemist, to call them " gum- 

 resins." Neither are they " extracts." 



