THE TECHNOLOGIST. [Dec. 1, 1864. 



230 THE CIRCULATION OF SAP IN TREES, 



or liquid state, a portion only is taken tip, while the gum from the 

 stringy bark is completely dissolved. When, as in the case just cited, a 

 flocculent residue remains after the action of water, a few drops of am- 

 monia render the solution perfect. 



The aqueous solutions of the eucalyptine gum-resins all give an acid 

 reaction with test-paper ; but the differences in the behaviour of each, 

 when dissolved by water, subjected to the several re-agents, become 

 very manifest. The precipitate caused by a solution of gelatine — indi- 

 cative of tannic acid — does not appear in any case to correspond in 

 quantity with their intense astringent taste ; and occasionally the addi- 

 tion of that substance causes no precipitate at all. This fact has an 

 important bearing upon the value of this whole class of bodies under 

 consideration for tanning purposes, and as substitutes for catechu and 

 similar bodies. 



With acetate of lead these astringent bodies give copious gelatinous 

 precipitates ; and with the salts of iron various shades of green and 

 black. The mineral acids also determine in them bulky flocculent 

 deposits. 



One or more of the substances which have been made the subject of 

 the foregoing very imperfect sketch appear to have been forwarded from 

 these colonies from time to time, in small quantities, to Great Britain, 

 and to bear there the name of Botany Bay kino ; but little seems to be 

 known respecting their properties or uses, the general belief being that 

 Australian kino is only furnished by the Ironbark tree (E. resinifera). 

 It becomes, therefore, the more necessary to follow up this subject to a 

 conclusive termination, to establish by a searching chemical investiga- 

 tion the proper uses of substances so abundantly available, and thereby 

 increase the industry and prosperity of the land. 



THE CIRCULATION OF SAP IN TREES, AND THE FORMATION 

 OF MAPLE SUGAR. 



Trees are made up of fine tubes which extend from the root to the leaf, 

 and it is through these tubes that the circulation of the sap is carried 

 on. If a growing tree is pulled up by the roots, and the roots are placed 

 in a vessel of water containing some coloured solution which they will 

 absorb, we can trace the course of this coloured solution through the 

 tree by cutting notches into it at successive periods. The colouring 

 matter is always found first in the body of the wood near the root, then 

 in the wood higher up, and so on until it reaches the leaf ; then it 

 begins to appear in the inner bark near the leaf, and it passes down 

 through the bark again to the root. This observation shows that the 



