258 OCCUKRENCE OP CALCIUM OXALATE IN THE GIDGEE WATTLE. 



metabolic product, fixed by the jilant witli the only available base forming an 

 insoluble succinate, in order to get rid of it. 



To determine in how far the barks of other species of Acacia resembled 

 ,1. Cambaijei in calcium oxalate content, the barks of a number were examined. 

 Through the courtesy of Mr. Maiden 1 was provided with these from the col- 

 lections in the Herbarium Museum at the Botanic Gardens, Sydney. The 

 analysis of this series was made for me by my colleague, Mr. E. F. Vaughan, 

 to whom my thanks are due. All the samples were of mature bark which had 

 l>eeome thoroughly air dried. 



Percentages in Acacia barks (calculated to dryness). 



12 3 4 5 6 



Total ash 2.01 1.56 3.05 6.80 6.14 6.05 



Total lime (CaO) 1.64 0.91 2.63 2.54 4.04 5.60 



Lime as oxalate 0.52 0.60 1.67 2.05 2.58 3.42 



Calcium oxalate (C204Ca+H20) 1.3(i 1.56 4.36 5.35 6.74 8.92 



Water in air-dried sample . . . . 11.43 11.75 13.20 9.58 12.88 10.83 



In the total ash the lime was ignited to CaO. 



1. A. Cheelii Blakely; 2. A. adunca A. Cunn.; 3. ^1. aurlculiformis A. Cunn. ; 

 4. A. decora Reiehb. ; 5. A. salicina Lindl. ; 6. A. aueura F.v.M. 



As in the case of the Eucalyptus barks examined by H. G. Smith there is 

 considerable variation in the amount of oxalate present, but in none of the 

 samples is the high percentage in .1. Camhagei approached. A variable amount 

 of lime is seen to be in combination other than as oxalate. The bark of A. 

 decora contained a comparatively large amount of ash insoluble in acid an(i was 

 high in iron and alumina, which might be due to admixture with earthy matter, 

 but there was nothing Ln the appearance of the bark to indicate this. 



In a lengthy article on the chemistry of forest trees, by R. Warington in 

 Watt's Diet. Chemistry (viii.. Ft. 1, 1879, p. 800), a considerable mass of in- 

 formation on the ash 'constituents of the bark, timber and leaves of trees is col- 

 lected. A critical examination of this shows clearly that in most of these lime 

 is the predominating constituent, and that there is never sufficient inorganic 

 acid present to fully satisfy the lime and other bases. Throughout the article 

 no specific mention is made of oxalic acid, though it is stated (p. 809) that the 

 carbon dioxide in the ash represents tlie organic acids with wliich the bases 

 were originally united, and that the proportion of btises combined in this way 

 is apparently gTeater in old than in young wood [and bark.] In the light of 

 present knowledge a study of the data given strongly indicates the presence, in 

 many of these timbers and barks, of vcrj' considerable proportions of calcium 

 oxalate. 



