BY THOS. STEEL. 



257 



Another sample of Gidgee ash offered commercially for manurial purposes 

 and examined by myself in 1898, contained a similar large proportion of lime 

 and small one of potash. 



Being struck by the probability of this proportion of lime being due to 

 the presence of unusual amounts of calcium oxalate in the plant, I obtained 

 from Mr. Maiden samples of the timber and bark of A. Cambaijei and sub- 

 mitted them to detailed examination, with the results following: — 



I have calculated the oxalate as C204Ca-|-H20, following H. G. Smith, 

 cited above, v.ho found this to be the constitution of the oxalate separated 

 mechanically from Eucalyptus bark. The method of determination used was 

 similar to that described by Smith, with the exception that T ignited the oxalate 

 precipitate completely and weighed as CaO. 



Timber and bark of Acacia Cambagei. 



(Calculated to dryness.) 



Outer 



bark.' 



Ash soluble in acid 8.48 



Sand 1.15 



Potash (K2O) 0.06 



Lime as oxalate 8.20 



Total lime (CaO) 7.22 



Calcium oxalate (C204Ca-|-H20) 18.82 



Water in air-dried sample 



8.80 



9.30 



9.00 



9.20 



9.05 



These proportions of calcium oxalate in the bark of A. Cambagei are the 

 highest I have seen recorded for any plant. 



G. Kraus (Journ. Chem. Soc, 1892, abs. ji. 1370) concludes from the re- 

 sults of experiments on the bark of various trees which contain calcium oxalate 

 in quantity, that this substance constitutes a reserve deposit and is not an 

 excretion, and that it is redissolved in spring and summer according to the 

 needs of the plant. Branches of Rihes sanguineum and other trees varied in 

 their calcium oxalate content with the seasons, the amount present being highest 

 in winter and lowest in spring and summer. The author states that calcium 

 oxalate is certainly liable to solution by long-continued action of an acid circu- 

 lating liquid like cell sap. 



The abstract does not give any details regarding the structure or appear- 

 ance of the bark examined. I feel more than doubtful about this conclusion. 

 A fall in the oxalate content of the bark during the growing period is more likely 

 to be due to the addition of new bark free from oxalate, than to the solution of 

 the oxalate already deposited. Oxalic acid is usually considered a waste pro- 

 duct, harmful to the plant, fixed with lime in order to render it insoluble and 

 harmless, and we know that it is shed in large amount in leaves and bark. 



We have seen above that the dead, dry, outer bark of A. Cambagei contains 

 the same proportion of oxalate as the inner bark, and even of the latter only a 

 comparatively thin layer may be in metabolic function, in which condition alone 

 it could receive or part with its load of oxalate. 



Smith (Journ. Roy. Soc. N.S. Wales, xxix., 1895, p. 325; xxxvii., 1903, 

 p. 107) concluded in the case of rites e.rceha, which he found to contain large 

 amounts of aluminium succinate, that the succinic acid wa.s a waste, poisonous 



