1888.] Aluminium in certain Vascular Cryptogams. 125 



Mr. Howlett's specimen of ash was handed to me by Mr. Thiselton 

 Dyer; the following resnlts were obtained on analysing it, every 

 precaution being taken to ensure an accurate result : — 



100 parts of ash contained 



< • , 



A1 2 3 . Si0 2 . K 2 0. 



•Tree-fern, New Zealand 19 65 12 96 151 



This entirely unexpected discovery of nearly 20 per cent, of alumina 

 (two determinations gave 19*8 and 19*5) in the ash of a tree-fern 

 induced me to examine the ashes of known species of other Cyatheacea3 

 for this substance. Three specimens of the caudex of distinct species of 

 these plants were furnished by the kindness of the Director of the 

 Royal Gardens, Kew. Of these one only was sufficiently free from 

 adventitious impurities to admit of trustworthy analysis. A cross 

 section of the caudex of this plant, Cyathea serra from the West Indies, 

 was sawn so as to preserve intact the whole of its pith as well as its 

 fibro- vascular sheath. This section was broken up and burnt to a 

 white ash, which amounted to 2 - 7 per cent, of the material dried at 

 100°. But it gave, on careful analysis, the merest trace of alumina. 



100 parts of ash 

 contained 



Percentage of ash ( A 



in dry plant. A1 2 3 . SiO*. 



*Cyathea serra 270 0'20 12-65 



Even this trace of alumina may have been extraneous, since the silica 

 obtained was not entirely free from sandy particles (about 1 J per cent, 

 of the ash), although the material taken for the preparation of the ash 

 was apparently perfectly clean. 



Mr. Howlett forwarded, with the ash of the unknown tree-fern, a 

 few grams of the caudex of a plant of Cyathea medullaris. The 

 amount was quite insufficient for a satisfactory determination of the 

 ash and its constituents, so I was obliged to content myself with a 

 qualitative examination for alumina. The very small quantity of ash 

 which I obtained on the incineration of these fragments of C. medullaris 

 gave abundance of alumina. Indeed, I should not be surprised to find 

 that the ash of the undetermined tree-fern was really that of this 

 species of Cyathea. If this be the fact alumina will have been 

 recognised, at present, in but a single species of tree-fern. Other 

 genera of Cyatheaceae, such as Alsophila and DicJcsonia, may of course 

 be characterised by the presence of this earth in notable quantities, 

 but as yet analyses are wanting. 



So far, it will be seen, alumina has been found in important quanti- 

 ties in a single tree-fern and in a number of different kinds of Lyco- 

 podium. The ash of another plant, however, contains over 2 percent. 



