Agricultural Chemistry. 125 
only the upper, in others, both sides contain silica in the epidermal cells. 
In some the hairs alone, in others the hairs and epidermal cells also, are 
incrusted with this body. In Deutzia and Ficus elastica the vascular 
tissue is incrusted with silica. Wicke found that the bark of the beech 
and maple, Acer pseudoplantanus, are coated with silica. This is especially 
true of the beech which is literally enveloped in a silicious shirt of mail, 
Whence the smooth and undecayed surface which its trunk presents. From 
the inner bark—bast-fibre—of flax, Wicke obtained after destruction of 
the organic matter, well characterized elongated cell-skeletons of silica. 
In the ashes of old linen he found 28 per cent of this substance. In the 
fibers of Manilla hemp, Musa textilis, Aloe hemp, Agave Americana, New 
Zealand flax, Phormium tenaz, all tenacious textile materials, Wicke found 
as in flax, the entire cells incrusted with silica, In cotton fibre it is want- 
ing. In jute, Corchorus teztilis, some cells are partially incrusted. Wicke 
concludes that the durability of textile fibres is to a degree dependent on 
their content of silica. 
this ace According to Arendt (Das Wachsthum der Haferpflanze, 
P. 180) the different parts of the oat contain the following quantities of 
silica respectively : 
Amount of sili Insoluble 
Parts of dey oer a epee eee oui: Total. 
Lower part of the ste . 0°33 1-41 174 
Middle part of the stem, 0°30 4°82 5-12 
re se of the stem, 0°36 13-02 13-38 
Lower leaves, 0°86 34°37 35°28 
Upper leaves, 052 43°35 43°87 
We see then plai f the stem and leaves contain 
om plainly that the upper part of the s 
More wn than the ‘fre parts, while the lower parts certainly need to 
s the greatest degree of strength. 4 
In the second vinnie the great variableness observed in the same plant, 
In the same part of the plant, as to the content of silica, would seem 
‘0 indieate that this substance is to some degree accidental. : 
.. 1 the ashes of ten kinds of tobacco leaves, Fresenius and Will found 
Tange from 5°14 to 18°39 per cent. 
The analysis of the ash of 13 samples of pea-straw, grown on different 
Soils from the same seed during the same year, under direction of the 
oo Economie Collegium” of Prussia, gave the following percentages 
silica, viz: 0°56; 0-75; 2°30; 2°32; 2°80; 3°29; 3°67: 5:15; 5°82; 
17 3°02 ; 
2—Journal fir prakt, Chem, xlviii, 474-7. 
