2) is employed, in which the absorbent is protected by a second pipette containing water.
In special cases, such as the preparation of edible oils and fats, a further improvement in colour and greater purity is obtained by filtering the oils over charcoal, or over natural absorbent earths, such as fuller's earth.
Large quantities of ground mica are used in the manufacture of wall-paper, and to produce a frosted effect on toys, stage scenery, &c. Powdered mica is also used in the manufacture of paints and paper, as a lubricant, and as an absorbent of nitro-glycerine and disinfectants.
The soil of yards and the floors and walls of houses rapidly become contaminated, and the ideal condition would be to have an impermeable flooring covering the whole area, and supplied with suitable layers of sand, sawdust, peat-moss or other absorbent substances which can be changed at frequent intervals.
On the other hand, water should be given generously in hot weather, also when absorbent stone is used or when the concrete is not rammed.
In both Psilotum and Tmesipteris the functions of the root-system, which is completely absent, are performed by leafless rhizomes bearing absorbent hairs and inhabited by an endophytic fungus.
The two most important tobaccogrowing districts are: the Black Patch, in the extreme south-west corner of the state, which with the adjacent counties in Tennessee grows a black heavy leaf bought almost entirely by the agents of foreign governments (especially Austria, Spain and Italy) and called " regie " tobacco; and the Blue Grass Region, as far east as Maysville, and the hill country south and east, whose product, the red and white Burley, is a fine-fibred light leaf, peculiarly absorbent of licorice and other adulterants used in the manufacture of sweet chewing tobacco, and hence a peculiarly valuable crop, which formerly averaged 22 cents a pound for all grades.'
The damping of all absorbent surfaces, such as the floors or bare walls, &c., is frequently necessary several times a day in the growing season, so as to keep up a humid atmosphere; hence the advantage of laying the floors a little rounded, as then the water draws off to the sides against the kerbstone, while the centre remains dry for promenaders.
During this season the rivers, which are roaring torrents throughout the monsoon, are almost all lost in the dry, absorbent plains.
They may be separated in a similar way by concentrated sulphuric acid, which has the same absorbent effect on the one class, and not on the other.
The early segmentation of the embryo differs in the several groups, but usually the first leaf or leaves, the apex of the stem and the first root are differentiated early, while a special absorbent organ (the foot) maintains for some time the physiological connexion between the sporophyte and the prothallus.
They contain much clay and marls, non-absorbent and subject to such excessive wash that vegetation cannot gain a foothold.
The same absorbent' quantitatively takes up any halogen and sulphur which may be present.
At that point, however, quartz and even atmospheric air become strongly absorbent and the expensive fluorspar becomes the only medium that can be used.
The method consists in comparing the intensity after transmission through a layer of known thickness of the absorbent with the intensity of light from the same source which has not passed through the medium, k being thus obtained for various thicknesses and found to be constant.
The subsoil too is differently formed: the surface consists of very absorbent materials, then comes a stratum of less permeable tufa or peperino (sometimes clay is present), and below that again more permeable materials.
Kieselguhr, for it is too valuable as an absorbent of nitroglycerine, for the manufacture of dynamite, to be available for making pozzuolanic cement.