The astringent principle is a peculiar kind of tannic acid, called by chemists quercitannic, which, yielding more stable compounds with gelatine than other forms, gives oak bark its high value to the tanner.
The growth of an organic being is simply a process of enlargement, as a particle of dry gelatine may be swelled up by the intussusception of water; its death is a shrinkage, such as the swelled jelly might undergo on desiccation.
Holland is a grain and fruit shipping centre, and among its manufactures are furniture, leather, grist mill products, iron, beer, pickles, shoes, beet sugar, gelatine, biscuit (Holland rusk), electric and steam launches, and pianos.
But the wet collodion process was then the only one available, and its inconveniences were such as to preclude its extensive employment; the real triumphs of photographic astronomy began in 1875 with Huggins's adoption and adaptation of the gelatine dry plate.
The culture of such algae may prove of economic importance; gelatine, glue and agar-agar would be valuable by-products.