In light Kundt's name is widely known for his inquiries in anomalous dispersion, not only in liquids and vapours, but even in metals, which he obtained in very thin films by means of a laborious process of electrolytic deposition upon platinized glass.
In 1826 he described the prismatically-coloured films of metal, known as Nobili's' rings, deposited electrolytically from solutions of lead and other salts when the anode is a polished iron plate and the cathode is a fine wire placed vertically above it.
Being produced into delicate tubes which curl round and adher~ firmly to particles of soil, thus at once fixing the root firmly in thi soil, and enabling the hair to absorb readily the thin films of watei ordinarily surrounding the particles (fig.
The water of the soil, which in well-drained soil is met with in the form of delicate films surrounding the particles of solid matter, is absorbed into the plant by the delicate hairs borne by the young roots, the entry being effected by a process of modified osmosis.
The black films of antimony and bismuth and the grey mottled film of mercury are slowly soluble in the acid, and untouched by bleaching-powder.
The black films of tin, lead and cadmium dissolve at once in the acid, the lead film being also soluble in bleaching-powder.
The oxide films of antimony, arsenic, tin and bismuth are white, that of bismuth slightly yellowish; lead yields a very pale yellow film, and cadmium a brown one; mercury yields no oxide film.
The oxide films (the metallic one in the case of mercury) are tested with hydriodic acid, and with ammonium sulphide, and from the changes produced the film can be determined (see F.
Flattened crystals of garnet, films of quartz, and needles of tourmaline are not uncommon.
Sheets of mica are used as a surface for painting, especially in India; for lantern slides; for carrying photographic films; as a protective covering for pictures and historical documents; for mounting soft and collapsible natural history specimens preserved in spirit; for the vanes of anemometers; mirrors of delicate physical instruments; for various optical and many other purposes.
Sericite in the form of scales and films characterizes those portions which have been faulted, squeezed or sheared.
The principle of applying metallic films to glass seems to have been known to the Romans and even to the Egyptians, and is mentioned by Alexander Neckam in the 12th century, but it would appear that it was not until the 16th century that the process of " silvering " mirrors by the use of an amalgam of tin and mercury had been perfected.
In regard to gold this has been proved to be so; gold leaf, or thin films of gold produced chemically on glass plates, transmit light with a green colour.
On the other hand, infinitely thin films of silver which can be produced chemically on glass surfaces are absolutely opaque.
Very thin films of liquid mercury, according to Melsens, transmit light with a violet-blue colour; also thin films of copper are said to be translucent.
It is from such films that the root-hairs absorb all that plants require for their growth.
The movement of water into the root-hairs is brought about by the osmotic action of certain salts in their cell-sap. Crops are, however, unable to absorb all the water present in the soil, for when the films become very thin they are held more firmly or cling with more force to the soil particles and resist the osmotic action of the root-hairs.
Faraday applied it to the preparation of extremely thin films of the metal.
The divisional planes often contain small films of other minerals, the commonest being calcite, gypsum and iron pyrites, but in some cases zeolitic minerals and galena have been observed.
Films of pyrites sometimes coat the joint-planes of coal.
That such enzymes are formed in the protoplasm is evident from the behaviour of hyphae, which have been observed to pierce cell-membranes, the chitinous coats of insects, artificial collodion films and layers of wax, &c. That a fungus can secrete more than one enzyme, according to the materials its hyphae have to attack, has been shown by the extraction of diastase, inulase, trehalase, invertase, maltase, raffinase, malizitase, emulsin, trypsin and lipase from Aspergillus by Bourquelot, and similar events occur in other fungi.
By saponification it yields a number of fatty acids - palmitic, myristic, oleic, linolic, linolenic and isolinolenic. Exposed to the air in thin films, linseed oil absorbs oxygen and forms " linoxyn," a resinous semi-elastic, caoutchouclike mass, of uncertain composition.
Kundt prepared metallic films of iron, nickel and cobalt, and obtained powerful negative optical rotation with them (Wied.
He also greatly facilitated the study of liquid films by showing how to form a liquid, the films of which will last for twelve or even for twenty-four hours.
P. 620) experimented on liquid films, and showed how a film of a liquid of high surfacetension is replaced by a film of lower surface-tension.
Those films are being made now.