Technical and Chemical Notes.

Progress, Volume VII, Issue 2, 1 December 1911, Page 897

Technical and Chemical Notes.

FROM OUR SPECIAL CORRESPONDENT. New Inventions in Dyes and Paints. A chemical firm in Germany recently succeeded in manufacturing a dye of an intensive yellow. It is obtained by heating up indigo with aromatic acid-halo-genides with the aid of. condensation agents, such as metals or metallic salts. There is a great future for the new yellow dye, as may be gathered from the following facts. The War Departments of all countries of the world are trying to find a suitable colour for new army uniforms. It is essential that these colours be fast. Dyes produced in the copper are much more durable than those made in the old way. It has, however, been impossible to obtain all shades of colours produced in the copper, since a pure yellow has been wanting. The new indigo yellow may be used with all other copper colours, hence being of untold importance in the dyeing of woollen goods. With its aid every shade of khaki, field-gray and fieldgreen may be obtained. Any imaginable nuance may also be imparted to silk; at the same time the colours are faster than any yet produced. The new dye is also destined to play a leading part in silk weaving, since the copper dye may be subjected to precisely the same boiling as the silk.

Caseine colours are used in painting pictures, and also for wall paintings (“sgraffito painting”). Gaseine paintings are not affected by time, and their colours possess considerable charm, fire and depth. They often have been done in the form of mural paintings in public buildings, churches, town halls, etc. Caseine preparations may be used to advantage as impregnating agents for rendering painting surfaces firm. There are other specialties in paints in the form of mineral colours, which are guaranteed to be acidproof, free from lead, and heat proof. Also, being rust and weather-proof, they may be used for painting bridges, gas tanks, corrugated iron structures, etc. One of the new paints, called “Preolit,” stone protector, is a solution to keep stone from decomposing and to render cement floors dustless. “Kautscholeum” is the name of a permanent paint for indoor or outdoor use. It replaces oil paints and may be adopted for painting buildings, to protect them from pouring rains.

“Vitralin” is a brilliant colour for interior and exterior, painting. Being germicidal, it is particularly of use in painting stables, butcher shops, hospitals, etc. To produce a durable brilliant green patina very quickly on copper roofs, steeples, etc., one should employ “Mathalit,” which costs 10/- a liter, this being sufficient to cover 100 sq. yards. Finishes are employed in the textile industry to give thread or finished fabric an appearance conforming to the demands of fashion. By using certain finishes, it is possible to : impart to cotton material the character of linen; satin texture furnished with satin dressing is a good imitation of silk. Finishes also play an important part in the manufacture of woollen, half-woollen and worsted goods. Their composition depends on the nature of the material. Starch paste, dextrin, glue, soap, wax, kaolin, stearin, soda, gelatine, etc., are used in preparing the finishes, glycerine as a rule being added. Glycerine is a leading article of trade, and is subject to much speculation. The price of the refined product varies according to the quality, between £5 and £7 per 100 kilograms (2cwt.). Efforts, therefore, have been made to find a substitute for glycerine, for use in making the finish. And it may safely be said that there are excellent substitutes to be had at the present time. I will mention the products sold under the names of “Glyceroeollo” and “Glycerine Substitute,” which are much in demand.

There have been several kinds of dry plaster in the market for some time. They are to be had in all colours, and are used principally for making plaster for the fronts of buildings. Dry plaster is a mixture of pulverised slaked lime and a diluting agent, which, is reduced to a plastic mass with water. It may be used as plaster if applied immediately, as it rapidly hardens. The lime must be slaked and ground up very carefully for producing a good plaster. Dry plaster may be stored for a long time without losing any of its binding power or depreciating in quality. When applied to walls, it is weather-proof, and may be cleaned by washing with water, soapwater, or diluted acids. The plaster may be obtained in various grains, different ones of which are to be preferred for smooth or fluted plaster. The press plaster process is an innovation in this field, the plaster being provided with relief designs, with stamps. If large surfaces are to be plastered, it is a new method to do the work pneumatically. The plant is portable, its principal parts being a pump forcing the plaster through a flexible tube at the end of which there is a nozzle. The plaster is blown out of the nozzle on to the wall like a rain of mud.

A Substitute for Platinum. Last year the price of platinum increased above £SO a kilogramme, so that it now amounts to almost £3OO. This is due to no new deposits of it having been discovered. It is found in the Ural Mountains and the Caucasus, in California, Australia and Sumatra. A second reason for its high price is that it is being turned to many uses. The chemical, incandescent lamp, motor car, and jewellery

industry, and dentistry, make use of large quantities. Vessels of platinum are employed for chemical purposes, owing to their withstanding high temperatures and to their being highly insensible to chemicals. Bowls and crucibles for the same purpose have recently been made of 10 parts platinum and 90 parts gold, thereby considerably reducing their cost. These vessels can stand a temperature of 1000 degrees Celsius, and are almost as durable as pure platinum vessels. There is a slight shimmer of gold about them, otherwise they look exactly like platinum. A firm in Hanan, Bavaria, has begun the manufacture of these vessels.

Electric Heating and Cooking. The application of electric cooking and heating apparatus for household purposes still meets with considerable opposition, in spite of the fact that it has been demonstrated that electricity is highly economical and the apparatus thoroughly stable and able to withstand hard tests for many years. If the kilowatt hour of electricity is reckoned at it is cheaper to work with it than with gas at the . rate of l%d. per cubic meter. There are also other advantages to be considered: its readiness for immediate use, the absence of fuel and waste gases, the security against fire, and exact regulation of the cooking, with low consumption of power. Undoubtedly considerable progress will be made in the near future in the introduction of electric heating and cooking apparatus, since several leading firms of the electrotechnical branch have been reported as about to begin the manufacture of solid apparatus at a low price. Electric heating and cooking has been used for several years in industry and the crafts, and are continually becoming more popular. The latest form of application is the electrically heated baking oven, suitable for use in the country and on vessels. It may be employed for any kind of pastry, and is far superior to ovens heated with wood, as regards cleanliness and practicability. , The firm constructing the ovens have a model bakery at work, which may be inspected if desired. Electrically heated water distilling apparatus for producing pure water, are of importance to pharmacies, laboratories and electricity works (storage batteries). Electric heating carpets for warming floors are a further innovation.

* * * Use of Electro-Magnets. The electro-magnet is being used more and more in machine construction. Lifting magnets are employed for loading rails and pig iron, electro-magnets for fixing machine parts on the face plate of a lathe. Electro-magnetism has been adopted for another purpose, in the form of a magnet gripper with a handle on the side two feet long. This is a kind of common hand magnet and is used for lifting up small objects hard to grip with a pair of tongs. The apparatus is water and fire-proof, so that it may be used for taking hot pieces of iron or steel from the annealing or tempering furnace and dipping them into an oil or water bath. It may also be employed for putting iron and steel pieces into and taking them from, galvanic baths. These magnetic grippers are constructed for direct currents of 3 to 220 volts, and may be con-

Reeled directly to any light or power conduit. Their weight is about 4%1b5., and their bearing force up to 221 b. As a rule, a conduit of 9 feet long with a connection plug are supplied with them, the button switch is on the gripper. For high voltages a resistance must be used.