In the same manner I close the screw-thread hole in gas tubes used for conducting steam. I moisten the thread in the sockets with oleic acid from the candle-works, and dust over it a mixture of 1 part of minium, 2 parts of quick-lime, and 1 part of linseed powder (without the oil). When the tube is screwed in the socket, the powder mixes with the oleic acid. The water coming in at first makes the linseed powder viscid. Later the steam forming the oleate of lime and the oleate of lead, on its way to the outer air, presses it in the holes and closes them perfectly.
After a year in use the tubes can be unscrewed with ease, and the screw threads are perfectly smooth.
With this kind of packing only one exception must be made--that is, it is only tight under pressure; condensation or vacuum must be thoroughly avoided.--_Chem. News_.
In answer to various inquiries concerning the manufacture of this article, we give herewith the process of William Henry Balmain, the original discoverer of luminous paint, and also other processes. These particulars are derived from the letters patent granted in this country to the parties named.
Balmain's invention was patented in England in 1877, and in this country in 1882. It is styled as Improvements in Painting, Varnishing, and Whitewashing, of which the following is a specification:
The said invention consists in a luminous paint, the body of which is a phosphorescent compound, or is composed in part of such a compound, and the vehicle of which is such as is used as the vehicle in ordinary paint compounds, viz., one which becomes dry by evaporation or oxidation.
The objector article to which such paint or varnish or wash is applied is itself rendered visible in the darkest place, and more or less capable of imparting light to other objects, so as to render them visible also. The phosphorescent substance found most suitable for the purpose is a compound obtained by simply heating together a mixture of lime and sulphur, or carbonate of lime and sulphur, or some of the various substances containing in themselves both lime and sulphur--such, for example, as alabaster, gypsum, and the like--with carbon or other agent to remove a portion of the oxygen contained in them, or by heating lime or carbonate of lime in a gas or vapor containing sulphur.