(57) L. D. writes that benzine will answer much better to exterminate roaches, moths, etc., than anything else. It will not hurt furniture in the least, will evaporate, and can be easily applied.
Minerals, Etc.—Specimens have been received from the following correspondents, and examined, with the results stated:
M. B. W.—No. 1 is a silicious clay—it might be useful in the manufacture of some grades of pottery, etc. No. 2 is a ferruginous shale—contains about 80 per cent. of silica and 10 per cent. of alumina, besides lime, magnesia, iron oxide, and water.—W. S.—It is fibrous talc—talc of good quality is in considerable demand for paper making and other purposes.—W. G. H.—The sand contains no precious metal—the glittering particles are mica.—S. F.—The specimen you send consists of a mass of the long hairs which have been attached to the seeds of the "milkweed" (asclepias), or, as it is sometimes called, from the silky nature of these appendages, "silkweed." We believe that this material is put to no other economic use at present than that of a filling for cushions and pillows. The beauty of this silk like down long ago attracted attention, and many unsuccessful attempts have been made to put it to some practical use in the arts; but, as you have probably noticed, the hairs are both brittle and weak, and an examination with a lens will show that it wants the roughness and angularity necessary to fit it for being spun like other fibers. It has, however, been mixed with cotton and woven into fabrics having a silky luster and capable of taking brilliant dyes, but the manufacture has never been prosecuted. The plants, though widely distributed over the United States, and quite common, are nevertheless not abundant enough in a wild state to afford much of a supply, and we believe no experiments have been made in cultivating them.
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COMMUNICATIONS RECEIVED.
The Editor of the Scientific American acknowledges with much pleasure the receipt of original papers and contributions on the following subjects:
Manufacture of Porous Cups for Tyndall Grove Battery. By W. H. S.
Cylinder Condensation. By F. F. H.
Sawdust. By W. H. M.
Keely Motor. By G. R. S.
Firing. By A. P. A.
Steam Launches. By G. F. S.