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Mica and its uses
2lfica and its Uses.
129
shell, cannot, like ordinary fuzes employed in smooth-bore guns, be ignited by the flame of the exploding charge of powder (as the shell accurately fits the bore of the gun), the fuze composition is inflamed, immediately upon the firing of the gun, in the foliowiag manner : ~ A small quantity of the phosphorus mixtm'e is deposited at the bottom of ~ cylindrical cavity in the centre of the fi~ze, and over it is fixed a small plug of metal, with a pin's point projecting from its lower end. This plug is held in its place by a pin of soft metal, which, by reason of the vis inertice of the plug, is broken when the gun is fired, and the pin tl~en instantly pierces the pellet of detonating mixture, which, by its ignition, sets into action the time-raze. The distance between the pin's point and the phosphorus mixtur% before tile explosion, is only one-tenth of an inch. This arrangement exemplifies in a striking manner the delicacy of action which may be obtained by a judicious combination of simple mechanical arrangements and highly explosive materials. The variety of work accomplished by the explosion of a charge of powder in an Armstrong gun loaded with a shell--no less than five distinct and important operations being thereby effeeted before the shell leaves the gun~afi'ords a most interesting illustration of the progress made in the application of explosives, and of the comparatively great control which may be exercised over the operations of those destrueti~'e agents. l~1iea and its Uses. From the Lend. Mining Journal, No. 1393.
Within the past; few years, we have received several inquiries as to the commercial value of mica, the complaint being that the market appears to be very limited, and that few seem to know the purposes to which it is applied. In last week's Journal, an address was given, by our Canadian correspondent, of a dealer in the material ; and we have since ascertained that Messrs. Nash and Li(~nard of Lime street, are almost the only wholesale dealers in London. ttitherto its use has no doubt been limited, tile manuihcture of ornamental letters for affixing on glass, and of shields for the collection of the smoke fi'om lamp chimneys, being, probably, the applications which have consumed the largest quantity, though it has also been used to some extent for photographic and other purposes. Efforts were made to introduce it for safety-lamps, in the hope that greater light would be obtained with less danger than when the ordinary wire-gauze is employed ; but all attempts in this direction have hitherto failed, and, so far as we can see, are likely to fail, for various reasons. Recently, however, a new field has been in process of opening up, by the endeavor to apply mica, previously colored or metallized, to the decoration of churches, rooms, shops, iYames, and other ornamental and useful purposes. The mica, fi'om its unalterable nature, preserves the gilding, silvering, or coloring from deterioration, and from its diaphaneity, the articles so treated will preserve all their brilliancy.
129
shell, cannot, like ordinary fuzes employed in smooth-bore guns, be ignited by the flame of the exploding charge of powder (as the shell accurately fits the bore of the gun), the fuze composition is inflamed, immediately upon the firing of the gun, in the foliowiag manner : ~ A small quantity of the phosphorus mixtm'e is deposited at the bottom of ~ cylindrical cavity in the centre of the fi~ze, and over it is fixed a small plug of metal, with a pin's point projecting from its lower end. This plug is held in its place by a pin of soft metal, which, by reason of the vis inertice of the plug, is broken when the gun is fired, and the pin tl~en instantly pierces the pellet of detonating mixture, which, by its ignition, sets into action the time-raze. The distance between the pin's point and the phosphorus mixtur% before tile explosion, is only one-tenth of an inch. This arrangement exemplifies in a striking manner the delicacy of action which may be obtained by a judicious combination of simple mechanical arrangements and highly explosive materials. The variety of work accomplished by the explosion of a charge of powder in an Armstrong gun loaded with a shell--no less than five distinct and important operations being thereby effeeted before the shell leaves the gun~afi'ords a most interesting illustration of the progress made in the application of explosives, and of the comparatively great control which may be exercised over the operations of those destrueti~'e agents. l~1iea and its Uses. From the Lend. Mining Journal, No. 1393.
Within the past; few years, we have received several inquiries as to the commercial value of mica, the complaint being that the market appears to be very limited, and that few seem to know the purposes to which it is applied. In last week's Journal, an address was given, by our Canadian correspondent, of a dealer in the material ; and we have since ascertained that Messrs. Nash and Li(~nard of Lime street, are almost the only wholesale dealers in London. ttitherto its use has no doubt been limited, tile manuihcture of ornamental letters for affixing on glass, and of shields for the collection of the smoke fi'om lamp chimneys, being, probably, the applications which have consumed the largest quantity, though it has also been used to some extent for photographic and other purposes. Efforts were made to introduce it for safety-lamps, in the hope that greater light would be obtained with less danger than when the ordinary wire-gauze is employed ; but all attempts in this direction have hitherto failed, and, so far as we can see, are likely to fail, for various reasons. Recently, however, a new field has been in process of opening up, by the endeavor to apply mica, previously colored or metallized, to the decoration of churches, rooms, shops, iYames, and other ornamental and useful purposes. The mica, fi'om its unalterable nature, preserves the gilding, silvering, or coloring from deterioration, and from its diaphaneity, the articles so treated will preserve all their brilliancy.