156 Progress of Invention, 



PROGRESS OF INVENTION. 



Economic Fuze for Mining, and other Purposes. — A very simple 

 and inexpensive fuze has recently been invented. It is made by 

 doubling about five inches of thin copper bell wire, which has been 

 coated with gutta percha, twisting about one inch of the looped end, 

 and separating the extremities of the untwisted portions, so that the 

 whole will be in the form of a two pronged fork, of which the twisted 

 part forms the handle. The top of the twisted part being then cut off, 

 the severed portions of the cut end are so near each other, that, 

 when the free ends are connected with an induction coil of very 

 small power, sparks will pass between them. The cut end is then 

 placed in the open extremity of a small oblong capsule formed of 

 very thin sheet lead, and containing a mixture which has been made 

 by triturating ten parts by weight gunpowder such as used for 

 fowling, and one part charcoal made of spindle-tree wood, the mixture 

 having been previously moistened with ordinary collodion. When 

 the cut end of the twisted wire has been inserted in the capsule, the 

 lower edge of the latter is to be fastened to the former, by means of 

 thick gum lac varnish. The smallest spark passing between the 

 cut ends of the twisted wire will ignite the composition in the cap- 

 sule, and this will ignite any explosive substance in which it may 

 have been placed. 



New Galvanic Battery. — The notice of the Academy of Sciences- 

 has recently been drawn to a battery of a new kind, which is said to 

 have acted extremely well, for electrotype purposes, during several 

 months. It is founded on the fact that aqua regia will not dissolve 

 perfectly pure silver ; it merely covers the silver with a thin coat- 

 ing of chloride, that protects it completely from further action, so 

 that it may be immersed for an indefinite period in the aqua regia r 

 without undergoing further change. If the silver contains copper, 

 or the aqua regia has been made with an excess of nitric acid, or 

 even with equal quantities of nitric and hydrochloric acids, the 

 silver will, to a greater or less extent be changed into a chloride. 

 Two-thirds hydrochloric and one-third nitric acid, or three-fifths of 

 the former and two-fifths of the latter were found to answer well. 

 The battery was a Grove-Bunsen formed of silver, aqua regia, zinc, 

 and sulphuric acid diluted as usual. After having been in action 

 for some months, the silver was not found to have lost any percep- 

 tible weight, nor was there any chloride in the porous vessel con- 

 taining the silver and aqua regia. 



A Very Simple Electrical Machine. — This machine is an im- 

 provement on that of M. Holtz. It consists of a disc of strong 

 paper, 30 centimetres in diameter, mounted on an axis made of glass 

 tube or some other non-conducting material, and capable of being 

 made to revolve about fifteen times in a second, by means of wheels, 

 an endless band, and a handle. In front of the disc are two me- 

 tallic rods having pointed extremities which are perpendicular to- 

 the disc, being turned towards it, and at equal distances from its 

 centre. The remaining portions of the rods are bent perpen* 



