1856.] of Chemistry to Military Purposes. 285 



The bullets used in the shrapnel shell, of which Captain Boxer's 

 improved form was exhibited, were made of an alloy of lead and 

 antimony. At the present prices of 'the metals, the value of the 

 alloy would be about £34 per ton ; an alloy of these metals, 

 obtained direct from an antimonial lead ore, and sufficiently rich 

 in antimony, was imported in considerable quantities from Hungary, 

 and purchased at a price of about £19 per ton. An antimonial 

 alloy was also used for coating a coarse canvas, forming with it a 

 durable covering for roofs of light buildings, and for the manufac- 

 ture of screw-plugs, which, being fitted into the fuse-openings of 

 shells charged with powder, rendered the transport of the latter in 

 that state a matter of perfect safety. 



The ease and certainty with which charges of powder, in cannon, 

 were ignited by the explosion of a mixture of the native sulphide of 

 antimony with chlorate of potassa and a little glass, either by fric- 

 tion or a blow, was pointed out, and the mode of applying this 

 mixture experimentally demonstrated. In connection with the 

 various ingenious contrivances used for firing guns and mortars by 

 this means, an outline was given of the method lately introduced by 

 Colonel Eardley- Wilmot, of firing guns heavily charged, for proof, 

 by galvanic agency, whereby this hitherto hazardous operation was 

 placed completely under the control of the person conducting the 

 proof. 



Tin was employed for the manufacture of protective capsules 

 for the time-fuses invented by Captain Boxer, and, in admixture 

 with a small quantity of copper, or as a coating upon that metal, 

 for the manufacture of large powder-canisters. The most important 

 application of tin was to the formation of the alloy with copper, 

 known as gun-metal. In speaking of this alloy, Mr. Abel pointed 

 out some important difficulties with which the bronze gun-founders 

 had to contend, and which were mainly due, on the one hand, to 

 the volatilization of some of the tin, at the temperature to which 

 the metal had to be raised ; and on the other, to a tendency to the 

 separation, in the mass of metal, during the cooling of a casting, of 

 small quantities of a very hard white alloy, which, in assuming a 

 crystalline form, frequently gave rise to small cavities in the casting. 

 The first difficulty was to some extent overcome by the addition of 

 the tin to the melted copper and old gun-metal, in the form of an 

 alloy of one of tin to two of copper (known as hard metal) , at as 

 brief an interval before the metal was cast as was consistent with 

 the formation of a homogeneous alloy ; the second difficulty alluded 

 to was the more formidable one, and had hitherto baffled the efforts 

 of metallurgists to overcome it. A searching investigation into the 

 causes, and the possible means of preventing this partial separation 

 of the metals, was at the present time being carried on. 



Allusion was made to other alloys of copper, such as Stirling's 

 and Muntz*s metal, and to the employment of sheet copper in the 

 manufacture of percussion caps. Mr. Abel demonstrated experi- 



