238 Mr. Mallet on the Physical Conditions 



May it not be that the well-known superiority and endurance of old Spanish 

 cast guns is due not merely to their exclusive use of new metals for every cast- 

 ing, but to the existence of a minute proportion in the alloy of the alkaline 

 metal, potassium, arising from the Spanish copper being smelted with wood 

 fuel, and the foundry meltings performed with the same ? Bell-founders are 

 of opinion that wood fuel improves their metals, though its use is abandoned 

 in England, from motives of economy, in favour of coal, with which all our 

 copper is smelted. The well-known and most remarkable ductility, softness, 

 and fluidity iu fusion of Spanish pig-lead is probably due to the same cause. 



181. The experience of ages has made the casting of bronze guns a matter 

 almost of routine ; but the results, as might be expected from the many conditions 

 of difficulty thus briefly treated of, are still often uncertain or unmanageable. 

 Some old Spanish guns, of large caliber (and the latter are less durable, than 

 smaller guns) are stated on good authority to have withstood more than six 

 thousand rounds, yet it is not unknown for several guns to be cast at the same 

 " pouring," from the same furnace, and in the same sandpit, yet some of these 

 guns shall stand 1500 or 2000 rounds, and others burst or otherwise give way, 

 at or under one-tenth of the number. Though offering, therefore, facilities in 

 boring and turning, and the advantage of being little chemically acted on by the 

 corroding and deflagrating action of the powder (so that its effect, only becomes 

 visible after perhaps 3000 rounds), or by tlie all-pervading chemical influence 

 of air and moisture, gun-metal would be well replaced with the cheaper and 

 more resistant wrought-iron, whenever means shall be obtained for working the 

 latter into the required forms with facility, and certainty of result. For many 

 years past field guns of cas^iron have been in satisfactory use by the Govern- 

 ments of Sweden and Denmark, and, it is said, of America. (Note O.) 



182. It was stated in foreign journals, in 1846, that Baron Hackewitz, at 

 Berlin, had perfected the means of forming bronze guns, by precipitation of the 

 alloying metals together in suitable moulds by the galvano-plastic process ; — 

 that the method had been found eminently successful, in escaping (by this, as it 

 were, humid gun-founding) all the difficulties of segregation of the metals and 

 want of homogeneity incidental to the ordinary methods by fusion ; — that a 

 commission, at the head of which was Humboldt, had been appointed by the 

 Prussian Ministry of War, to examine and report upon it, and that that Govern- 



