74 ANNUAL OF SCIENTIFIC DISCOVERY. 



makes the aluminum bear about the same proportion in bulk as the tin 

 usually does, seemed much more promising. The alloy exceeds any bell- 

 metal in strength and toughness, and polishes like gold ; and as was men- 

 tioned in the lecture here on aluminum last year, it is superior to everything 

 except gold and platinum in its resistance to the tarnishing effects of the 

 air. This alloy would probably be an excellent material for watch wheels, 

 the reeds of organ pipes, and a multitude of other things for which brass is 

 now used a far weaker and more easily corroded metal, but as yet much 

 cheaper. But for all this, it will not stand for a moment against the old 

 copper and tin alloys for bells ; in fact, it is clearly the worst of all that 

 we have yet tried. Here is also a brass model for casting bells, which is of 

 course a brass bell itself, and that is better than the phosphorus and alumi- 

 num alloys, though inferior to bell-metal. (These were all exhibited.) So 

 much for the compound rnetals that have been tried as a substitute for bell- 

 metal. But we have now, through the kindness of M. Deville, of Paris, the 

 opportunity of realizing the anticipation formed from the sonorousness of a 

 bar of alluminum hung by a string, and struck. He has taken great pains 

 in casting a bell of this metal, from a drawing of our Westminster bell, re- 

 duced to six inches diameter. He has also turned the surface, which im- 

 proves the sound of small bells, where the small unevenesses of casting bear 

 a sensible proportion to the thickness of the metal, and in fact has done every- 

 thing to produce as perfect an aluminum bell as possible, though at its present 

 price it can hardly be regarded as more than a curiosity. But now for the 

 great question of its sound. I am afraid [ringing it] that it must be pro- 

 nounced to exceed all the others in badness, as much as it does in cost. I 

 cannot say I am much surprised ; indeed I did not expect it to be successful 

 as a bell, any more than silver, merely because a bar of it will ring. But it 

 was well worth while to try the experiment and settle it. Still the question 

 remains, what arc the best proportions for the copper and tin alloy, which 

 we are now quite sure, in some proportions, will give the strongest, clearest, 

 and best sound possible ? They have varied from something less than three 

 to something more than four of copper to one of tin, even disregarding the 

 bad bells of modern times, some of which contain no more than ten per 

 cent, of tin instead of from one fifth to one fourth, and no less than ten per 

 cent, of zinc, lead, and iron adulteration. Without going through the de- 

 tails of the various experiments, it will be sufficient to say that we found by 

 trial, what seemed probable enough before trial, that the best metal for this 

 purpose is that which has the highest specific gravity of all the mixtures of 

 copper and tin. It is clear, however, that the copper now smelted will not 

 carry so much tin as the old copper did without making the alloy too brittle 

 to be safely used. We found that the three to one alloy, even melted twice 

 over, had a conchoidal fracture like glass, and was very much more brittle 

 than twenty-two to seven twice melted, or seven to two once melted ; and 

 accordingly, the metal used for the Westminster bells is twenty-two to seven 

 twice melted ; or, reducing it for convenience of comparison to a percentage, 

 the tin is 24'1 of the alloy (not of the copper), and the copper 75-86. This 

 twenty-two to seven mixture, or even three and a half to one, which is prob- 



