54 PHILOSOPHICAL TRANSACTIONS. [ANNO 17 QQ, 



heads of hatchets, and axes, or other chopping tools. And it is no small confirma- 

 tion of this opinion, that by analysis and synthesis we have found those metals to 

 contain, in perhaps most instances, the proportions of tin which renders them most 

 fit for the uses to which they were applied. This proportion being considered to be 

 about 1 part of tin to 9 parts of copper. 



Copper allayed with a larger proportion of tin than is generally contained in celt 

 metal ; that is, with £th or -fth of its weight of tin, is fitter for cutting instru- 

 ments, and piercing, boring, and drilling tools than celt metal ; because it is harder, 

 takes a finer edge, and yet is sufficiently strong on most occasions ; nor do we pos- 

 sess at this day any metal, that I know, which is so fit for knives, swords, daggers, 

 spears, drills, &c. as this allay, except iron and steel. The spear-head contains tin 

 in the very proportion here mentioned ; and if the metals had been pure, it would 

 perhaps not have been possible to have made this instrument of any other metals, 

 which were so proper, and at so small an expence. The sauce-pan also was made 

 of allay of copper by tin in the proportions last mentioned ; but as this instrument 

 is sufficiently hard with less or without any tin, there seems to be no use from the 

 addition of it. We may conjecture indeed, that as the sauce-pan was made of cast 

 metal, the tin was made for the purpose of rendering the copper more fusible, and 

 thus also for more easily casting forms of it. Perhaps also the tin was added to 

 render the copper less readily oxydable, and for the colour of this composition. 



Copper united with the proportions of tin last mentioned is very sonorous ; but 

 it is rendered much more so by still larger proportions of tin. I apprehend the 

 sonorous property increases as the proportion of tin is increased, within certain 

 limits ; provided the allay possess sufficient strength not to be fractured by the ne- 

 cessary impulse. But as the brittleness increases with the increased proportion of 

 tin, I believe not more than 1 part of tin is added to 3 parts of copper to compose 

 the most sonorous metal which is manufactured, namely, bell-metal.* But this 

 allay is too brittle to be beat out into a plate for making a trumpet; and accordingly 

 the lituus, which has been made of hammered metal, contains only about ] part of 

 tin and 7± parts of copper. 



Copper is united with tin for the purpose merely of becoming more fusible, and 

 of continuing longer fluid, or cooling more slowly while passing from the melted, 

 or fluid state, to the solid state. Such metal is used for making statues, and casts 

 of figures in general, and is called statuary metal,-}- and sometimes bronze. The 

 proportions of the 2 metals are various ; probably according to the colour proposed, 

 and the size and figure of the cast ; as well as on account of the price of the 

 metals. 



* The proportion of tin varies in bell-metal from -J. to -^th of the weight of the copper ; according to 

 the sound required, the size of the bell, and the impulse to be given. — Orig. 



•f The Greeks and Romans consumed vast quantities of copper in casts of figures. They added not 

 only tin but lead to the copper. The proportions given by Pliny are 1 part of a mixture of equal quanti- 

 ties of lead and tin to 15 parts of copper. The use of the lead I do not understand, if it was not to 

 save expence. — Orig. 



