Hardness of Metals and AUuijs. 



119 



On Bronze Alloys. 



Formulae of alloys and per-centages. 



Weight 

 employed. 



CuSnS 

 Cu Sii" 

 CuSnS 

 CuSn2 

 CuSn 

 Sn Cu= 

 Sn Cu3 

 SnCu< 

 SnCu5 

 Sn Cu»o 

 Sn Cu'5 

 Sn Cu^o 

 SnCu25 



fCu 9731 



ISn 90-27/ 



rCu 11-861 



ISn 88-14/ 



rCu 15-211 



ISn 84-79/ 



/Cu21-2n 



ISn 78-79/ 



rCu 34-98 1 / 



tSn 65-02/ \ 



rCu48-171 / 



lSn51-83/ 1 



/Cu 61-79 \ / 



tSn 38-21/ \ 



J Cu 68-27 1 / 



tSn31-73/ \ 



J Cu 72-90 1 



lSn27-10/ 



/ Cu 84-32 1 



ISn 15-68/ 



/ Cu 88-97 1 



tSnll-03/ 



/Cu 91-49 I 



ISn 8-51/ 



/Cu 93-171 



"[Sn 6-83/ 



lbs. 



400 

 460 

 500 

 650 



Obtained, 

 cast iron 

 = 1000. 



83-33 



95-81 



104-17 



135-42 



Calculated, 

 cast iron 

 = 1000. 



51-67 

 59-56 

 68-75 



84-79 



At 700 lbs. the point entered one-half, and 



the alloy broke. 

 At 800 lbs. the alloy broke without the 



point entering. 

 At 800 lbs. the aUoy broke into small pieces 



(blue alloy). 

 1300 lbs. divided the alloy into two pieces 

 without the point having entered 1 niiUim. 



The same as the preceding. 



4400 

 3710 

 3070 

 2890 



916-66 

 772-92 

 63958 

 602-08 



257-08 

 270-83 

 277-70 

 279-16 



The results obtained from this series of alloys lead to several 

 conclusions deserving our notice. First, the marked softness of 

 all the alloys containing an excess of tin ; secondly, the extraor- 

 dinary fact that an increased quantity of so malleable a metal as 

 copper should so suddenly render the alloy brittle, for the 

 "^ Alloy Cu Sn^ 



or 



Copper 21-211 • f i *.! 



Tin 78-79/ i« "«* brittle, 



whilst the alloy Cu Sn 

 or 



Copper 34-981 • . 



Tin 65-02 J '^ *^""^^- 



Therefore the addition of 14 per cent, of copper renders a bronze 

 alloy brittle. This curious fact is observed in all the alloys with 

 excess of copper, Sn Cu^, Sn Cu^, Sn Cu'', Sn Cu'^, until we arrive 

 at one containing a great excess of copper, viz. the alloy Sn Cu'°, 

 consisting of copper 84*08, and tin 15-32, when the brittleness 

 ceases ; but, strange to say, this alloy, which contains four-fifths 



