In the above specimens no crystallis detected.

The tensile strength of copper-zinc alloys gent; the greatest strength, according to M in the alloy containing 32.85 per cent cop very probably a mistake, and the greatest alloys containing upwards of 50 per cent cop

§ 24. The following table of the compo perties of copper-zinc alloys is taken from M and Karsten's observations 1

1 Percy's Metallurgy, p. 611.

"Remarks on the preceding Table.-The figure column 6 represent intensity of tint of the same colour. column 7 the letters are abbreviations for the character the fractures according to Mallet's nomenclature, thus

fine-fibrous, C. conchoidal, V.C. vitreous fine-crystalline, C.C. coarse-crystalline. Th was determined on prisms inch squar been hammered or compressed after bei weights given are those which each prism ju few seconds before disruption.

"6. Approaching tombac in colour, is n for rolling, hammering, or wire drawing as c which contains less copper in proportion to

"8. Comes very near 'red-brass,' which with respect to its working qualities.

"10. The reddish colour is now beginn brass-yellow; it behaves itself irreproachabl and hammer, and in wire drawing.

"13. Working qualities quite the same a mon brass. Karsten remarks that it was this puffed for some time in England under the gold.

“14. In working qualities not different brass.

"16. It contains 4 per cent more zinc and copper than common brass. The colour is brass-yellow, but has a reddish tint, works ex the rolls and hammer, as well as in wire drav

"19. Much to be recommended, on accou colour, and though it possesses greater ten preceding, and less hardness, is brittle. W cast ware. Very flexible after casting w When cold it is hard to cut, and is rather frac The ingots after being cut, annealed, and longer be rolled. If, after heating and temperature of boiling water, they are rolled only very brittle, fragile sheets, much cracked notwithstanding that frequent annealing duri have been resorted to; it is quite unsuitab hammering, or wire drawing.

"20. Very flexible while strongly heated.

well cold, though it frequently cracks at the edges. D rolling into thin sheets, it requires more frequent ann than common brass. It cannot be soldered, as it me the same temperature as the solder. It is not adapt wire drawing.

"21. Fracture reticulated. Possesses a tolerable d of tenacity, but by hammering becomes so brittle that temperature can it be sufficiently drawn out for pra purposes.

"22. The lustre is so imperfectly metallic, that it hardly be recognised as a metallic alloy. Its great britt and frangibility, combined with its perfectly conchoida smooth fracture, communicate to the alloy more the a ance of a sulphur compound than that of a mixture o metals.

"23. More brittle than the last; fracture smooth, small-conchoidal; lustre strongly metallic.

"25, 26, 27. Very brittle. Too hard to file or lustre nearly equal to that of speculum metal.

"28, 29. Brittle. Too hard to file or turn; lustre equal to that of speculum metal.

"30. Very brittle. Too hard to file or turn; lustre equal to that of speculum metal.

"31. Barely malleable.

"32. Brittle; fracture granular, uneven ; has a tol degree of tenacity, but cannot be worked under the r hammer.

"33. Brittle.

"34. In external character and working qualities resembles No. 32.

"36. Brittle.

"38. Fracture finely granular.

"39. Has sufficient tenacity to admit of being som extended under the rolls and hammer, if, after annealing not allowed to become cold."