' 
ON MANGANESE BRONZE. 385 
Another, and perhaps still more palpable proof of the value of com- 
bining the metals in their atomic proportions is that, when this is done, 
the specific gravity of these alloys is perceptibly increased over those not so 
combined, even though in the latter case the heavier metal be in excess. 
I was much struck by this fact in taking the specific gravity of some 
No. 1 manganese bronze, which contains a considerable amount of zinc, and 
which, judging by its constituents, ought to be a comparatively light metal ; 
but the trial proved that it was about equal to that of ordinary gun-metal, 
composed of copper and tin, and very considerably above the mean weight 
of the metals composing it, indicating to my mind that these metals must 
have combined in such a manner as each to fit into, and more nearly fill 
up, the infinitesimal spaces between the atoms of the other, and if not 
actually forming what chemists would admit to be a perfect chemical 
combination, certainly more nearly approaching it than when the metals 
are mixed together in the haphazard manner usually prevailing. 
I have no doubt that these combinations and the stable quality of the 
manganese bronze alloys is due also very materially to the action of the 
metallic manganese on the copper, by freeing it from the oxides it contains 
and bringing the metals added to it into actual contact, and thus enabling 
them to combine in a more perfect manner than has been accomplished 
hitherto. I have only now to refer to the list of tests appended, which it 
would be tedious to recite; but they can be referred to, and the results 
will be found attached to the samples, as also a description of the other 
articles exhibited. 
Tests or MANGANESE Bronze. 
By Tensile Strain. 
Elastic Break- Ulti- 
Refer- | Limit | ,i@&, | mate 
Descrip- Where : Tons, | Strain | Elonga- R a 
tion Tested ence ons. | Tons. tion. SUITS 
Number} Per sq-} “po, Per 
Rh. G. F. 6,536 | 11:00 | 29°00 | 446 | Mild for riveting cold 
Fa 
3 and annealed. 
en Ui d8: 5,060 | 13:17 | 29:29 | 33-4 | Annealed. 
53) | Do. 4,995 | 23-54 | 31:60 | 26°5 As delivered from the 
go Do. 4,996 | 24:32 | 31-43 | 23:3 rolls hot. 
7 a Re Gs Be. 6,547 | 34:40 | 39°60 | 11:6 | Ditto and finished cold. 
Bun | BRG.F. | 7,365 | 1406 | 28-46 | 23-2 | Pulled across fibre. ) 3 
oo3 Do. 7,369 | 1406 | 3013] 47:8 » withfibre. [3 
dos Do. 7,372 | 14:80 | 30°78 | 34:1 s» across fibre. { 3 
2 ma Do. 7,374 | 16:70 | 30°10 | 28-8 » with fibre. JZ 
BS 3 |M.B.&B.Co| 1 18:00 | 35°00 | 22:0 | Cast in an iron cylinder 
= = Do. 2 16:23 | 31:90 | 12-4 and pressed while 
Ba liquid. 
a » oO 
$25, 
Zo 
No. 1 cut from side of ingot and No. 2 from centre. 
18838. cc 
