Comp. The following Table exhibits the composition of the more important compounds of this class:—
Table of the principal Alloys.[27]
| Names. | Combining metals. |
| Albata | See German Silver. |
| Amalgams | Mercury and other metals. |
| Bath-metal | Copper and zinc. |
| Bell-metal | Copper and tin. |
| Brass | Copper and zinc. |
| Britannia metal | Tin with antimony, copper, and bismuth. |
| Bronze | Tin and copper. |
| Bronze aluminium | Copper and aluminium. |
| Cannon-metal | Tin and copper. |
| Dutch gold | Copper and zinc. |
| Fusible metal | Bismuth, lead, and tin. |
| German silver | Copper, nickel, and zinc, with, sometimes, a little iron and tin. |
| Gold (standard) | Gold with copper. |
| Gold (old standard) | Gold with copper and silver. |
| Gun-metal | See Cannon-metal. |
| Mosaic gold | Copper and zinc. |
| Or-molu | Copper and zinc. |
| Pewter (common) | Tin and lead. |
| Pewter (best) | Tin with antimony, bismuth and copper. |
| Pot-metal, Cock-metal | Copper and lead, with, sometimes, a little zinc. |
| Queen’s metal | Tin with antimony, bismuth, and copper. |
| Shot-metal | Lead with a little arsenic. |
| Silver (standard) | Silver and copper. |
| Solder | Tin and lead. |
| Speculum-metal | Tin and copper, and arsenic. |
| Stereotype-metal | Lead, antimony, and bismuth. |
| Tombac, Red Tombac | Copper and zinc. |
| Tutania | See Britannia metal. |
| Type-metal | Lead and antimony. |
| White copper (Packfong; Whitetombac) | Copper and arsenic. |
[27] For the proportions of the component metals, refer to the alloys under their respective heads.
Prop., &c. Alloys generally possess characteristics unshared by their component metals. Thus, copper and zinc form brass, which has a different density, hardness, and colour to either of its constituents. Whether the metals tend to unite in atomic proportions, or in any definite ratio, is still undetermined. The evidence afforded by the natural alloys of gold and silver, and by the phenomena accompanying the cooling of several alloys from the state of fusion, goes far to prove that such is the case. (Rudberg.) The subject is, however, one of considerable difficulty, as metals and metallic compounds are generally soluble in each other, and unite by a simple fusion and contact. That they do not combine indifferently with each other, but exercise a species of elective affinity not dissimilar to other bodies, is clearly shown by the homogeneity and superior quality of many alloys in which the constituent metals are in atomic proportions. The variation of the specific gravity and melting-points of alloys from the mean of those of their component metals, also affords strong evidence of a chemical change having taken place. Thus, alloys generally melt at lower temperatures than those required for their separate metals. They also usually possess more tenacity and hardness than the mean of their constituents.
Matthiessen found that when weights are suspend to spirals of hard-drawn wire made of copper, silver, gold, or platinum, they become nearly straightened when stretched by a moderate weight; but wires of equal dimensions
composed of copper-tin (12% of tin), silver-platinum (36% of platinum), and gold-copper (84% of copper), scarcely undergo any permanent change in form when subjected to tension by the same weight.
The same chemist gives the following approximative results upon the tenacity of certain metals and wires hard drawn through the same gauge (No. 23):
Breaking strain for:
| lbs. | ||
| Copper | 25-30 | |
| Tin | under | 7 |
| Lead | ” | 7 |
| Tin-lead (20% lead) | about | 7 |
| Tin-copper (12% copper) | ” | 7 |
| Copper-tin (12% tin) | ” | 80-90 |
| Gold | 20-25 | |
| Gold-copper (8·4% copper) | 70-75 | |
| Silver | 45-50 | |
| Platinum | 45-50 | |
| Silver-platinum (30% platinum) | 75-80 |