The admirable bronzes of China and Japan are well known in the English market, and Raphael Pumpelly,[279] who studied direct from the native workmen, has printed interesting notes on the ornamental alloys, or Mokume, applied to Swords and other articles. Damask-work is produced by soldering alternately thirty to forty sheets of rose-copper, silver, shakdo (copper one to gold ten per cent.), and gui shi bu ichi (silver and copper). The mass is then cut into deep patterns with the reamer. An alloy of silver (thirty to fifty per cent. of copper) produces the favourite tint, a rich grey colour, and this becomes a bluish black like niello by being boiled after polishing in a solution of sulphate of copper, alum, and verdigris. Dr. Percy (p. 340) describes the liquation of argentiferous copper in Japan.[280]
We owe to Dr. George Pearson[281] sundry experiments in alloys, which first determined that the norm of the Old World and the best proportion for weapons and tools are one tin to nine copper.
Fusing the metals, he found:
1 tin : 20 copper (5 per cent.) produces a dark-coloured bronze with the red fracture of the pure metal.
1 tin : 15 (6½ per cent.) gives a stronger alloy and obliterates the colour.
1 tin : 12, 9, 8, 7, 6, 5, 4, 3 gradually increases hardness and brittleness.
1 tin : 2 makes a mixture almost as brittle as glass.
The following table[282] shows the alloys now in common use, and the purposes to which they are applied:
| Tin | Copper | Per cent. Copper | |||
|---|---|---|---|---|---|
| 11 | 108 | = | 90·76 | Cannon, statues, machine brasses. | |
| 11 | 99 | = | 90 | ‘Gun-metal’ proper (cannon). | |
| 11 | 84 | = | 84·44 | ‘Gun-metal,’ machinery bearings. | |
| 11 | 72 | = | 86·75 | Harder composition. | |
| 11 | 60 | = | 84·50 | Not malleable. | |
| 11 | 44 | = | 80 | Cymbals, Chinese gongs. | |
| 11 | 48 | = | 81·35 | Very hard, culinary vessels. | |
| 11 12 | 36 36 | } = { | 76·69 75·00 | } | ‘Bell-metal.’ |
| 11 | 24 | = | 68·57 | Yellowish, very hard, sonorous. | |
| 11 | 4 | = | 26·6 | Very white,[283] specula.[284] |
The most popular alloy of copper, next to bronze, is brass, which is harder and wears better than the pure metal. Originally, as now, it was a mixture of copper and zinc, popularly called spelter (old speautre, speauter, spiauter, spialter).[285] The proportions greatly varied, one part of the latter to two of the former being the older ratio, and the density increasing with the amount of copper from 8·39 to 8·56.