The following is a table of the proportions of the various metals in the alloys most commonly employed in the arts and manufactures. The term "parts" means parts by weight. The abbreviations are: Cu, copper; Zn, zinc; Sn, tin; Pb, lead; Sb, antimony; P, phosphorus; As, arsenie; Ni, nickel.

Description.

Cu.

Zn.

Sn.

Pb.

Sb.

P.

As.

NL

Metal for frictional parts of loco-) motives (extremelyhard) ......

87

5

8

• •

• •

• •

• •

• •

Bearings of carriages.......

97

3

• •

• •

• •

• •

• •

• •

Bearings of driving wheels, also for) steam-engine whistles giving a clear) sound.........

80

2

18

• •

• •

• •

• •

• •

Steam-engine whistles giving a deep) sound.....

81

2

17

• •

• •

• •

• •

• •

Cross-heads of connecting-rods.....

82

2

16

• •

• •

• •

• •

• •

Cylinders of pumps, valve-boxes, and ) taps ........

88

2

10

• •

• •

• •

• •

• •

Eccentric collars ............

84

2

14

• •

• •

• •

• •

• •

Bearings of axles and trunnions; eccentric collars........

84

2

14

• •

• •

• •

• •

• •

85

2

13

• •

• •

• •

• •

• •

84

7

9

• •

• •

• •

• •

• •

68

4

28

• •

• •

• •

• •

• •

Pistons of locomotives..........

88

9

3.

• •

• •

• •

• •

• •

84

8.4

2.9

47

• •

• •

• •

• •

Axle-boxes...........

88

2

10

• •

• •

• •

• •

• •

Mathematical instruments, arms of balances............

90

2

8

• •

• •

• •

• •

• •

Machinery,bearing,etc.

67

• •

14

19

• •

• •

• •

• •

Steam-engine whistles........

30

• •

18

• •

2

• •

• •

• •

Metal to withstand friction (Stephenson)....

79

5

8

8

• •

• •

• •

• •

Rivets........

64

24.6

3

9

• •

• •

• •

• •

Metal for coffins......

15

• •

40

45

• •

• •

• •

• •

Metal to withstand friction.......

2

• •

72

••

26

• •

• •

• •

Cylinders of pumps.........

7

72

21

• •

••

• •

• •

• •

Metal for bearings of locomotives

2

• •

90

• •

8

• •

• •

• •

White brittle metal (for buttons, etc.)

10

6

20

• •

64

• •

• *

Imitation silver.........

64

• •

3

• •

• •

• •

• •

• •

Pinchbeck.........

5

1

• •

• •

• •

• •

• •

• •

Tomba..........

16

1

1

• •

• •

• •

• •

• •

Red tombac..........

10

1

• •

• •

• •

• •

• •

• •

Description.

Cu.

Zn.

Sn.

Pb.

Sb.

P.

As.

N1.

Specially adapted for bearings.....

83

• •

15.5

• •

1.5

• •

• •

• •

For bearings and valves.......

83.25

• •

7

9

• •

.75

• •

• •

Electrotype " backing metal".....

• •

• •

4

91

5

• •

• •

• •

Stereotype metal for paper process

• •

• •

• •

88

1.2

• •

• •

• •

,, „ for plaster process..

• •

• •

• •

82

18

• •

• •

• •

Ballet metal......

• •

• •

• •

92

• •

• •

2

• •

Malleable brass plate.......

67

33

• •

•5

• •

• •

• •

• •

Fin wire........

67

33

•5

•5

• •

• •

• •

• •

Jemmapes brass........

64.6

33.7

•2

1.5

• •

• •

• •

• •

Similor for gilding........

92.7

4.6

2.7

• •

• •

• •

• •

• •

Maillechort for rolling........

60

20

• •

• •

• •

• •

• •

20

„ first quality.......

8

3

• •

• •

• •

• •

4

White similor....

7

• •

• •

• •

• •

• •

•5

• •

For stopcock seats......

• •

• •

86

• •

14

• •

• •

• •

. „ plugs.....

• •

• •

80

• •

20

• •

• •

• •

For keys of flutes, etc.....

• •

• •

• •

20

40

• •

• •

• •

Hard tin.........

••

• •

1

• •

0.5

• •

• •

• •

White tombac......

75

• •

25

• •

• •

• •

• •

• •

Vogel's alloy for polishing steel

8

1

2

1

• •

• •

• •

• •

Rompels anti-friction metal ...

62

10

10

18

• •

• •

• •

• •

Arguzoid, a tough alloy superior to brass............

56

23

4

3 1/2

• •

• •

• •

13 1/2

The proportions of the several ingredients in the various alloys given above must be regarded as only approximative in many cases. Every manufacturer adopts the proportions which experience has taught him to be the most suitable for the purposes for which the alloy will be used, or perhaps, in some instances, which accident or caprice first led him to make use of. Half a dozen samples of that variety of pewter known as Britannia metal, from as many different manufacturers, would probably prove widely different in their composition, though similar in appearance, and applicable to the same uses. The same remark holds good of such alloys as pinchbeck, tombac, Mannheim gold, and some others. More than this, even the products of the same manufactory may vary considerably in composition at different times, when these products are not required to possess in a high degree any given quality. It is, therefore, not surprising that the proportions published in many works are so different and con-tradictory. Thus we hare, for example, one acknowledged authority giving the composition of Britannia metal as equal parts of brass, tin, antimony, and bismuth; while another gives the composition as 150 parts of tin, 3 parts of copper, and 10 parts of antimony, omitting the bismuth altogether.

It would be easy to find a third authority giving a composition of this alloy widely different from the above two. From out of this chaos it is impossible to evolve anything like order, or to give information that shall not be at variance with all that has preceded it from sources acknowledged to be trustworthy. Hence the recipes given must be regarded as having only an approximate value generally, though for the cases in view they are exact, ie, they are the proportions which have been actually adopted in practice. Many of them have been ascertained by analysis of the finished product, while others have been obtained from sources that are worthy of confidence.

A number of ancient alloys examined by W. Flight showed the following compositions:-(1) Bactrian coins, about 230 B.O., contained 77 per cent. copper, 20 nickel, and smaller quantities of cobalt and iron. (2) Square Indian coins, 500 B.C., 89 per cent. silver, 4 copper, 4 lead, with silver chloride, gold, and graphite. (3) A figure of Buddha, 57 per cent. silver, 4 silver chloride, 37 copper, with gold and graphite. (4) Boxes or bowls of Bidrai ware, Secunderabad, India, 94 per cent. zinc, 4 copper, 1 1/2 lead, into the surface of which thin sheet silver is inlaid. (8) Double hook of bronze found in an air passage of the Great Pyramid, 99 1/2 per cent. copper. (9) Bronze figures brought from Egypt by John Dixon, supposed to be of Ptolemaic origin: a figure of Isis, 68.4 per cent. copper, 4.7 iron, 22*7 lead, 1*5 arsenic, 0.9 tin, with traces of nickel and antimony; another bronze. 82.2 per cent. copper, 15.8 lead, 2 tin. (13) Various Cypriote, Roman, and Greek bronzes, 78 to 87 per cent. copper, 8.5 to 10.9 tin, and 1*5 to 9 lead. (14) Inca pin, from a mummy at Arica, 82 per cent. silver, 1.4 silver chloride, 16.1' copper. (15) Bronze bar from temple in Bolivia, 93*2 per cent. copper, 6.5 tin.

Kalischer, of Berlin, recently made an analysis of four Japanese alloys, with the following results:-

a

b

Copper

• •

• •

95.77

..

51.10

Silver

• •

• •

0.08

..

48.93

Gold..

..

..

4.16

..

0.12

c

d

Copper

..

..

76.60

• •

76.53

Lead

..

..

..

11.88

• •

12.29

Zinc

..

..

..

6.53

• •

6.68

Tin

..

..

..

4.38

• •

4.36

Iron

..

..

..

0.47

• •

0.34

The first, which contained much gold, had a light-red colour, with a bluish-black, lustrous patina on one side. The second, which contained silver, had a grey, almost silver-white colour, with a slight shade of yellow. c and d resembled brass in colour, and were, as the figures show, almost identical, representing a peculiar kind of bronze. Externally they were exactly alike, except that one had a fine crust outside which gave it a duller look than the metal itself. They differ from bronze in having so much lead in them, and the amount of zinc is also higher.

H. Morin published analyses of some Chinese and Japanese bronze exhibited at Paris in 1867; like c and d above, they are distinguished by the large percentage of lead, which he found to vary between 9.9 and 20.31 per cent., while the zinc fluctuated from 0.5 to 6.0 per cent. To the large amount of lead Morin attributes the black patina which mostly characterises these bronzes. Gristofle and Bouilhet, on the one hand, confirm this view, and, on the other, prove that patina of different colours may be produced by chemical means without having recourse to bronze containing a large quantity of lead, which, as Morin himself states, is difficult to use on account of its brittleness. Morin's analyses show that in other respects the bronzes he examined bear no relation to those analysed by Kalischer.

In 1866 R. Pumpelly published the composition of a number of Japanese alloys, which showed the greatest conformity with the above, especially the two first mentioned. A native worker in metals allowed Pumpelly a glance into the preparation of the metals, which is generally kept secret, and he described, under the name of shahdo, alloys of copper and gold in which the quantity of gold varied from 1 to 10 per cent. They have a bluish-black patina, which is produced by boiling the metal or the object made of it in a solution of copper sulphate, alum, and verdigris, which removes some of the copper and exposes a thin film of gold. The action of light upon this produces the bluish-black colour, the intensity of which increases with the quantity of gold. This group can be reckoned with alloy a above. Gin-shi-bui-chi is an alloy of silver and copper, in which the amount of silver varies between 30 and 50 per cent. When boiled in the above solution, the alloy acquires a grey colour much admired by the Japanese. Alloy b belongs to this group.