49 ON THE ALLOYS OF COPPER AND ZINC. 
Per cent Per cent 
Number Per cent of Per cent of Copper found Number Per cent of Per cent of Copper found 
of the Copper put into | of Copper found | in the portion of the Copper put into | of Copper found | in the portion 
Experiment. the Alloy. in the Crystals. of Alloy Experiment. the Alloy. in the Crystals. of Alloy 
poured off. poured off. 
X 97.38 99.14 98.68 21* 62.30 
2 96.50 95.57 97.40 22 60.29 61.16 61.99 
3 94.38 95.06 95.04 231 60.92 61.36 
4 94.38 94.30 93.82 24T 60.77 60.88 
5 91.38 90.77 91.49 251 60.42 60.24 
6 88.38 88.86 88.78 — 26 56.69 57.82 58.66 
7 85.38 86.10 85.74 27 53.09 54.22 54.45 
8 79.38 83.72 83.61 28 51.00 52.62 52.11 
9 82.38 82.89 82.52 29 49.00 49.51 49.55 
10 79.38 80.34 80.73 30 47.00 49.43 48.26 
11 76.38 77.32 78.92 31 45.00 47.49 46.79 
12 73.38 75.03 74.27 32 43.00 44.41 43.63 
13 74.38 75.71 14.94 33* 43.64 44.01 
14 72.38 74.52 73.61 34 41.00 41.48 42.19 
15 70.00 71.48 71.68 85 39.00 88.57 38.77 
16* 69.20 36 37.00 . 38.09 37.71 
17 67.40 68.93 67.37 37 35.00 35.33 36.71 
18 65.94 67.12 38 33.00 32.98 32.79 
199 66.94 39 27.31 29.67 29.07 
20* 65.56 40* 29.07 
In determining the amounts of copper contained in these alloys I have employed 
a method which has been used for a long time by many of the copper assayers 
of this country, by whom it is highly esteemed. It is essentially the old Swedish 
method $ of precipitating the copper from its solution in acid, by means of metallic 
iron; with, however, several more modern modifications and improvements.|| Since 
several of the details of this process have never, to my knowledge, appeared in 
chemical literature, I shall make no apology for describing it at length in this 
connection, 
In choosing samples of the alloy for analysis, I have been careful to select those 
portions of the cup which were best crystallized, avoiding always the upper crust, 
* The instances in which the amounts of metal used in preparing the alloy are not given, refer to crystal- 
lized products which were obtained accidentally during the course of the research. 
T Yellow-metal from founder’s pots, said, from appearance of test ingot, to require a little more zinc. 
i Yellow-metal which had afforded a satisfactory test. : 
$ Vid. Bergman, Physical and Chemical Essays, translated from the olifindr Latin by E. Cullen, 
M. D., (London, 1788,) Vol. II. p. 443. Described more fully by Kersten, in Karsten u. von Dechen's 
Archiv für Mineralogie, u. s. w., XIL 567; also by Kerl in Bodemann's Probirkunst von Bruno Kerl, 
(Clausthal, 1857,) S. 216. 
| For information concerning these I am indebted to Mr. G. J. Dickinson, chemist of the copper 
works at Point Pose near Boston. 
