The following experiments are taken without selection from the work of one student. Three experiments were made for each determination, and the mean result is given. By "range" is meant the difference between the highest and lowest result and the percentage loss is calculated on the silver present. The silver added in the lead used has been deducted.
Effect of Varying Lead.—In each experiment 0.4 gram of silver was taken and cupelled with the lead. The silver loss and "range" are expressed in milligrams.
| Lead Used. | Silver Lost. | Range. | Percentage Loss. |
| Grams. | |||
| 10 | 6.5 | 1.0 | 1.62 |
| 20 | 7.0 | 1.0 | 1.75 |
| 40 | 12.0 | 1.5 | 3.00 |
| 60 | 12.7 | 0.5 | 3.17 |
The loss increases with the lead used.
Effect of Varying Temperature.—0.4 gram of silver was cupelled with 20 grams of lead.
| Temperature. | Silver Lost. | Range. | Percentage Loss. |
| Bright red | 7.0 | 1.0 | 1.75 |
| Clear yellow | 17.3 | 1.7 | 4.32 |
The difference in temperature in these experiments was much greater than would occur even with careless work.
Effect of Varying Silver.—20 grams of lead were used in each cupellation.
| Silver Taken. | Silver Lost. | Range. | Percentage Loss. |
| Milligrams. | |||
| 12.5 | 0.7 | 0.2 | 5.6 |
| 25.0 | 1.4 | 0.1 | 5.6 |
| 50.0 | 1.6 | 0.4 | 3.2 |
| 100.0 | 2.9 | 0.3 | 2.9 |
| 200.0 | 5.6 | 0.5 | 2.8 |
| 400.0 | 7.0 | 1.0 | 1.7 |
| 800.0 | 9.7 | 1.0 | 1.2 |
It will be seen that, although the quantity of silver lost increases with the silver present, the percentage loss is greater on the smaller buttons.