Hardness of Solders.
—According to the before-mentioned authority, Saposhniko, in 1908, determined the hardness of various lead-tin alloys by Brineli’s method, by which a steel cone is forced into the metal. The results he obtained are as follow:
| Lead | 100 | 90 | 80 | 70 | 60 | 50 | 40 | 34 | 33 | 32 | 30 | 20 | 10 | 0 |
| Tin | 0 | 10 | 20 | 30 | 40 | 50 | 60 | 66 | 67 | 68 | 70 | 80 | 90 | 100 |
| Hardness | 3·9 | 10·1 | 12·16 | 14·5 | 15·8 | 15·0 | 14·6 | 16·7 | 15·4 | 14·6 | 15·8 | 15·2 | 13·3 | 4·1 |
These results, says Mr. Hiorns, show that the hardest alloy is the one with 66% (about 2 parts) of tin and 34% (about 1 part) of lead, which also is the one having the lowest melting point of all the lead-tin alloys. The results also show that tin is slightly harder than lead.