Alcohol, 12.2.
Olive oil and aqueous alcohol (sp. g. .9231, tension of free surface
25.5), 6.8, angle 87 deg. 48'.
Quincke has determined the surface-tension of a great many substances
near their point of fusion or solidification. His method was that of
observing the form of a large drop standing on a plane surface. If K is
the height of the flat surface of the drop, and k that of the point
where its tangent plane is vertical, then
T = 1/2(K - k)^2 g[rho]
_Surface-Tensions of Liquids at their Point of Solidification. From
Quincke._
+--------------------+-----------------+----------+
| Substance. | Temperature of | Surface- |
| | Solidification. | Tension. |
+--------------------+-----------------+----------+
| Platinum | 2000 deg. C. | 1658 |
| Gold | 1200 deg. | 983 |
| Zinc | 360 deg. | 860 |
| Tin | 230 deg. | 587 |
| Mercury | -40 deg. | 577 |
| Lead | 330 deg. | 448 |
| Silver | 1000 deg. | 419 |
| Bismuth | 265 deg. | 382 |
| Potassium | 58 deg. | 364 |
| Sodium | 90 deg. | 253 |
| Antimony | 432 deg. | 244 |
| Borax | 1000 deg. | 212 |
| Carbonate of Soda | 1000 deg. | 206 |
| Chloride of Sodium | . . | 114 |
| Water | 0 deg. | 86.2 |
| Selenium | 217 deg. | 70.4 |
| Sulphur | 111 deg. | 41.3 |
| Phosphorus | 43 deg. | 41.1 |
| Wax | 68 deg. | 33.4 |
+--------------------+-----------------+----------+
Quincke finds that for several series of substances the surface-tension
is nearly proportional to the density, so that if we call (K - k)^2 =
2T/g[rho] the specific cohesion, we may state the general results of
his experiments as follows:--
The bromides and iodides have a specific cohesion about half that of
mercury. The nitrates, chlorides, sugars and fats, as also the metals
lead, bismuth and antimony, have a specific cohesion nearly equal to
that of mercury. Water, the carbonates and sulphates, and probably
phosphates, and the metals platinum, gold, silver, cadmium, tin and
copper have a
|