oil of colza[1], and after having waited until the needle recovered its original position we reestablished the calorific communication.
The deviations obtained through the different thicknesses of the liquid are exhibited in the following table.
| Degrees of thickness of the liquid layer. |
Deviations of the galvanometer. | ||
| mm | ° | ||
| 6 | ·767 | 15 | ·642 |
| 13 | ·535 | 12 | ·831 |
| 27 | ·069 | 10 | ·389 |
| 54 | ·139 | 9 | ·540 |
| 81 | ·209 | 8 | ·988 |
| 108 | ·279 | 8 | ·512 |
The free radiation being always represented by 1000, the respective quantities of the rays transmitted and those stopped are found to be:
| Table B. | |||
| Degrees of thickness of the liquid layer, |
Rays transmitted. | Rays stopped. | |
| mm | |||
| 6 | ·767 | 443 | 557 |
| 13 | ·535 | 363 | 637 |
| 27 | ·069 | 294 | 706 |
| 54 | ·139 | 270 | 730 |
| 71 | ·209 | 255 | 745 |
| 108 | ·279 | 244 | 756 |
If we suppose the last layer (of 108mm·274) subdivided into six parallel slices of the following degrees of thickness: 6mm·767, 6·767, 13·535, 27·069, 27·069, and 27·069, we shall be able to determine, by means of the numbers contained in the two last columns, the quantity of heat incident to the first surface of each of these slices and the quantity lost in the passage. Dividing the second by the first we shall ascertain the loss. It is unnecessary to exhibit the operations in detail, as they are in all respects similar to those which have been performed in reference to the screens of glass. Here are the final results:
| Degrees of thickness of the six successive slices into which we suppose the layer of 108mm·274 to be divided. |
Losses in the respective transmissions referred to the quantities of rays which arrive at the surface of each slice. | ||
| mm | |||
| 6 | ·767 | 0 | .557 |
| 6 | ·767 | 0 | ·180 |
| 13 | ·535 | 0 | ·190 |
| 27 | ·069 | 0 | ·082 |
| 27 | ·069 | 0 | ·056 |
| 27 | ·069 | 0 | ·040 |
- ↑ [It may be proper to inform the English reader that "oil of colza" is an oil expressed from the seeds of the Chou Colza of the French, Brassica arvensis, Linn. It must not be confounded with the rape oil of England, obtained from the Rape, Brassica Napus.—Edit.]
