OF RADIANT HEAT THROUGH DIFFERENT BODIES. 



23 



oil of colza*, and after having waited until the needle recovered its ori- 

 ginal position we reestablished the calorific communication. 



The deviations obtained through the different thicknesses of the li- 

 quid are exhibited in the following table. 



Degrees of thickness of Deviations of the galva- 



the liquid layer. 



6-767 

 13-535 

 27-069 

 54.-139 

 81-209 

 108-279 



nometer. 



15-64-2 



12-831 



10-389 



9-54.0 



8-988 

 8-512 



The free radiation being always represented by 1000, the respective 

 quantities of the rays transmitted and those stopped are found to be : 



Degrees of thickness of 

 tlie liquid layer, 

 mm 



6-767- 

 13-535 

 27-069 

 54-139 

 71-209 

 108-279 



Table B. 

 Rays transmitted. 



U3 

 363 

 294 

 270 

 255 

 244 



Rays stopped. 



557 

 637 

 706 

 730 

 745 

 756 



If we suppose the last layer (of 108'"™-274) subdivided into six paral- 

 lel slices of the following degrees of thickness : 6"'"'-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 pEissage. 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 : 



Losses in the respective transmissions 

 referred to the quantities of 

 rays which arrive at the 

 surface of each slice. 



Degrees of thickness of the six 



successive slices into wliich 



we suppose the layer of 



108°""-274 to be divided. 



ram 



6-767 



6-767 

 13-535 

 27-069 

 27-069 

 27-069 



0-557 

 0-180 

 0-190 

 0-082 

 0-056 

 0-040 



[* It may be proper to inform the English reader that "oil of colza" is an oil 

 expressed from the seeds oilhcC/ioiiCoka of the French, Brasska arveiixis, Linn. 

 It nuist not be confounded with the rape oil of England, obtained from the Rape, 

 Brasska Napus. — Edit.] 



