224 



REPORTS ON THE STATE OF SCIENCE. 



The difference between the loss to the polished and blackened surfaces 

 represents the greater part of the radiation from the gas. There is reason 

 to suppose, however, that it does not represent the whole, because it is 



OS$ 



Fig. 6. 



probable that at an early stage in the cooling with the polished walls 

 the bright surface of the silver is dimmed by a deposit of moisture. 1 



Finally, a series of records have been taken with a bolometer placed 

 outside the explosion vessel altogether, but exposed to the radiation of 

 the flame through a window of fluorite (fig. 7). This bolometer was 

 of platinum blackened with lamp-black, and the records were taken in 

 exactly the same way as in the other cases. A facsimile of one such 

 record is given in fig. 6, and the Table IT. shows the amounts of 

 heat absorbed by this bolometer at different times. 



Table II. 



1 The possible importance of such a deposit was suggested to me by Mr. W. T, 

 David, who carried out all the experiments described in this note. 



