150 Scientific Intelligence. [Aug. 



prived of access to any other earth except strontian, after a time 

 began to lay eggs destitute of an earthy shell. 



The origin of phosphoric acid was also noticed; this may be sus- 

 pected to be an organic product. 



Mr. Tvviss made some remarks on the papyri, especially with 

 regard to the claims of the Padre Anto^. Piaggio to inventing the 

 mode of unrolling them. These he considered well founded, and 

 that Sir H. Davy only improved upon the process by suggesting the 

 use of alcohol to soften the rolls. They were sometimes soaked in 

 ether. The ink is made of carbon mixed with some glutinous matter : 

 hence probably the ammonia, sometimes found to be present. It is a 

 question whether the papyri were actually carbonized by the action 

 of fire. Sir H. Davy supposed it the effect of hot water. 



Dr. Daubeny observed that long continued moisture alone would 

 suffice to carbonize and blacken a vegetable substance. 



Mr. Powell made some remarks on the recent researches of 

 M. Melloni on radiant heat, of the second portion of whose Memoir 

 he has recently received a copy. He referred more particularly to one 

 point, viz. the repetition of his own experiment by Melloni, with his 

 extremely delicate apparatus, and fully verifying his results. But 

 M. JMelloni appears to view the subject under a different aspect, and 

 to adopt a different theory. This renders the confirmation of the 

 fact the more satisfactory. 



If the experiment be substantial, it appears to the author that his 

 conclusion follows by necessary consequence. M. Melloni adopts 

 the theory that the heat by passing through the glass screen 

 acquires a new property, or new relation to the surfaces of bodies on 

 which it acts ; an hypothesis which is at variance with all analogy. 



In the Philos. Trans. 1825, the author's paper appeared, in which 

 he maintained (in opposition to the theory of De La Roche) that 

 from a luminous hot body there emanate at the same time two dis- 

 tinct sorts, or causes, of heat, distinguished by different properties. 



This was evinced by experiments, in which the ratio of the effects 

 on two thermometers, one coated with a black, the other with a 

 white substance, (but very absorptive for simple heat,) was observed 

 first with, and then without, the interposition of a glass screen. With 

 the screen the absolute effects were of course diminished : but the 

 remarkable circumstance was, they were in a different ratio. 



Of the accuracy of this experiment, it would seem that some doubt 

 must have existed in the minds of those writers who have since treated 

 the subject, since they either omit to refer to it, or, what is more 

 extraordinary, adopt it along with the theory which it contradicts. 



It is possible that the nature of the reasoning may have been mis- 

 understood, from having been too briefly stated. It may perhaps 

 appear more distinctly if repeated thus algebraically : — 



Let the effects of a luminous hot body on the black and white 

 thermometers respectively be, 



without a screen h w 



with a glass screen .... 6^ w^y 

 Now, by observation, we know the ratios in these two cases, and we 



