Scientific Intelligence. — Mechanical Philosophy. 391 



not even excepting sinking, which effectually destroys the white ant. 

 — Idem. 



4. Electricity of the Solar Rays. (Letter from Sig. Carlo Mat- 

 trucci, of Forli, to Professor Gazzeri.) — " I hasten, Sir, to commu- 

 nicate to you some experiments which appear to me to deserve the 

 attention of philosophers. Having been for a long time persuaded of 

 the existence of electricity in the solar rays, I wished to ascertain the 

 fact by experiments. Having for the purpose exposed to the sun a 

 delicate condensing electrometer of gold leaf, I soon perceived the 

 leaves diverge and open themselves also on that side of the glass 

 case which was directly exposed to the solar action, as if they had 

 been attracted by it. Being induced from this first fact to suspect 

 glass in this situation electrified, I was anxious to know if this were 

 the case : wherefore, having left some plates of it in the sun, in a few 

 moments I touched them in different places with the ball electrome- 

 ter, when a very perceptible divergence ensued, which, however, was 

 much more apparent when I touched the plates, although lightly, with 

 a flat surface, since the effects of the friction and the pressure did not 

 afford a doubtful result. I concluded, then, that the solar rays had 

 the power of electrifying glass, and it only remained for me to ascer- 

 tain if this effect were owing to the real existence of electricity in 

 these rays, or rather to the increased temperature of the glass, which 

 I could easily determine by heating a plate of glass, and trying it with 

 the electrometer. This I did several times, but never discovered 

 any signs of electricity. I observed, also, that the glass plate ex- 

 posed to the rays of the sun, never became electric if placed beneath 

 another glass plate, or if the face of the sun was obscured by the in- 

 tervention of a cloud. These few experiments which I have been 

 induced to perform, seem to me sufficient to prove the existence of 

 electricity in the solar rays. The influence of such a fact on the 

 meteorological phenomena of nature, will, I hope, induce yourself 

 and other philosophers to pursue the subject farther." (Antologia,, 

 No. 100. Forli April 25, 1829.)— Idefn. 



Professor Saverio Barlocci, of Rome, in a Memoir on the influ- 

 ence of Solar Light, in the Production of Electric and Magnetic Phe- 

 nomena, inserted in Vol. XLL of the Giornale Arcadico, relates the 

 following experiments which he had- performed, to ascertain the elec- 

 tric power of the solar light. Having decomposed it with a prism, he 

 made the red ray and the violet ray fall upon two discs of blackened 



