Scientific Congress at Florence. 69 



PROCEEDINGS OF THE SECTION OF PHYSICS, ETC., OF THE SCI- 

 ENTIFIC CONGRESS HELD AT FLORENCE IN SEPTEMBER 1841*. 



We owe to the kindness of M. Matteucci an extract from the 

 minutes of the meetings of the physical, mathematical and chemical 

 sections, of which he is the Secretary. 



M. Pacinotti read a memoir on the induced currents which are 

 developed in magnets put in rotation. After having studied the 

 principal circumstances of this phsenomenon, he showed how it may 

 be made use of in order to study the distribution of magnetism in a 

 magnet, and in order to have a current of constant power ; and how 

 also suitably, in bringing together several magnets in rotation, we 

 may have a very powerful electrometer. 



M. Cagnozzi read a memoir on tonography. He presented an in- 

 strument which he calls a tonographe, and with which he proposes 

 to write down the music of declamation. 



M. Vegui showed some wire ropes (cordes en fil de fer), in the 

 centre of which there is a cord of hemp : it appears that this modi- 

 fication destroys the rigidity of ordinary wire ropes. 



Professor Cassiani of Parma read a memoir, the object of which is 

 the studjr of the oscillatory motion observed long since in an astatic 

 system of magnetic needles. He finds that this motion is connected 

 with the electric state of the atmosphere. 



Prince Louis Bonaparte exhibited some platina gilt by De la 

 Rive's process, and observes that this metal takes the gilding better 

 than silver. He explains this, on the one hand, by the greater 

 density of the platina, and, on the other, by the insoluble layer of 

 chloride of silver, which must withstand the perfect gilding of silver. 



M. Matteucci spoke of the experiments lately made in England, 

 and of those of M. Peltier in France, according to which the vapour 

 of water appears to him to manifest a state of electricity when it is 

 formed at a high degree of tension and at very elevated tempera- 

 tures. He afterwards noticed the observations which he has made 

 for the purpose of studying the electric state of the atmosphere near 

 the columns of vapour which rise in the Lagoons of Tuscany, where 

 boracic acid is produced. He says that he has not observed any 

 diflference, with respect to electricity, between the air near the La- 

 goons and that at a great distance from them. From this he con- 

 cludes, that we cannot consider the slow evaporation of water from 

 salts, or from the sea, as the cause of atmospheric electricity. 



M. Vincent Amici extends the principle of virtual velocities, and 

 of living forces, to liquids which are acted upon by any forces what- 

 ever in their elements, and compressed at their surface. 



M. Majocchi communicated a series of experiments, the result of 

 which is that heat, whether conducted or radiating, is endowed with 

 the same property which M. Becquerel, jun., found existing in those 

 rays of the spectrum which he has named continuateurs . It is thus 

 that he has discovered that photogenic papers submitted to the ac- 

 tion of light during an exceedingly short time, and without their 



* From the Bidliolhc(juc Univcrsdlc, No. 69, October 1841, p. 205. 



