On the Multiple Sounds produced by Vibrating Bodies. 27 



faces in the two minerals differ. The specific gravity of the 

 two minerals is — 



Brookite. Arkansite. 

 4-125 to 4*169 Breithaupt. 3'854 Shephard. 



3-810 Hermann. 3-952 Breithaupt. 



4-128\transparentn 3*892^ 



4-131 J crystals. [tt t> 3-923 > Rumnielsberg. 



4-165 1 opake ^"- ^ose. g.g^^^J 



4-167/ crystals. J 

 4-156 Rammelsberg. 



Further, the specific gravity of Arkansite is almost identical 

 with that of Anatase ; it may therefore be said that Arkansite 

 is native titanic acid with the form of Brookite and the density 

 of Anatase. 



SMECTITE. BY L. A. JORDAN. 



[PoggendorfF's Annalen, vol. Ixxvii. p. 592,] 



This mineral, which occurs at Cilly in Lower Styria, and is 



likewise found at Zeny in Croatia, has been analysed by L. 



A Jordan, who has found for it a composition corresponding 



to' the formula p^'^l 3Si03 + ^^S^|si03 + i2HO, viz. 

 Silica 51-21 



Alumina . . 

 Peroxide of iron 

 Magnesia . . 

 Lime .... 

 Water . . . 



12-25 

 2-07 

 4-89 

 2-13 



27-89 



[To be continued.] 



VL On the Multiple Sounds and Optical Phcenomena pro- 

 duced by Vibrating Bodies. Theorij of the Boixi. By M. 

 J. Antoine*. 



MDUHAMEL has just published a novel and inge- 

 • nious theory on the multiple sounds of sonorous 

 bodies f. I know not what reasons have led him to imagine 

 that justice has not been done him. On this point the learned 

 academician is under an illusion. Physicists will render him 

 justice, in spite of the disdain which M. Duhamel aifects, 

 when he supposes them as httle advanced as at the period 

 of Father Mersennus, and in spite of their well-founded belief 



* From the Annates de Chimie et de Physique for October 1849. 

 t See Phil. Mag., vol, xxxtv. p. 416. jc^a^i^'m iw^J lu 



