181 



mistaken for pyrites. Upon subjecting them, however, to more rigid 

 examination than they had previously received, Dr. Wollaston ascer- 

 tained them to be titanium in its metallic state. He found them not 

 only harder than pyrites, but so hard as to scratch glass, and even 

 agate. They are neither acted upon by nitric, sulphuric, nor muri- 

 atic acids ; nor are they dissolved by nitro-muriatic acid . They are 

 inrusible before the blowpipe, but become superficially oxidized, and 

 borax restores the cleanliness of their surface, by dissolving the oxide. 

 By nitre they are rapidly oxidized ; and by combining its action with 

 that of borax, they may be entirely dissolved. The fused mass is so- 

 luble in muriatic acid ; and from this solution the alkalies precipitate 

 a white oxide, insoluble in pure and carbonated alkalies. When 

 evaporated, the excess of muriatic acid may be driven off, and a so- 

 luble muriate remains, in a state favourable for exhibiting the leading 

 properties of titanium. Infusion of galls produces in this solution the 

 characteristic red precipitate ; prussiate of potash occasions one of 

 similar colour, which differs from prussiate of copper by inclining to 

 orange instead of purple, while prussiate of uranium is rather brown 

 than red. 



Although the crystals are imbedded in sulphuret of iron, Dr. Wol- 

 laston found in them neither iron nor sulphur. That they are in the 

 metallic state, is proved by the perfection with which they conduct 

 a feeble degree of electricity. They did not unite with tin, lead* 

 silver, or copper. From their extreme infusibility, Dr. Wollaston 

 thinks that they have not been formed by crystallization in cooling 

 from a state of fusion, but have received their successive increments 

 by reduction of the oxide dissolved in the slag around them, a mode 

 of formation to which we must have recourse for conceiving rightly 

 the formation in nature of many other metallic crystals. 



On the Difference of Structure between the Human Membrana Tym- 

 pani and that of the Elephant. By Sir Everard Home, Bart. V.P.R.S. 

 Read December 12, 1822. [Phil. Trans. 1823, p. 23.] 



In an elephant three weeks old, the membrana tympani was of an 

 oval form, l inch long, and 1 broad. The muscular fibres lie upon 

 its inner surface, and terminate by an attachment to the point and 

 two sides of the malleus, so that one portion of the fibres is short, 

 and the other more than double their length. From this structure 

 the elephant cannot adapt its ear to musical sounds in the same 

 manner the human ear does ; but in Sir Everard's opinion, it is 

 enabled by the long fibres to hear sounds at a great distance. In 

 regard to musical sounds, high notes scarcely excite its attention, 

 but it listens to the lower ones with apparent satisfaction. In neat 

 cattle, and in the deer, the membrana tympani is oval, and the struc- 

 ture approximates to that in the elephant. In the horse, the hare, 

 and the cat, the handle of the malleus lies in the middle line, so that 

 the fibres on the two sides are equal, and the organ appears simi- 

 larly constructed in the whole of the feline tribe. 



