26 On the Restoration of Sight, 



up in the middle of the tube. By the continued action of 

 heat, the summit of the rod (at a) had been rounded in fu- 

 sion, and the mass being now softened had sunk by its 

 weight, and spread below, so as to mould itself in the tube, 

 and fill its lower part completely (dfge). At the same time, 

 the viscid fluid adhering to the sides (at e and d), while the 

 middle part was sinking, had been in part left behind, and in 

 part drawn out into a thin but tapering shape, united by a 

 curved surface (at I and c) to the middle rod. When the 

 platina tube was unwrapt, the thin edges (at e and d) were 

 preserved all round, and in a state of beautiful semi-trans- 

 parency. (I have attempted to represent the entire specimen, 

 as it stood on its cone of W3X, in fig. 34.) The carbonate, 

 where moulded on the platina, had a clean pearly whiteness, 

 with a saline appearance externally, and in the sun shone 

 with facettes. Its surface was interrupted by a few scat- 

 tered air-bubbles, which had lain against the tube. The 

 intervening substance was unusually compact and hard under 

 the knife. The whole surface {ehacd, fig. 31.), and the 

 inside of the air-bubbles, had a vitreous lustre. Thus, every 

 thing denoted a state of viscid fluidity, like that of honey. 



These last experiments seem to obviate every doubt that 

 remained with respect to the fusibility of the purest car- 

 bonate, without the assistance of any foreign substance, 



[To be continued.] 



IV. Upon the Restoration of Sight, ivhich takes place in 

 Mankind and some Animals, without the Assistance of 

 Art. By ill. Portal*. 



Oight may be extinguished by various causes, and is re- 

 stored when these causes are removed ; several of them are 

 well known : the absence of the aqueous humour, various 

 overflowings in the anterior and posterior chambers of the 

 eye, indurations of the vitreous humour, paralysis of the 

 optic nerve, some alteration of the crystalline humour, &c. 

 But history has preserved examples of all these blindnesses 



* From Annates du Museum d'Histoire Naturclh, vol. vj. 



having 



