Researches into the Physiology of the Human Voice. 269 



Teriodide of Gold 'with Iodides of Sodium and Ammoiiitan. — 

 These salts are prepared by digesting solutions of the respec- 

 tive iodides on the teriodide. They both crystallize in black 

 four-sided prisms, having much lustre, those containing am- 

 monia being generally flattened. They are both deliquescent, 

 that of sodium so much so that it is obtained in crystals with 

 great difficulty; that of ammonia only in a moist atmosphere. 

 I have not ascertained whether or not they contain any water 

 of crystallization. 



The teriodide dissolves also in solutions of the iodides of 

 barium and strontium, giving similar dark-coloured solutions. 

 A solution of the iodide of iron likewise takes it up in consi- 

 derable quantity, and forms with it a crystallizable compound. 



The solution in hydriodic acid has the same dark red co- 

 lour. Set aside to spontaneous evaporation, it deposits mi- 

 nute black prisms, which, on exposure to the air, acquire a 

 beautiful purple tint, probably from loss of iodine. Whether 

 these are merely crystals of the teriodide, or a compound with 

 hydriodic acid, I have not ascertained. The former is the 

 more probable. 



Like the solutions of the terchloride, those containing the 

 teriodide are also decomposed by the addition of caustic am- 

 monia. The precipitate is of a brown colour, more or less 

 dark, sometimes almost black, and, like fulminating gold, it 

 detonates when heated, giving off iodine and ammonia. The 

 dark precipitates are obtained by pouring liquid ammonia into 

 an excess of the teriodide ; the lighter, by dropping a solution 

 of the teriodide into caustic ammonia, and agitating at each 

 successive addition. They are decomposed by hot nitric acid, 

 evolving iodine, and leaving a mixture of proto-iodide and me- 

 tallic gold. 



Durham, August 30, 1836. 



LVI. Experimental Researches into the Physiology of the Hu- 

 man Voice. By John Bishop, Esq., 8^c. ^c. 

 [Continued from p. 209.] 



T^HE lungs having been supplied with air by the muscles of 

 -^ inspiration, the ligaments of the glottis are drawn into 

 the vibrating position. 



The air in the chest and trachea being now condensed by 

 the muscles of expiration, a portion of the glottis yields to its 

 pressure, and the edges are curved upwards so as to be nearly 

 parallel to the axis of the vocal tube, leaving between them an 

 aperture through which the air passes. The tension and elas- 

 ticity of the vocal ligaments tend to restore them to the plane 



