PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 605 



bone, a movable fulcrum with Avhieli both organs arQ connected by 

 muscle and ligament. The connection is such that a movement of 

 the tongue will require a readjustment of the muscles of the 

 larynx, to keep the latter organ in the same place and condition 

 as before, and so observe the same pitch. Hence, through the 

 two, successive vowels can be uttered on the same pitch, and it is 

 much more easy and natural to vary the pitch. Second: Every 

 singer knows that only with certain vowels can the extremely 

 high notes be fairly reached, and only with certain others, again 

 the lowest. The connection" just mentioned between the tongue 

 and the larynx will suffice to explain this also, though we would 

 not affirm that there is no other cause concurrent therewith. 

 Third: The vowels cannot be uttered on every pitch with equal 

 purity of tone, and there would seem to be one certain key for. 

 each, on which the purest tone is heard— the purest musically, we 

 mean, that is, the most free from discordant intermixture. The 

 same cause above mentioned may have an agency in this case also, 

 but the author thinks that here the eifect may be due primarily to 

 the form and dimensions of the vowel-tube. 



Indium. 



This rare metal was first discovered about three years ago by 

 Messrs. Richter and Eeich of the Frieburg Mining Academy, iu 

 the zinc blende, in the vicinity of Frieburg. It has lately been- 

 found by M. M. Kachler and Schrotter, in the blende at Schon- 

 feld, near Schlagenw. M. Winckler considers it best, in extract- 

 ing indium, to treat the roasted blende by hydrochloric acid, to 

 precipitate by an excess of zinc the indium, copper, lead, caduium, 

 &c., and to seperate these metals by sulphureted hydrogen and 

 carbonate of baryta. M. Schrotter modifies the method by treat- 

 ing the blende, after roasting, with sulphuric instead of hydro- 

 chloric acid, precipitating the indium by zinc and fractioning the 

 precipitates; the. purification of indium is then easier in conse- 

 quence of this division. Indium maybe ranked among the heavier 

 metals; its specific gravity being from 7.11 in the granular state, 

 to 7,28 after hammering. Itscolor resembles that of platinum. It« 

 luster IS not tarnished by exposure to air or even to boiling water. 

 It is softer and more malleable than lead, and is as volatile as 

 magnesium or zinc. It forms but one oxide. Its salts are color- 

 less, but when exposed to the flame of a Bunsen burner, impart to 

 it a blue or violet tinge. In its electric properties indium resembles 

 caduium, but is more electro-negative. 



