PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 645 



canal — numerous experiments have been tried with steam, none of 

 which can be regarded as entirely successful. 



On the river Oise, in France, boats have lately been drawn by 

 means of a steam-carriage on the towing-path, which readily movea 

 up the steep grade at each lock. 



Indium. 



This rare metal was first discovered about three years ago by 

 Messrs Ricbter and Rich, of the Erieburg Mining Academy, in 

 the zinc bl'ende, in the vicinity of Frieburg. It has lately been 

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

 near Schlagenw. M. Winckler considers it best, in extracting indium, 

 to treat the roasted blende by hydrochloric acid, to precipitate by an 

 excess of zinc the indium, copper, lead, cadnium, &c., and to sepa- 

 rate these metals by sulphuretted hydrogen and carbonate of baryta. 

 M. Schrotter modifies the method by treating the blende, after 

 roasting, with sulphuric instead of hydrochloric acid, precipitating 

 the indium by zinc and fractioning the precipitates ; the purifica- 

 tion of indium is then easier in consequence of this division. In- 

 dium may be ranked among the heavier metals ; its specific gravity 

 being from 7. 11 in the granular state to 7.28 after hammering. Its 

 color resembles that of platinum. Its luster is not tarnished by 

 exposure to air or even 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 colorless, but when exposed to 

 the flame of a Bunsen burner, impart to it a blue or violet tinge. 

 In its electric properties indium resembles cadmitim, but is more 

 electro-negative. 



Food Requiked for Internal WoEii;. 

 Professor Frankland publishes the following statement, which 

 contains the weight of various articles of food required to sustain 

 respiration and circulation in the body of an average man during 

 twenty-four hours : 



Name of Food. ^ Weight in oz. 



Cod liver oil ._ 1.5 



Butter.. 1.8 



Cocoa-nibs 1.9 



Cheshire cheese _. _ 3.0 



Oatmeal __. 3.4 



Arrowroot ._ 3.4 



Flour.. _ 3.5 



Pea-meal „ , 3.5 



Gelatine 3.6 



