562 Kenneth A. MlcJde: 



company's process contained Si02 (0.112 gms. per 100 c.c), Fe, 

 Al, Zn, Mn, and Ca. A sample of the Central Mine'^s concen- 

 trates (oil and acid process) was washed with strong 

 NaOH, and then washed till free from NaOH. The zinc blende 

 would not then float on top of air-free water on boiling-, but on 

 making acid with H.:,SO, a float was obtained. No float could 

 be obtained by adding ammoniiun carbonate. Another sample 

 of the Proprietary's zinc concentrates washed free from acid, and 

 then washed with strong NaOH, and then washed free from 

 alkali would not float on heating in tap or air free water, but 

 floated on adding acetic or sulphuric acid. 



Behaviour of Minerals and Metals with Oils, Etc. 



On the surface. — None of the minerals tried would float on 

 the surface of oleic acid (commercial), kerosene, or alcohol. 

 Copper foil floated on oleic acid, but not so persistently on kero- 

 sene. Iron wire would not float on kerosene or oleic acid, but 

 showed a tendency to float, not sinking immediately. Zinc 

 blende, galena and the other minerals would not float on alcohol 

 but did not immediately sink. 



Oti heating. — None of the minerals floated on heating in 

 kerosene or oleic acid. 



Under reduced pressure. — None of the minerals or metals 

 floated when immersed in oleic acid, alcohol, or kerosene under 

 reduced pressure. 



Behaviour of Oiled Minerals in Water and 

 Acid Solutions. 



Nearly all the minerals and metals will absorb oil if shaken 

 up in water to which oil has been added. If previously oiled 

 as with oleic acid, vaseline, or kerosene, nearly all minerals will 

 float in water. Some float in the cold,; others require heating 

 or reduced pressure. The following float well : — Calcite, 

 sulphur, galena, garnet, zinc blende, wolfram, cassiterite, siderite, 

 cerussite, magnesite, azurite, malachite, rhodonite, and some 

 quartz, and the metals in form of foil. The following give no 



