Flotation of Minerals. 563 



float, or a very poor float: — Muscovite, ainorphous niahichite, 

 Turquoise, gvpsiiui, quartz and particles of slate. Calcite and 

 niuscovite if crushed together can be separated by oleic acid, 

 the calcite floating, and the niuscovite not absorbing the oil. 

 Copper matte will give a flotation with oleic acid in HoSO^ 

 solution. Whether a mineral is caused to float, or is merely 

 i-ollected together in a mass or in small rounded balls, or is 

 made granular but coherent, is dependent on the quantity of oil 

 used. A series of tests carried out showed that with an excess 

 ■of oil over the mineral the latter was caused to float by being 

 carried to the surface of the water by the lighter oil. With oil 

 jind the mineral in certain ratios as 5 gms. oil to 20 or 30 gms. 

 ■of zinc blende the oil and mineral formed one globular coherent 

 mass. By increasing the amount of mineral and keeping the 

 same amount of oil, smaller rounded masses of oil and mineral 

 formed which would not float until finally with a large amount 

 of mineral (150 gnis.) and 5 gms. oil a granular product was 

 formed which would float on violent agitation, being buoyed up 

 by attached air bubbles. On adding acid to the minerals which 

 have absorbed oils in presence of water, most minerals other 

 than sulphides and metals will not float on heating, the acid 

 apparently causing them to separate from the oil. The amount 

 of acid required to make the action selective is very small, but 

 from the i-esults of numerous tests it is apparent that with 

 only minute quantites of acid the action is only partially selec- 

 tive. If more acid is used the freer from gangue the concentrates 

 will be. Calcite and oleic acid will not mix in the presence of 

 oxalic acid, although the calcite is not apparently attacked. 

 Calcite will absorb oleic acid in the presence of acetic and lactic 

 acids. There is no very marked difference between the be- 

 haviour of sulphur and oleic acid in an acid solution or in 

 water. Carbon bisulphide acts similarly to an oil, and is ap- 

 parently absorbed by the minerals. 



Oiled Minerals under rediiced pressure. 



Crystalline fragments of tourmaline, garnet, zinc blende, 

 ■galena, pyrite, quartz, gypsum, andalusite and calcite — were 

 taken, two of each, one oiled with oleic acid and the other 



