Flotation of Minerals, Part II. 309 



With 80 gms. galena a slight excess of oleic acid still showed 

 on the surface of the water. All the oily products under the 

 surface of the water were feebly coherent, but no distinct putty 

 stage occurred. With 200 gms. galena a few air bubbles became 

 attached. 



Using galena crushed to pass an 80-mesh, and retained on a 

 120-tnesh sieve, with 5 gms. oleic acid, all the oil was carried 

 down with 60 gms. of the mineral to form the characteristio 

 putty-like magma. A very small excess of oil showed on the 

 surface of the water with 40 gms. of galena. 



With galena crushed to pass r20-mesh sieve all the oil was 

 carried down by 40 gms. of the mineral. When 30 gms. had 

 been added, the plastic putty-like mass was formed. With 120 

 gms. of this sized galena to 5 gms. of the oleic acid, the product 

 of the galena and oil was much less coherent than with 120 gms, 

 of the galena crushed to pass an 80 and remaining on a 120- 

 mesh sieve. 



In water witlioiit tlie addition of acid. 



The foregoing tests were carried out with water acidulated 

 with 0,5 gm. sulphuric acid. The following is a short summary 

 of the results of tests on the same lines, but using water which 

 had not been acidulated. 



Using galena crushed to pass r20-mesh sieve and 5 gms, of 

 waste engine oil (fairly thick), the same general results were 

 obtained as when acid was present. All the oil was carried 

 down w4th 30 gms. of the galena. The putty-like magma 

 occurred when 40 gms. had been added, this product being- 

 firmer than that formed with 30 gms. 



When 60 gms. of galena had been added the magma broke 

 up into granules. With 80 gms. of galena, air bubbles showed 

 a tendencv to become attached, and with 120 gms. galena a 

 marked tendency to float on agitation was observed. 



Other tests on the same lines without acid showed that with 

 smaller proportions of oil to mineral the product was more 

 prone to attach air bubbles and had a more fiocculent appear- 

 ance than when acid was present. 



Two bottles containing 50 gms. galena and 0,8 gm. oleic acid 

 with 200 c.c. water were taken, and to one of them 0.5 gm. 



