[burton & currie] coagulation OF ELECTROLYTES 



111 



In the accompanying table are given the details of the various samples ; 

 in the last column is given the amount of solid coagulum deposited 

 from each sample. 



The supernatant liquid was quite clear in the case of the last 

 sample and almost clear in the case of number 6. These results are 

 illustrated in the figure from which it is seen that there is a very 

 definite indication of the amount of aluminium necessary to produce 

 coagulation. 



These results are paralleled exactly by the behaviour of the 

 second set of 25 c.c. samples which were left merely to the effect of 

 gravitation. After the end of weeks the samples corresponding 

 to numbers 5, 6 and 7 were completely coagulated, while the other 

 samples showed decreasing degrees of sedimentation corresponding 

 to the amount of aluminium sulphate added. 



Determination of the Density of the Arsenious Sulphide Colloidal 



Particles 



In order to make a calculation of the force acting upon the 

 colloidal particles the density of the arsenious sulphide in the colloidal 

 state was determined. The ordinary specific gravity bottle method 

 was used and the temperature of all the samples was 23°C. 

 z; = volume of bottle = 50. 2024 ces. 



Wi = weight of AS2S3 in bottle full of solution = 0. 1176 grms. 



102 = weight of bottle full of colloidal solution = 50.4766 grms. 



W4= weight of liquid medium in bottle full of solution 50.3590 

 grms. 



J = density of liquid medium of solution = 1.0038, as found by 

 experiment. 



• • — = volume of liquid medium in bottle full of solution = 



