76 



MARINE BOTTOM SAMPLES OF LAST CRUISE OF CARNEGIE 



Table 25. Multiple analyses by the pipette method of fractions less than 70 microns in particle diameter 



(Data reduced to standard size grades) 



Total 



100.0 



100.1 



Settling in dark "constant-temperature" room was continued for about 95 hours. Ten and six samples 

 were taken from A and B respectively, at irregular intervals and at depths below surface of suspension be- 

 tween 10 and 3 cm (for settling velocities see fig. 11). Temperatures varied between 14.°5 and 12.°3 C, but 

 rate of change of temperature was less than 0.°04 per hour. 



Average deviation of percentages in each size grade = 1.3 per cent; <r = standard deviation of percent- 

 ages in each size grade = 1.2 per cent; P.E. = probable error of percentages in each size grade = 0.8 per 

 cent. Without first value, average deviation = 1.0 per cent; a = 0.9 per cent; P.E. = 0.6 per cent. Aver- 

 age deviation of cumulative percentages = 1.4 per cent; tr = 1.4 per cent; P.E. = 0.9 per cent. Without 

 first value, average deviation = 1.1 per cent; a = 1.0 per cent; P.E. = 0.7 per cent. 



Sample 19. Triplicate analyses on parts dispersed separately 



70 

 31.3 

 15.6 

 7.81 

 3.91 

 1.95 

 0.98 

 0.49 



Total 



100.0 100.0 100.0 



100.0 



For A and B, settling in dark "constant-temperature" room, at temperatures between 17.°6 and 16.°6 C 

 was continued for about 45 hours; for C, settling was continued for 73 hours at temperatures between 13.°4 

 and 12.°4 C. In all three experiments 8 samples were taken at irregular intervals, and at depths below sur- 

 face of suspension between 10 and 4 cm. Settling velocities are shown in fig. 11. 



