The final results are shown by the figures in full-faced type in the last and third from the last columns. By plotting these figures we find that 10 per cent of the stones are less than 35 millimeters in diameter, and 60 per cent are less than 51 millimeters. The “uniformity coefficient,” as described below, is the ratios of these numbers, or 1.46, while the “effective size” is 35 millimeters.

II. ANALYSIS OF A SAND BY MEANS OF SIEVES.

A portion of the sample was dried in a porcelain dish in an air-bath. Weight dry, 110.9 grams. It was put into a series of sieves in a mechanical shaker, and given one hundred turns (equal to about seven hundred single shakes). The sieves were then taken apart, and the portion passing the finest sieve weighed. After noting the weight, the sand remaining on the finest sieve, but passing all the coarser sieves, was added to the first and again weighed, this process being repeated until all the sample was upon the scale, weighing 110.7 grams, showing a loss by handling of only 0.2 gram. The figures were as follows:

Sieve
Marked.		Size of
Separation
of this
Sieve.
Millimeters.		Quantity
of Sand
Passing.
Grams.		Per Cent
of
Total
Weight.
190.105.5 .5
140.1351.3 1.2
100.1824.1 3.7
60.32023.2 21.0
40.46 56.7 51.2
20.93 89.1 80.5
102.04 104.6 94.3
63.90 110.7100.0

Plotting the figures in heavy-faced type, we find from the curve that 10 and 60 per cent respectively are finer than .25 and .62 millimeter, and we have for effective size, as described above, .25, and for uniformity coefficient 2.5.

III. ANALYSIS OF A FINE MATERIAL WITH ELUTRIATION.

The entire sample, 74 grams, was taken for analysis. The sieves used were not the same as those in the previous analysis, and instead of mixing the various portions on the scale they were separately weighed. The siftings were as follows:

Remaining on sieve marked 10, above 2.2 millimeters 1.5 grams
Remaining on sieve marked 20, above .98 millimeters 7.0 grams
Remaining on sieve marked 40, above .46 millimeters 22.0 grams
Remaining on sieve marked 70, above .24 millimeters 20.2 grams
Remaining on sieve marked 140, above .13 millimeters 9.2 grams
Passing sieve140, below .13 millimeters 14.1 grams

The 14.1 grams passing the 140 sieve were thoroughly mixed, and one third, 4.7 grams, taken for analysis. After ignition just below a red heat in a radiator, the weight was diminished by 0.47 gram. The portion above .08 millimeter and between .04 and .08 millimeter, separated as described above, weighed respectively 1.27 and 1.71 grams, and the portion below .04 millimeter was estimated by difference [4.7 - (0.47 + 1.27 + 1.71)] to be 1.25 grams. Multiplying these quantities by 3, we obtain the corresponding quantities for the entire sample, and the calculation of quantities finer than the various sizes can be made as follows:

Size of Grain.Weight.
Grams.		Size of
Largest
Particles.
Millimeters.		Weight of all
the Finer
Particles.
Grams.		Per Cent by
Weight of
all Finer
Particles.
Above 2.20 millimeters 1.50....74.00100
.98-2.20 millimeters 7.002.2072.50 98
.46- .98 millimeters22.00 .9865.50 89
.24- .46 millimeters20.20 .4643.50 60
.13- .24 millimeters 9.20 .2423.30 32
.08- .13 millimeters 3.81 .1314.10 19
.04- .08 millimeters 5.13 .0810.29 14
.01- .04 millimeters 3.75 .04 5.16 7
Loss on ignition (assumed to be less than .01 millimeter) 1.41 .01 1.41 1.9