320 The American Geologist. November, i903 
of their particles, other things being- equal. The fact that the 
water-transported clays or kaolins are more plastic than the 
residual is regarded as due to the abrasion the}^ have suffered 
during the process of transportation. As bearing upon the 
effect of the shape of the particles upon plasticity, he instances 
the fact that clays kneaded in a "Schlcpp" mill, where the 
motion is a crushing and dragging one and such as to give 
rise to flattened particles, are more plastic than those kneaded, 
for the same length of time, in "Trommel" mills, where the 
resultant particles are angular and of irre;'gular form. This, 
too, he thinks will explain the fact that an unplastic clay can- 
not be rendered plastic through artificial grinding, whereby 
the kaolin particles become broken into angular bits, which 
never have the same degree of plasticity as the naturally 
rounded and waterworn particles. (Is not this a trifle con- 
tradictory?) 
The tendency shown by the finely ground kaolins to crack 
in the process of baking, he seems to regard as due to the ex- 
plosive action of the steam generated b}^ the heat, the; com- 
pactness of the clay rendering its gradual escape impossible. 
He notes that the plagioclase feldspar undergoes kaoliniza- 
tion much more readily than does orthoclase, and that the 
latter is itself more readily attacked than microcline. 
The transformation of the three most important feldspars 
into kaolin he shows as follows : 
SiOa AI2O3 K2O H2O % 
1. Orthoclase 64.86 18.29 16.85 100.00 
Lost 4324 16.85 60.09 
Taken up 6.45 6.45 
Kaolinite 21.62 18.29 6.45 46.36 
SiOo AI0O3 NasO H2O % 
2. Albite 68.81 iq.40 11-79 100.00 
Lost 45.87 11-79 57-66 
Taken up 6.85 6.85 
Kaolinite 22.94 19. 40 6.85 49.19 
SiOz AI2O3 CaO H2O % 
3. Anorhite 43-3° 36-63 20.07 100.00 
Lost 20.07 20.07 
Taken up 12.92 12.92 
Kaolinite 43-3i'» 3663 12.92 92. 85 
