272 The American Geologist. November, i898 
1. A weighed amount of clay, dried at 100° C, and pre- 
viously ground to pass through a 100 mesh sieve, was placed 
in a brick-shaped tin vessel, the bottom of which was finely 
perforated and lined with filter paper, to prevent the escape 
of clay. This vessel was then supported in a small tank sup- 
plied with water, just high enough to reach the perforated 
bottom. 
Immediately following the contact of water with the clay, 
a marked down-pull of the latter occurred, effecting the pri- 
iiiary sJirinkagc of the incoherent mass. 
2. The next experiment was the 'determination of the re- 
lative rate of loss of water on drying at ioo°C., by weighing at 
fixed intervals; and (3) of the amount of shrinkage for each 
dimension, by careful measurement at the successive stages 
of drying. The shrinkage here involved is that referred to as 
secondary. 
(4) Other experiments with specially devised apparatus 
tested the tenacity of the clays at intervals during drying, be- 
ginning with the saturated condition, and ending with the dry 
brick, thus determining the degree of consolidation. 
These experiments naturally showed results widely vary- 
ing among the diflferent clays. A brief summary of the more 
important of them follows. 
I. The clays absorbed water in amounts varying, re- 
spectively, from 40 to over 200 per cent, by weight. 
II. Generally speaking, those, which were originally in- 
coherent in nature, absorbed the largest amounts. 
III. The rate of drying varied directly with the amount 
of water absorbed. 
IV. The amount of sJirinkage varied according to a com- 
plex of conditions, such as density, the size and shape of par- 
ticles of the clay-base, and their state of aggregation, also 
upon amount of sand present, and the size and shape of its par- 
ticles. 
*The anomalous fact was discovered, that, among clays otherwise 
similar, those containing the greatest amount of sand, in cases as 
high as 40 per cent., shrank the most. This is noteworthy in view of 
the fact that sand is often added by potters and brick-makers, to 
diminish the shrinkage of a clay. For the case in hand, however, an 
explanation may be found in the fact, that the greater part of this 
sand is in extremely minute particles, probably smaller than those 
of the clay. 
