946 
zation to obtain subjects for their pupils; and 
consequently the neglect of the mollusca con- 
tinues. 
The work of Lang might have advanta- 
geously been supplemented by a chapter calling 
attention to the gaps in our knowledge and em- 
phasizing the need of research and the rewards 
which will undoubtedly fall to the lot of him 
who decides to investigate patiently in a field 
where not one in a thousand species is anatom- 
ically known, and where a careful embryological 
study, as of the development of the gills in 
Pelecypods, will produce the most far-reaching 
results, if carried out with thoroughness. 
When this student appears, he will find in the 
work of Lang a storehouse of facts and a record 
of hypotheses which cannot fail to be of the 
greatest service in his studies. 
W. H. DALL. 
Clays of New York, their Properties and Uses. 
By HetnricH Ries. Bulletin of the N. Y. 
State Museum, No. 35. Vol. 7. 1900. Pp. 
450. Plates, 140. 
Somewhat over ten years ago, the author of 
the work before us took up the study of the 
clays of the Hudson River region and the 
industries based upon them. The venture had 
all the charm of novelty, because up to that 
time it had not occurred to anyone to in- 
vestigate these humble resources, which had 
apparently impressed all observers as possess- 
ing little of interest or of importance. And yet 
the investigation proved that the clays of the 
state were the raw material of the most im- 
portant of all its mineral industries, and they 
had evidently been passed by, because of their 
ordinary and simple nature, because they did not 
appeal to the imagination. The experience 
is not unique, as will be seen from the follow- 
ing incident. While the writer was recently 
discussing the subject with a Russian friend, 
the latter remarked that he had discovered on 
the steppes, extensive deposits of china-clay, 
which, when worked up and sold, would bring 
$150.00 per ton. He had great difficulty in 
arousing interest, and yet had he found in any 
such quantity, gold ore worth $5.00 or $10.00 
per ton the greatest excitement would have 
immediately broken out. 
SCIENCE. 
(N.S. Von. XIII. No. 337. 
Ten years ago in America, scientific interest 
in clays was chiefly limited to those which 
supplied refractory materials. Our literature 
was small. The New Jersey Geological Sur- 
vey prepared a valuable report in 1878, and 
in the later eighties the Geological Survey 
of Ohio published an important contribution, 
both reports being issued by States where the 
fire-brick industry was and is important, but 
except for these two contributions almost no 
attention had been elsewhere paid to clays by 
official scientific bodies. Conditions have greatly 
changed since then; the vitrified brick industry 
has sprung up ; shales, once the most despised 
and neglected of rocks, are now utilized in enor- 
mous quantity; clays are purified and washed, 
and the ceramic arts have made great strides. 
It is but just to Dr. Ries to say that his writings 
have contributed in no small degree to the re- 
sult and have brought within the reach of 
workers and readers alike, the possibilities of 
this invaluable raw material. 
The present work is his most extensive con- 
tribution. To estimate it properly, it must be 
appreciated that it is intended as much for the 
practical workers as for the libraries and lab- 
oratories of institutions of learning. The bal- 
ancing of theoretical investigations with de- 
scriptive matter has therefore been necessarily 
considered with care by the author, but it has 
been performed with discretion and in a way 
to attain the most useful result. The scientific 
reader, however, will be glad to know that 
all the author’s results in the investigation of 
the physical properties of clays have not yet 
been published and that further contributions 
may be expected. 
The work opens with the generalities of 
clays; their origin; mineralogy ; properties ; 
analysis; classification; geologic distribution 
in New York and in the United States. 
The methods of digging clay and the geologic 
features of the deposits are then described, 
after which the brickmaking industry receives 
detailed description. This is followed by terra 
cotta, roofing tile, sewer pipe, hollow brick, 
etc.; floor tile, decorative tile, fire clays and 
pottery ; each of which topics is treated at 
length. The properties and uses of shales are 
next taken up and with them feldspar is placed 
