Clays and clay industries of Pennsylvania
By: by Thomas C. Hopkins
Contributors: Affelder, William L.
Series: Official docs -- no. 21, 22, 23
Publisher: Pennsylvania State College
Published: 1897
Place of publication: State College, Pa
Language: eng
Subjects: Clay; Clay industries
Notes: Appendix to the Annual report of the Pennsylvania state college for 1897, 1898-99, 1899-1900.

"The clay industries of Allegheny county. By William L. Affelder": p. 134-162.
Table of contents: title: I. Clays of western Pennsylvania (in part); title: II. Clays of southeastern Pennsylvania (in part); title: III. Clays of the Great valley and South mountain areas.