HathiTrust provides digital access to a wealth of primary source materials, especially books from the 19th and early 20th centuries. It also includes federal, state, and some local government content up to the present day. Here are some examples of what you can find in HathiTrust:
American Medical Association. "Female-weakness" Cures And Allied Frauds. Chicago: The Journal of the American Medical Association, 1915.
Marsh, George P. (George Perkins), 1801-1882. Man And Nature: Or, Physical Geography As Modified by Human Action. New York: C. Scribner, 1864. [Marsh published revised editions over the next several years and these later editions also are available via HathiTrust.]
AAS Historical Periodicals includes many magazines and journals from the 19th- and early 20th centuries that are relevant to the history of science, medicine, and technology. Here are some examples (if the direct links don't work, just do a publication search in AAS with these titles).
An example:
Ali Puli. Centrum Naturæ Concentratum, Or, the Salt of Nature Regenerated for the most Part Improperly Called the Philosopher's Stone / Written in Arabick by Alipili ... ; Published in Low Dutch, 1694, and Now done into English, 1696, by a Lover of the Hermetick Science [Centrum naturae concentratum. Centrum naturae concentratum. Salt of nature regenerated.]. London: 1696.
You can use the Google Ngram Viewer to trace the frequency of the use of a particular word or phrase in books and other printed material over time.
This will not be a comprehensive search, as Google only uses those materials it has access to, but the search can give you an idea of when certain ideas entered the published arena. Here's an example for the word "nuclear."
