The original books
The publication history of this two-volume work is slightly complicated.
- 1902: volume 1 (London & Oxford)
- 1903: volume 1, revised and enlarged (Calcutta)
- 1907: volume 1, revised and enlarged (London)
- undated: volume 1, second edition, revised and enlarged (Calcutta & London)
- 1909: volume 2 (Calcutta & London)
- 1925: volume 2, second edition, revised and enlarged (Calcutta)
(includes a prefaced to the 2nd edition that is dated 1904)
The later rewriting
- 1956: Ray, P. (ed.), History of Chemistry in Ancient and Medieval India, Incorporating the ‘History of Hindu Chemistry’ by Acharya Prafulla Chandra Rāy. Calcutta: Indian Chemical Society.
This is not by P. C. Ray, but by P. Ray.
The difference between this 1956 "incorporation" and the original volumes is well described in the book review byJean Filliozat (1956), “Review of P. Ray, History of Chemistry in Ancient and Medieval India, incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray,” ISIS. Available at: http://www.jstor.org/stable/226955.