Technical historical literature is fine unless it is wrong or misleading due to later advances in science. Unfortunately, Mees begs the issue as do Mees and James. No updates to emulsion technology were made in the literature.
Mees says: One omission in the book requires explanation. A book on the theory of photography should contain a chapter on emulsion making, discussing various methods of procedure and their effect upon the finished product. The author's knowledge of this subject has been acquired in confidence, however, and he is not entitled to publish the material with the frankness which alone would justify publication.
No one has done this, ie. publish a full disclosure on emulsion making. Even Haist has published an emulsion formula with deliberate omissions in it. This is endemic in the entire literature and the readers must be aware of this. I must add to this list of Mees and Haist, the following: Wall and Baker among others including the aforementioned author and referenced in the OP.