Addenda and corrigenda as insert.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
"Chemist and Druggist" poisons guide : an encyclopaedia of poisons law. Published by Chemist and Druggist in 1951. Publication and catalogue information, links to buy online and reader comments.
obnb.uk is a Good Stuff website.