I came across a few free online cactus and succulent journals. All make their back issues available for download.
Xerophila — a bilingual magazine, in Romanian and English. You may need to download the PDFs to read them; viewed online, the text in one language is overlaid on top of the other, making it unreadable.1 Special Issue #5, February 2015, is of particular interest. It’s devoted to the volcanic Rangitoto and White Islands in New Zealand:
… Claude Sarich, a sulphur miner working on White Island in 1931–32, left a vivid description: “The worst hell on earth, a place where rocks exploded in the intense heat, where men had to wear wool instead of cotton because cotton just fell apart in just a couple of hours, where they had to clean their teeth at least three times a day because their teeth went black, and where the land shook violently and regularly sending rocks flying through the air”.
Schütziana — Devoted to the genus Gymnocalycium.
Addendum: A curious historical note from a biography of German cactus grower Walther Haage:
In the Third Reich the “non-Aryan” cactus had to live underneath the tables.