LETTERS

摘要

I look forward to receiving each issue of New Scientist, but I was especially impressed by the articles, the tables and the tremendous amount of research that went into Andy Ridgway's report on the state of the world's supply of critical elements (14 February, p 35). You ran an earlier article on this subject in 2007, and were kind enough then to publish a letter from me (23 June 2007, p 23) in which I mentioned some historical examples, such as the near-sinking into incandescent bulb filaments of the world's osmium production (only about 2 kilograms per year in 1900), and how a crisis was averted by switching to tantalum and then tungsten filaments.