Now no one would ever claim, and I certainly wouldn’t claim, that I knew how every chemical was made, what it was useful for, what it cost, where the minerals came from and so forth; there was a learning curve.

So I started in a simple-minded way. I went to Chemical and Engineering News, which is the house magazine of the American Chemical Society and a wonderful weekly magazine. And every year they have summaries of productions of chemicals and summaries of firms. Out of these... you’ve got many of the firms would be making organic dyestuffs for example, or some pharmaceutical compound, which are very important, but they’re not inorganic chemistry.

So out of this list I got, I think, 484 companies, which were making inorganic chemicals. And I wrote to each of them and asked, what do you make, how do you make it, what’s it used for? And as you can imagine I got a lot of replies, company brochures, some fascinating stuff, I learned a tremendous amount from it, much of it was not relevant to what I wanted.

But it did mean that each time I was talking about a particular element and its particular compounds, I had a sound background of reality from the industry as to where these things came from. So that was important and I wanted some of the production figures and how it changed in time, for example, to come out, so that was one aspect.