Thanks for the link, which is useful, especially the older catalogue in a pdf file. I tried using various translation machines for your term but the only thing any of them came up with was "metallurgical glass."
If you do digitize any of the catalogues, I'd love to have copies. I'd be happy to help in any way, although my computer skills are, to be kind to myself, limited.
Where do people find this type of glass? Most of mine comes form Canada, where,as I've said a few times, its advertised as Chalet,