Thanks Ole-Bob and others, for your comments how to start with CG making. Especially the drawing of Ole Bob's elektrode holder I copied on paper and will study that. Probably next week I will pick up a CG generator from a friend who bought one from the US, we can use that here with an extra trafo 100->220V. It probably is such an arc CG generator. I will see how the elektrodes are placed and certainly will follow your advice. Even making the holder will not be to difficult. Thanks for the help and the offer about the pyrex tubes. If I'm unable to obtain them here I'll let you know. RB