The frixion/friction pens disappear at a temperature of about 60 to 65 degrees , and that's because, there are three liquids (?) in it, two combine when drawing, but when it get's heated one does a reactions, so that the two liquids can't combine anymore. And so it disappears. But it reappears at a really cold temperature (under -10 °C). It was a project of the intoMINT App I had seen in their Instagram story. I tried it out, and it worked, even though it's not visible like at the beginning, but maybe I just had to lay it into the freezer for the whole day. But - you should not use it to sign important documents.
Ayearagotoday is written in HTML ... or at least the entry format codes.
Leibnitz wasn't just for Theologia, but also a big part in mathematics! He developed the "binäre Zahlensystem", "Integral- & Differenzialrechnung" and even ingenieurs had problems with understanding his theories!....But without him modern technology wouldn't be as it is today.
