Complete set of gases

There are a great many collectors in the world. Someone collects rare butterflies, someone - caps from beer bottles, still someone - stamps from the times of the USSR. All these are quite common types of collecting, because there are a lot of philatelists and numismatists. But there are also people who collect, for example, chemical elements, trying to collect at home the most complete collection of elements of the periodic table. & Nbsp; <br> <br> For known reasons (the decay of some elements occurs in thousandths of a second), it will not be possible to assemble a complete collection of elements. But there are people who have come closer to the ideal, having collected the maximum that is possible. One of these people is Theodore Gray. & Nbsp;