As VijayaRagavan and J.R said, your sentence is incomplete.
In what context are you trying to use that information? If you are going to talk about Mr Adam and you want to mention his discovery along with his name, you need a second comma:
- Mr Adam, [who first described the properties of X], [And here other things you want to say]
When you say "who first..." you are providing additional information.
The use of the comma there would be to set off parenthetical elements. You can read more about this usage of the comma in this page, case number 4.
However if that is not your intention, if you just want to talk about him and his discovery in a paragraph, you can do it like this:
- Mr Adam (1808-1882) was the first to describe the properties of X...
You can see plenty of examples of this in Wikipedia, for example: Richard Strauss
Richard Georg Strauss (11 June 1864 – 8 September 1949) was a leading German composer of the late Romantic and early modern eras.
There is no need for the pause the comma provides. If you use the comma, it makes it seem like Mr Adam's discovery is not the main point of your sentence. It looks like you just want to add information so the reader can understand better or know more about Mr Adam, but the key component of your message is something else.
That is why everyone suggested using 2 commas. If however the discovery is the key part of what you want to say, you should directly talk about it.