# In the Ideal Gas Law, why is the variable for Gas Constant labeled as an R?

The formula is written as PV=nRT.

Seems like they had a logical progression going on in regards to labeling for the most part:

Pressure being a P,

Volume being a V, and

Temperature being a T.

But the Gas Constant being labeled R makes no real sense. Maybe it was a random letter chosen, but I suspect the real answer might prove interesting.