A student has inquired whether the letter K was first used to represent 
Capital in the production function because a) C was already used for 
consumption; or b) in German, capital starts with a K (as in *Das 
Kapital*). 
 
I know that the Cobb-Douglas Production function was first introduced using 
C for capital and L for labor. So the student's question got me wondering 
when the tradition of using K began. 
 
Ross B. Emmett