ABSTRACT
The last values were criticized by a Dutch meteorologist, C. H. D. BuysBallot, who pointed out that if the molecules moved as fast as Clausius claimed, the mixing of gases by diffusion should be much faster than had been observed. To meet this criticism Clausius wrote a second paper in 1858 introducing molecular collisions into his model, with the new parameter of mean free path to characterize the distance travelled by molecules between successive collisions.
