CONTENTS xv 



APPENDIX III 



MOLECULAR FREE PATHS 



SECTION pAQE 



26*. PROBABILITY OF A MOLECULAR FREE PATH OF GIVEN MAGNI- 

 TUDE ......... 407 



27*. PROBABILITY OF AN ENCOUNTER 409 



28*. NUMBER OF ENCOUNTERS 410 



29*. MEAN COLLISION-FREQUENCY ACCORDING TO MAXWELL'S LAW 413 



80*. COLLISION-FREQUENCY IN MIXED GASES 415 



31*. NUMBER OF MOLECULAR COLLISIONS IN A CURRENT OF GAS 418 



32*. COLLISION-FREQUENCY OF A PARTICULAR MOLECULE . . 420 



33*. MOLECULAR FREE PATH 422 



34*. CORRECTION OF THE FORMULA BY ALLOWING FOR THE DIMEN- 

 SIONS OF THE MOLECULES ...... 423 



35*. INFLUENCE OF COHESION ON THE FREE PATH . . . 425 



36*. FREE PATH IN MIXED GASES 427 



37*. FREE PATH OF A PARTICLE WITH A GIVEN SPEED . . . 428 



38*. DIFFERENT MEAN VALUES OF THE FREE PATH . . . 429 



39*. INTERVAL BETWEEN Two COLLISIONS 432 



40*. CALCULATION OF THE PRESSURE 433 



41*. NUMBER AND MEAN COLLISION-IMPULSE OF THE COLLIDING 



PARTICLES 436 



42*. ANOTHER CALCULATION OF THE MEAN FREE PATH . . 436 



43*. PRESSURE OF AIR IN MOTION 437 



APPENDIX IV 

 VISCOSITY OF GASES 



44*. GENERAL EEMARKS ON VISCOSITY 439 



45*. THEORY OF VISCOSITY ON THE ASSUMPTION OF EQUAL SPEEDS 



FOR ALL MOLECULES 439 



46*. CALCULATION OF VISCOSITY ON? THE ASSUMPTION OF MAX- 

 WELL'S LAW OF DISTRIBUTION OF SPEEDS . . . 444 

 47*. CALCULATION FROM MAXWELL'S GENERAL LAW . . . 446 

 48*. INVESTIGATION AND DEVELOPMENT OF THE FORMULA FOR THE 



COEFFICIENT OF VISCOSITY 448 



49*. FRICTION ACCOMPANYING CHANGE OF DENSITY . . . 452 



50*. EXTERNAL FRICTION 454 



