THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



FEBRUARY 1877. 



XII. A New Method of studying the Relation between the Vis- 

 cosity and Temperature of Gases. By Silas W. Holman, 

 Graduate of the Massachusetts Institute of Technology, Bos- 

 ton, Mass., U. S. A* 



THE importance of accurate experimental data on the laws 

 of gases, in connexion with the recently developed ma- 

 thematical hypotheses of Clausius, Maxwell, and others, has 

 led to much valuable research. It is hoped that the following- 

 method, with the preliminary results of the present paper, may 

 prove to be a contribution to the precise knowledge of this 

 subject. 



According to the " kinetic theory," each molecule of a gas 

 is constantly in rectilinear motion, possessing thus, in virtue 

 of its mass, a certain momentum. Hence, if we have two 

 layers of a gas moving over each other, we shall have a mutual 

 interchange of momentum, arising from the transference of 

 molecules from one layer to another, the result being a ten- 

 dency towards an equalization of the velocities of the two 

 layers. Thus is produced the effect of friction between the 

 two layers. The amount of this in any particular case deter- 

 mines the viscosity or internal friction of the gas, and is ex- 

 pressed by the coefficient of viscosity 77, which is representedf 

 by the formula 



Mm /1X 



v= 4^?'' W 



* Abstract of a paper rerd before the American Academy of Arts and 

 Sciences, June 14, 1876. Communicated by the Author* 

 t Phil. Mag. [IV.] vol. xix. pp. 19,434; vol. xx. p. 21. 



Phil. Mag. S. 5. Vol. 3. No. 16. Feb. 1877. G 



