Table 40 {continued) 77 



PROBABLE VALUES OF THE GENERAL PHYSICAL CONSTANTS 



Henning and Jaeger 1 give as a mean value, L = 1.42892 g- 1 -1 and (1— a) 

 = 1.00092. A more recent result by Baxter and Starkweather 2 (L = 1.42901) 

 is omitted, but is included in the discussion by Henning and Jaeger, and raises 

 the mean L to 1.42893. From this, and the value of (1— a) just quoted, the 

 H.P. gets its value of v n . The more recent values of (1 —a), average 1.00086, 

 and this, taken with the Baxter and Starkweather value of L, gives v n = 22.4iig 

 X io 3 cm 3 , in close agreement with the I.C.T. value. 



Baxter and Starkweather 3 have recalculated their 1926 data in a more logical 

 manner and obtain L— 1.428965 grams per liter, (1 — a) = 1.000927. 



L= (1.428965 ±0.000030) gram • liter 1 (# = 980.616) 

 1 — a = 1 .000927 ± 0.000030. 



R - 22.4146 ± 0.0008 liter . mole" 1 (g 45 = 980.616) 

 R n = 22.4135 ± 0.0008 liter ■ mole" 1 ( gn = 980.665) 

 v n = (22.4141 ± 0.0008) x 10 3 cm 3 • mole" 1 (g H = 980.665) . 



Ratio of international (int.) to absolute (abs.) electrical units. — For prac- 

 tical convenience, the ohm, ampere, and volt have been defined, by international 

 agreement/ in terms of definite physical apparatus. 5 



These international units are to be compared with the corresponding absolute 

 units, with which they were of course identical, within limits of experimental 

 error, at the time of adoption in 1908. One abs. ohm=io 9 em units of resis- 

 tance, the em unit, under the assumption that permeability is dimensionless, 

 being one cm • sec. -1 . Measurements of the abs. ohm have been made in a variety 

 of ways, but all methods necessarily involve the measurement of length and 

 time. The abs. ampere is io" 1 em units, the em unit being one dyne 1/2 , again 

 with the assumption of dimensionless permeability. 



The definition of the int. amp. just given is the primary definition, and 

 Doctor Birge follows the I.C.T. in designating the int. amp. so defined, and all 

 quantities involving it, by the symbol "( a )-" Now let 



(1) 1 int. ohm = p abs. ohm (2) 1 int. amp. (a) — q abs. amp. 



then 



(3) 1 int. coul. (a) = q abs. coul. (6) 1 int. henry = /> abs. henry 



(4) 1 int. volt (a) = pq abs. volt (7) 1 int. gauss = g abs. gauss 



(5) 1 int. joule (a) = pq 2 abs. joule 



^.P., 2, 493. 2 Proc. Nat. Acad. Sci., 10, 476, 1924. "Proc. Nat. Acad. Sci., 14, 57, 

 1928. 4 London, 1908. 6 This book, p. xlvi et seq. 



Smithsonian Tables 



