471 
When the bubble of explosion products has expanded to maximm 
radius, it has a potential erergy equal to PoAV r whereAV is the 
difference in volume between the bubble at maximum radius and the intact 
charge of explosive of radius Q,. The energy associated with the explo- 
sion products after emission of the shock wave can thus be estimated from 
experimental measurements of the maximum bubble radius, For TNT, it is 
known that the energy associated with the gas bubble at its first maximum 
is approximately 480 cal./gm., a figure which is 45 percent of the estimated 
energy of explosion of 1060 cal./gm. The bubble energy at the first maximum 
is quite generally about one half the energy of explosion .21/ The assumption 
that Ss = €o/ 2 , where €, is the initial shock-wave energy and € o the 
energy of explosion, makes possible the formulation of an alternative method 
of determination of G, » the initial value of the reduced energy variable. 
Making use of Eqe 8.27, we obtain 
Q, = An”) pe Ce (8.39) 
Pi 
The disadvantages of the approximate nature of Eq. 8.39 are to some extent 
minimized by the circumstance that except in the immediate vicinity of the 
charge the shock=-wave parameters are not very sensitive to the initial 
energy of the wave. 
Calculated values of the shock=-wave parameters for the underwater 
explosion of TNT at a density of 1.59 gm. /om.? are listed in Table 8.3. The 
initial pressure, p, = 37 kilebars, was calculated by Eqs. 2.4 and 2,6 and 
31/7 A. B. Arons and D, R. Yennie, Phys. Rev., 20, 519 (1948). 
