selected at various distances of separation to be followed from frame to frame 
over time. In each frame the scalar distance between the floats as well as their 
separation along two perpendicular vectors (x and y) was obtained. These data 
were then analyzed using the relationship given by Batchelor (1950). 
where 
is the initial scalar distance between floats 
£ is the initial distance between the floats 
A 1 
projected on the x axis 
C is the distance between the floats after some 
"z • 
time, t, projected on the x axis 
e is the rate of turbulent energy flux 
The same operation was carried out for the *y* vector which should yield a 
similar value if the turbulent field is isotropic. Unfortunately, it is extremely 
difficult to extend the analysis to a third dimension and it is not practical to 
use the method to explore the horizontal turbulent field below the surface. 
Additional Relative Turbulence Measures 
As discussed earlier, the flux of turbulent energy influences the rate at 
which materials may be exchanged across a laminar boundary layer. This 
suggests that the dissolution rate of a solid substance placed in the water may, 
at least to some degree, be a function of the turbulent energy of the fluid. The 
importance of the turbulent effect should be greatest for materials that are 
near saturation in sea water. After some exploration, we have found that the 
mineral gypsum (CaS0 4 ) is particularly well suited for this purpose. It is easily 
obtained, inexpensive, and a large number of uniform pieces can be cut from a 
single rough block. The dissolution rate is influenced somewhat by temperature 
and salinity, but these relationships are easily established in the laboratory in 
order to compare measurements made under different conditions. Since the 
rate of weight loss is also a function of size, we have found it best to use 
standard pieces of gypsum measuring ~2.5 x 1.8 x 0.7 cm with an initial 
weight of about 6-8 gms. Blocks of this size are suitable for making 
measurements of weight loss over periods ranging from about 6-24 hrs. 
Replication appears to be quite good and duplicate blocks are hung off a fixed 
or free floating line to obtain a vertical profile of dissolution rate. 
Unfortunately, however, the CaS0 4 dissolution rate may provide only a 
relative measure of turbulent energy and it is not clear if it is possible to relate 
389 
