We present new high-resolution observations of Sagittarius A* at wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration with the Pie Town Very Long Baseline Array antenna .
We use the measured sizes to calibrate the interstellar scattering law and find that the major axis size of the scattering law is smaller by \sim 6 \% than previous estimates .
Using the new scattering law , we are able to determine the intrinsic size of Sgr A* at wavelengths from 0.35 cm to 6 cm using existing results from the VLBA .
The new law increases the intrinsic size at 0.7 cm by \sim 20 \% and < 5 \% at 0.35 cm .
The intrinsic size is 13 ^ { +7 } _ { -3 } Schwarzschild radii at 0.35 cm and is proportional to \lambda ^ { \gamma } , where \gamma is in the range 1.3 to 1.7 .