The values 1437 and 3031 cm.-1 were used twice, for a total of 14 wavenumbers.The first three values in this list (below 600 cm.-1) were taken from Crowder (2), and the remaining values were taken from Moritz (6). The methyl thiocyanate molecule has seven atoms and therefore has 15 fundamental vibrational frequencies. Vapor state infrared frequencies are available for all 15 except for the methyl torsion, for which no experimental value is available, and the symmetric C-S-C stretch, for which the liquid state value is available. However, the methyl torsional frequency is not needed for calculation of the thermodynamic functions because the barrier to internal rotation has been determined from the microwave spectrum. Also, it is unlikely that the vapor state frequency for the C-S-C stretch would differ enough from the liquid state value of 674 cm.-1 to affect the calculated thermodynamic properties appreciably, especially at the lower temperatures.