Extending the methods of Kihara and of Alder and Pople forB3and using a machine procedure forB4, we have calculated the virial coefficients for a potential with a hard core and a linear, finite attractive well. A comparison of these results with the SW and LJ potentials reveals distinctions which become more marked as one goes to higher coefficients. ForB3the TW is systematically closer to the LJ and this result is interpreted by analysis of the contributions made toB3by collision situations ranging from three particles in the attractive well to three in the repulsive field. A nonzero force is seen to be necessary if the detailed behavior ofB3is expected. ForB4larger differences were noted and the sohyphen;called ``area rule'' was not obeyed even approximately, in contrast toB3. The critical constants were computed by truncating the series atB4, and the results compared to those for a SW and a LJ.
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