A silicate-graphite model of interstellar extinction has been compared with recent observational information about the UV part of the extinction curve. The model has large (greater than 0.01 micron) and small (0.005 micron) grains of each composition, and the number densities of the four components are assumed to vary independently and randomly within certain limits. A total of 50 extinction curves have been generated and subjected to analysis similar to that for the UV observations. By fitting a Lorentzian profile to the 4.6/micron graphite hump, it is shown that the model produces no correlation between the central wavenumber and the profile width. This is contrary to often stated expectations for any graphite model, but in agreement with observations. Several observed correlations in the UV extinction curves can also be understood within the context of this model. It is suggested that the presence of a nongraphitic mantle on the larger silicate grains may improve the model in this respect.