  The infrared through millimetre light curve of 3C 279 is investigated for the
period of 1986 until mid-1994, during which time several flares were observed.
A quiescent spectrum (identified with emission from an underlying jet) is
presented. Both the near-IR and 375-150 GHz regimes are shown to be well
described by power laws, with no evidence for any thermal contribution in the
IR. Successful isolation of the flaring component by subtraction of a base
level is found to be difficult. Dividing each individual flare into two regimes
corresponding to before and after maximum flux, we find strong linear
correlations between log 90 GHz flux and 22-90 GHz spectral slope. Furthermore,
the gradient of the linear correlation steepens as the flare decays after
maximum. This trend is observed for several successive flares, and can be
successfully explained in terms of evolution of the flare according to the the
shocked-jet model of Marscher & Gear (1985).
