We present 10 new measurements of carbon gas phase column density in the interstellar medium. We have used spectra made with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope containing the CII 1334.5 Å and CII* 1335.7 Å lines. The continuum reconstruction method has been used to obtain the carbon column density from the Lorentzian damped lines. Extinction curve parameters are determined in selected directions and relation between C/H ratio and extinction parameters is discussed. A correlation has been found between C/H and the strength of the 2175 Å bump. Unlike previous results, we notice that C/H changes with fractional abundance of molecular hydrogen, f(H2). The average value of C/H=3.55×10-4 for lines of sight with f(H2)<1×10-3 is the same as solar photospheric abundance from Grevese and Noels (1993) and may represent the real cosmic carbon abundance.