Column density distribution functions of \ion C4 with 12.05 \leq \log ( N ) \leq 14.35 and \ion Si4 with 11.70 \leq \log ( N ) \leq 13.93 have been obtained using 81 \ion C4 absorbers and 35 \ion Si4 absorbers redward of the { Ly } \alpha forest in the lines of sight to seven quasars with 2.518 \leq z _ { em } \leq 3.78 .
These distribution functions have been directly integrated to yield ion densities at z = 3 to 3.5 of \Omega _ { C~ { } IV } = ( 2.0 \pm 0.5 ) \times 10 ^ { -8 } and \Omega _ { Si~ { } IV } = ( 7.0 \pm 2.6 ) \times 10 ^ { -9 } with { H } _ { 0 } = 65 ~ { } { km s } ^ { -1 } { Mpc } ^ { -1 } and q _ { 0 } = 0.02 ( 1 ~ { } \sigma errors ) .
A larger sample of 11 quasar lines of sight was used to measure \ion C2/ \ion C4 , \ion Si3/ \ion Si4 , and \ion N5/ \ion C4 ratios , which suggest that \ion C4 and \ion Si4 are the dominant ionization stages and that corrections to \Omega _ { Carbon } and \Omega _ { Silicon } are no more than a factor of two .
Normalizing the \alpha -process elements to silicon and the Fe-coproduction elements to carbon gives a density of heavy elements in these forest clouds of \Omega _ { metals } = ( 3.3 \pm 0.8 ) \times 10 ^ { -7 } ( { H } _ { 0 } = 65 , q _ { 0 } = 0.02 ) .
The implications for the amount of star formation and for the ionization of the IGM prior to z = 3 are discussed .