We have observed three quasars , PKS 1127-145 , Q 1331+171 and Q 0054+144 , with the ACIS-S aboard the Chandra X-ray Observatory , in order to measure soft X-ray absorption associated with intervening 21-cm and damped Ly \alpha absorbers .
For PKS 1127-145 , we detect absorption which , if associated with an intervening z _ { abs } =0.312 absorber , implies a metallicity of 23 \% solar .
If the absorption is not at z _ { abs } =0.312 , then the metallicity is still constrained to be less than 23 \% solar .
The advantage of the X-ray measurement is that the derived metallicity is insensitive to ionization , inclusion of an atom in a molecule , or depletion onto grains .
The X-ray absorption is mostly due to oxygen , and is consistent with the oxygen abundance of 30 \% solar derived from optical nebular emission lines in a foreground galaxy at the redshift of the absorber .
For Q 1331+171 and Q 0054+144 , only upper limits were obtained , although the exposure times were intentionally short , since for these two objects we were interested primarily in measuring flux levels to plan for future observations .
The imaging results are presented in a companion paper .