(\mathrm{Bi}{2-x} \mathrm{~Pb}{x} \mathrm{Sr}{2} \mathrm{Ca}{1-x} \mathrm{Y}{x} \mathrm{Cu}{2} \mathrm{O}{8+\delta}(0 \leq x \leq 1)) of structural type (\mathrm{Bi}(2212)) is a very interesting solid solution since we are able to adjust the critical temperature over a large range of (x) by mean of a mere formal exchange of charge between cations which do not belong to the essential (\left[\mathrm{CuO}{2}\right]{\mathrm{s}}) planes. X-ray absorption spectroscopy was performed at bismuth, lead, and copper (L{3}) edges on the (\mathrm{Bi}{2-x} \mathrm{~Pb}{x} \mathrm{Sr}{2} \mathrm{Ca}{1-x}) (Y_{x} \mathrm{Cu}{2} \mathrm{O}{8+8}(0 \leq x \leq 1)) solid solution in order to investigate the formal valence states of the elements and the correlation between hole density on the (\left[\mathrm{CuO}{2}\right]{\mathrm{p}}) planes and superconducting properties. It is shown that lead substitution does affect the role of the ([\mathrm{BiO}]{\infty}) planes which exchange electrons (holes) with the (\left[\mathrm{CuO}{2}\right}{\infty}) planes. The decrease of the hole density in the (\left[\mathrm{CuO}{2}\right]{\infty}) planes with increasing (x) has been correlated to the decrease of (T{\mathrm{c}}) 's, whereas the rapid decrease of the diamagnetic volume for (0.3 \leq x \leq 0.7) has been understood on the basis of a segregation between bismuth- and lead-rich phases. 1993 Academic Press. Inc.