THE CHEMICAL-COMPOSITION OF THE S-CEPHEIDS .3.

The hypothesis about s-Cepheids' first time crossing of the instabilit y strip is checked by spectroscopic testing. On the basis of CCD spect ra analysis, we have derived the abundances for seven s-Cepheids. The following results have been obtained: 1) V473 Lyr, IR Cep, UY Mon, BY Gas, V636 Gas have solar iron abundance, while V526 Mon and V924 Cyg s how moderate iron deficiency. 2) The absolute carbon deficiency (relat ively to the solar (C/H) value) found for all program stars (excepting V636 Gas) and a nitrogen overabundance show that these s-Cepheids are not crossing the instability strip for the first time. 3) Similarly t o previously investigated Cepheid V1162 Aql, V636 Cas also demonstrate s rather high carbon content. The plausible explanation of this phenom enon is that this star is crossing the instability strip for the first time. 4) Na and Al are overabundant for all program stars where these elements were measured. Sodium overabundance takes place also for two first- time crossing Cepheids. Possibly such an overabundance arises during the main-sequence phase. 5) alpha-elements show practically sol ar ratios with respect to Fe. 6) For iron-group elements the (M/Fe) va lues are close to the solar ones. 7) s-process elements are perhaps sl ightly enhanced in the program stars. The results of the present paper are discussed together with the results of the recent paper by Andrie vsky et al. (1995) devoted to s-Cepheids.