THE NEWS OP SCIENCE. A Curious Alr-Deposlt. Inder the e oping of the balustrade surrounding the stone gallery nt the base nf the dome of ht Paul s In Lou. don. Is a black eleposlt nbout three-foutth three-foutth or nn Inch In thickness This deposit resembles boiler si tie nnd It has latel been subjected to chemical (iiial)sls to determine Its nature Tho mini) sis icveals the curious fact that It in n sulphate of llnie, or g)psiini nnl It Is assumed b) the chemists that It was elcposlted b) the air Their argil, ment Is that In Srto veins the smoke an I gases from London , hliniiess Invo charred the rains with sulllilent sul-phuious sul-phuious nnd rulphiirle uclds to make this deposit.