pattinson, mr., on the separation of lead and silver.
paul's, st., rocks of.
pearlstone.
peperino.
peron, m., on calcareous rocks of australia.
phonolite, hills of.
-laminated.
-with more fusible hornblende.
pitchstone.
-dikes of.
plants, extinct.
plutonic rocks, separation of constituent parts of, by gravity.
porto praya.
prevost, m.c., on rarity of great dislocations in volcanic islands.
prosperous hill, st.helena.
pumice, absent at the galapagos archipelago.
-laminated.
puy de dome, trachyte of.
quail island, st.jago.
quartz, crystals of, in beds nating with obsidian.
-crystallised in sandstone.
-fusibility of.
-rock, mottled from metamorphic action with earthy matter.
red hill.
resin-like ed scoriae.
rio de janeiro, gneiss of.
robert, m., on strata of iceland.
rogers, professor, on curved lines of elevation.
salses, compared with tuff craters.
salt deposited by the sea.
-in volcanic strata.
-lakes of, in craters.
sandstone of brazil.
-of the cape of good hope.
-platforms of, in new south wales.
schorl, radiating.
scrope, mr.p., on laminated trachyte.
-on obsidian.
-on separation of trachyte and basalt.
-on silex in trachyte.