petrographIc, petrographical

[Eng. petrograph(y); -ic, ical.] Of or pertaining to petrography. pě-trog'-ra-phy, s. [Pref. petro-, and Gr. graphõ =to write.] 1. The art of writing on stone. 2. The study of rocks; a scientific description of or treatise on rocks; that branch of geology which deals with the constitution of rocks; petrology. pět-ről, s. (PETROLEUM.] Chem.: CH10. A hydrocarbon occurring in the petroleum of Sehnde, near Hanover. It has not yet been isolated, being always found mixed with olefines and homologues of marsh-gas, but by treatment with a mixture of strong nitric and sulphuric acids, it is converted into a crystalline compound, trinitro-petrol, ('H, (NO2). pět-ro-lā-tum, s . [PETROLEUM.] A jelly-like substance consisting mainly of hydrocarbons, obtained from the residuum of crude petroleum. pět-ro-lēne, s. [Eng. petrol(eum); suff. -ene ( Min .).] Min.: An oil obtained by Bou ingault from asphalt, and announced by him as the liquid constituent of all asphalt. He a igned it the formula C10H16. Subsequent investigation tends to show that this is a mixture of oils.