74 STKUCTUEAL GEOLOGY. 



rye, maize, rice, buckwheat (the amount of ash 2 per cent or less) affords 40 to 50 

 per cent; of leaves of walnut (the ash 7 to 7-72 per cent), 21-1 per cent spring, 4 per 

 cent autumn ; of beech (ash 4-8 and 6-75 per cent), 7-8 per cent summer, 4-2 percent 

 autumn ; wood of body of beech (amount of ash in dried 0-65 percent), 5-o per cent ; of 

 small wood 11-6 per cent, and of brush 12-3 per cent; of pine, fir, larch (0-3 per cent of 

 ash), 3-6 to 6 per cent of phosphoric acid. 



Carbonaceous. — The carbonaceous material of the rocks has come, as has 

 been stated, from the decomposition of plants and animals, and chiefly the 

 former. Wood contains about 50 per cent of carbon, along with 44 of oxygen 

 and 6 of hydrogen. Peat is woody material altered part way toward coal, 

 and sometimes wholly so in places. Brown coal is coal that has a dark 

 brownish powder. Bituminous coal has a black powder, and burns with a 

 bright flame ; anthracite burns with little flame. Each contains some of the 

 oxygen of the original wood, the anthracite the least. 



Mineral oil and mineral gas consist of carbon and hydrogen alone, oxygen 

 being wholly absent. They are the source of the flame of bituminous coal ; 

 they do not, however, exist in the coal, for when the coal is digested in 

 a solvent of the oil, as benzine, almost no oil is taken up ; the oil or gas is 

 produced by the heat from a compound present in the coal. Other carbona- 

 ceous substances of similar origin are asphalt, an oxidized hydrocarbon, 

 mineral resins, etc. Moreover, among the mineral resins are one or two 

 which contain sulphur. 



Alumina, magnesia, iron, soda, potash, sulphur, etc. — A few of the coal- 

 making plants, especially the Lycopods, contain much alumina in their ash, 

 and magnesia, iron, potash, soda, exist in many plants. In the decomposi- 

 tion of buried plants, these materials are partly dissolved out and carried 

 away by waters, and partly contributed to rocks. The following are some 

 analyses of the ash of plants : — 



Analyses of the ash of Lycopods (1, 2), Ferns (3 to 6), Equiseta (7, 8), Conifer (9), 

 Moss of the genus Sphagnum (10), and an Ilex (11) : — 



KG NaO CaO MgO FejOj MnjO^ AI2O3 PO5 SO3 SiOj CI 



1. Lyc. clavatum.. 31-90 2-68 4-13 5-89 6-00 — 22-20 7-30 3-55 13-01 — 



2. Lyc. clavatum . .25-69 1-74 7-96 6-51 2-30 2-53 26-65 5-36 4-90 13-94 3-13 



3. Aspl. filix 45-5 5-2 7-9 7-4 1-5 — — 20-0 6-8 22 4-6 



4. Aspid. filix 39-80 5-31 18-74 8-28 0-97 — — 2-56 5-40 4-38 14-72 



5. Osm.spicant....23-65 3-33 4-09 6-47 1-17 — — 1-76 1-29 53-00 5-82 



6. Pterisaquilina..l9-35 4-78 12-55 2-30 3-94 — — 5-15 1-77 43-65 6-20 



7. Eq.arvense 19-16 0-48 17-20 2-84 0-72 — — 2-79 10-18 41-73 6-26 



8. Eq.Telmateia... 8-01 063 8-63 1-81 1-42 — — 1-37 283 70-64 5-59 



9. Pinusabies 12-84 5-64 58-27 2-81 1-60 tr. tr. 2-60 1-60 12-55 2-06 



10. Sphag. commune. 802 12-40 3-17 4-92 6-35 tr. 5-89 1-06 4-33 41-69 12-09 



11. Ilex cassine 27-02 0-47 10-99 16-59 0-26 1-73 — 3-34 2-50 1-32 066 



Analysis 1 is by Ritthausen ; 2, Aderholt ; 3, A. Weinhold ; 4, Struckmann ; 5, 6, 

 9, Malaguti & Durocher ; 7, 8, E. Wittig ; 10, H. Vohl ; 11, F. P. Venable. 



In the analyses that have been made of Lycopods, the amount of ash is 3-2 to 6 per 

 cent in weight of the dried plant ; of Ferns, 2-75 to 7-56 per cent ; of Equisetum arvense, 



