68 LITHOLOGICAL GEOLOGY. 



Phosphate of lime 



Carbonate of lime 



Carbonate of magnesia 



Sesquioxyd of iron 



Alumina 



Silica 



Organic material 



Water 



Lime of organic part.... 

 Chlorid of sodium 



1. 



2. 



3. 



4. 



5. 



6. 



Burdie- 



Fife- 



Burdie- 



Burdie- 



Kosch- 



Oberlan- 



house. 



shire. 



house. 



house. 



titz. 



geuau. 



9.58 



63.60 



85.08 



83.31 



50.89 



15.25 



61.00 



24.25 



10.78 



15.11 



32.22 



4.57 



13.57 



2.89 









2,75 



6.40 



trace 







2.08 

 6.42 





| 4 13 



trace 



0.34 



0.29 



0.14 







3.38 



3.95 



1.47 



7.38 



74.03 



5.33 



3.33 









1.44 

 1.96 



100.01 97.45 100.15 100.18 99.13 100.00 



Analysis of the shell of the recent Lingula ovalis, according to T. S. Hunt 

 (Am. Jour. Sci. [2] xvii. 237) : — Phosphate of lime, 85.79, carbonate of lime, 

 11.75, magnesia, 2.80 = 100.34, — or very near the composition of bones. The 

 shell of species of Orbicula and Conularia was found to have the same com- 

 position. 



78. (4.) Carbonaceous. — Mineral coal is essentially carbon, combined usually 

 with bitumen or some kind of bituminous substance, and more or less earthy 

 substance (the ash). The varieties are — 



A. Anthracite. — Containing no bituminous matter. A hard, lustrous coal, 

 breaking with a conchoidal fracture and clean surface, and burning with very 

 little flame, as the coal of Lehigh, Wyoming, and other places of central Penn- 

 sylvania, also that of Rhode Island. 



B. Bituminous coal. — Containing bituminous substances, and therefore burn- 

 ing with a bright flame. Softer than anthracite, less lustrous, often looking a 

 little pitchy. The amount of bituminous substances varies from 10 to 60 per 

 cent., and occasionally reaches 72 per cent. Among the kinds of bituminous 

 coal there are — 



a. Caking Coal. The common variety when caking in the fire from the 

 exuding bitumen. 



b. Cunnel Coal. A very compact coal, with an even texture, smooth, clean, 

 and nearly dull surface, and a conchoidal fracture. The dull lustre gives it the 

 aspect often of being impure, when not so. The proportion of bitumen is 

 large. 



c. Asphaltic Coal. A black and very lustrous coal, looking like pure asphaltum 

 or mineral pitch. From the Albert mine, Nova Scotia. Four per cent, soluble 

 in ether, and thirty in turpentine. 



C. Lignite is a black or brownish-black coal, having an empyreumatic odor 

 when burned, and usually retaining something of the texture of the original 

 wood. It is sometimes called brown coal. It belongs to secondary and more 

 modern deposits. Jet is a very compact, black, and lustrous lignite. Peat is an 

 imperfect coal, made mainly from mosses in swamps after a long burial and a 

 partial alteration of the material. It is sometimes entirely converted into 

 coal. 



