KOCKS : THEIR CONSTITUENTS AND KINDS. 



73 



calcareous deposit, the solution converts the calcareous rock into calcium 

 phosphate, which goes also by the name of guano. Isolated, excrements in 

 rocks are called coprolites. 



Analyses of bones: 1, 2, human bones, according to Frerichs; 3, fish (Haddock), 



according to Dumenil ; i, Shark (Squalns cornubicus), according to Marchand ; ^, fossil 



bear, id. : — 



1. 2. 3. 4. 5. 



Calcium phosphate 50-24 59'50 55-26 32-46 62- 11 



Calcium carbonate 11-70 946 6-16 ) , , , 13-24 



^ 4"44 

 Calcium sulphate — — — j 12-25 



Organic substance 38-22 30-94 37-63 58-07 4-20 



Traces of soda, etc — — 1-22 3-80 — 



Calcium fluoride — — — 1-20 2-12 



Magnesium phosphate — — — 1-03 0-50 



In No. 4, a little silica and alumina are included with the fluoride. No. 5 contains also 

 silica 2-12, and oxides of iron and maganese, etc., 3-46. 



The enamel of teeth contains 85 to 90 per cent of calcium phosphate, 2 to 5 of calcium 

 carbonate, and 5 to 10 of organic matters. Fish-scales from a Lepidosteus afforded Fremy 

 40 per cent of organic substance, 51-8 of phosphate of lime, 7-6 of magnesium phosphate, 

 and 4-0 of calcium carbonate. Other flsh-scales contained but a trace of the magnesium 

 phosphate and more of organic matters. 



T. S. Hunt obtained for the composition of the shell of Lingida ovalis, Calcium phos- 

 phate 85-79, calcium carbonate 11-75, magnesium phosphate 2-80 = 100-34. The shells of 

 a fossil Obolus afforded Kupffer the composition nearly of a fluor-apatite (Amer. Jam: 

 Sci., III. vi. 146); and the phosphatic shells are thin, somewhat horny in appearance, and 

 usually become black on fossilization. 



The shell of a Lobster {Palinurus) afforded Fremy, calcium carbonate 49-0, calcium 

 phosphate 6-7, organic substance 44-3. 



Phosphatic nodules, possibly coprolitic, in the Lower Silurian rocks of Canada (on 

 River Ouelle), afforded T. S. Hunt (see Amer. Jour. Sci., II. xv. and xvii.), in one case, 

 calcium phosphate 40-34, calcium carbonate with fluoride 5-14, magnesium carbonate 9-70, 

 iron peroxide with a little alumina 12*62, sand 25-44, moisture 2*13 = 95-37. In a hollow 

 cylindrical body from the same region, there were 67 -53 per cent of phosphate. 



Analyses of coprolites. — Nos. 1 and 2 by Gregory and Walker ; 3 and 4 by Council ; 

 5 by Quadrat ; 6 by Rochleder (a coprolite from the Permian) : — 



1. 2. 3. 4. 5. 6. 



Burdie- Fife- Burdie- Burdie- Kosch- Oberlan- 



house. shire. houBe. house. titz. genau. 



Calcium phosphate 9-.58 63-60 85-08 83-31 50-89 15-25 



Calcium carbonate 61-00 24-25 10-78 15-11 32-22 4-57 



Silica "I trace 0-34 0-29 0-14 — 



Organic material I 3-38 3-95 1-47 7-38 74-03 



Magnesium carbonate 13-57 2-89 — — — 2-75 



Iron sesquioxide 6-40 trace — — 2-08 — 



Alumina — — — — 6-42 — 



Water 5-33 3-33 _ _ — — 



Lime of organic part — — — — — 1'44 



Sodium chloride — — — — — 1-96 



100-01 97-45 100-15 100-18 99-13 100-00 



The ashes of grass, straw, clover, amounting to 5 to 8 per cent of the dried plant, 

 afford usually 5 to 15 per cent of phosphoric acid ; and those of the seed in wheat, 



