ADDITIONAL CHEMICAL 



EXAMINATIONS. 



605 



It is to be regretted that time did not permit me to repeat these analyses on different varieties of speci- 

 mens, and by different methods. However, I am able to furnish another analysis, of a compact portion 

 of the tibia of Archseotherium, carefully freed from all extraneous matter, made with great care in Dr. 

 Genth's laboratory, and under his immediate supervision, by Dr. Francis V. Greene, which has resulted 

 very satisfactorily, and in which the fluorine was estimated by precipitation. 



Water, ...... 



H 





1-97 



Organic matter, ..... 







4-09 



Phosphoric acid, ..... 



P 





31-19 



Silicic acid, ...... 



Si 





0-26 



Carbonic acid, ..... 



c 





2-77 



Sulphuric acid, ..... 



s 





2-19 



Fluorine, ...... 



P 





2-46 



Chlorine, ...... 



CI 





0-02 



Lime, ...... 



Ca 





50-83 



Magnesia (with a trace of Mn), 



Mg 





1-14 



Baryta, ...... 



Ba 





1-10 



Potash, ...... 



k 





0-28 



Soda, ...... 



Na 





1-57 



Iron and alumina, 



a trace. 



99-87 



These analyses are remarkable : first, in showing the existence of a notable quantity of fluorine, 

 amounting to from 2 to 3 per cent., sufficient to etch glass very distinctly, when the bones are treated with 

 strong sulphuric acid, and gently heated : second, in proving the existence of from 2 to 4 per cent, of the 

 original organic matter, and from 31 to 37 per cent, of the phosphate of lime in the bones of animals, 

 which have been entombed in these early tertiary deposits ever since the Alps first began to lift their 

 heads out of the ocean, and in which they have been enclosed, the almost inconceivable length of time 

 that has elapsed during a vast geological epoch, in which that great mountain chain of Europe has been 

 gradually thrusting its peaks to ten or twelve thousand feet above the ocean ; and while the Andes of 

 South America, during the same period, have attained probably even a greater elevation. 



Reflecting on the origin of the fluorine discovered in these Nebraska fossil bones, it becomes a question 

 whether it is an original constituent of the bones of the living animal, or has been introduced into their 

 composition after death. Since the analysis of the bones of existing animals indicates but a mere 

 trace of fluorine, it seems more probable that that element has been introduced as fluoride of calcium 

 by infiltration during the gradual process of fossilization, after the manner of pseudomorphism in minerals, 

 the fluoride of calcium gradually replacing the organic matter, as transformation proceeded, than that it 

 should have been an original constituent of the bones of the living animal. Still, the subjoined analyses 

 of the enclosing matrix gives no evidence whatever of the existence of fluorine in these deposits now. 



If the fluorine has really been derived from these deposits, we are forced to the conclusion that it has 

 all been removed by the process of pseudomorphism. May we not, however, rather look to the saline 

 waters, now common in that country, as the source of the fluorine ; or, perhaps, to the waters of the lake, 

 bay, or estuary, in which the bones may have lain macerating, previous to their long interment ? 



It is worthy also of note that Dr. Greene's analysis shows the presence of sulphate of baryta in the 

 compact portion of the bone he analyzed ; and Dr. Genth discovered minute crystals of sulphate of 

 baryta in the cavities of some of the bones by the aid of a strong magnifier. 



