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 Archeotherium, 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, ; : < ; ‘ . ; : ; an 1:97 
Organic matter, : ‘ . ‘ : ; . ‘ = 4°09 
Phosphoric acid, : : ‘ : : : . : P = 31:19 
Silicic acid, . ‘ . Si — 0-26 
Carbonic acid, : : ; : . re ‘ . Can a7 
Sulphuric acid, ; : : S = 219 
Fluorine, : : : . A : . ‘ F — 2:46 
Chlorine, : 2 : : ‘ : ‘ ‘ Cl — 0-02 
Lime, i Ca — 50-83 
Magnesia (with a trace of Mn), ; A : : ‘ : Mg = 1-14 
Baryta, ‘ , Ba = 1-10 
Potash, 5 ; ; K = 0-28 
Soda, oe a ; Na — 1:57 
Tron and alumina, . , ‘ é ‘ : : : 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 erysia’s of sulphate of 
baryta in the cavities of some of the bones by the aid of a strong magnifier. 
