101 Fossil Bones and Pscudo-Coprolitcs of the Crar/. 



7lh. That the proportion of nitroG^cn contained in fossilized 

 bones is only very minute ; and it is therefore clear that, durlns^ 

 the process of tossilizalion, the nitro^-enous or gelatinous jiart of 

 the bones becomes dissolved out fr»)m the (\arthy and insoluble 

 portion, or is decomposed by the oxidizing- action of the air and 

 dissipated in the form of gas.* 



Besides the above, I have also been enabled to determine 

 another interesting; fact ; nanjely, that the phosphoric acid and 

 lluorine occur in largest proportion in the external layers of the 

 pseudo-coprolites. Thus, the most external portion of one of 

 these nodules contained — 



1*105 per cent, of fluoride of calcium, and 

 40'01'J per cent, of phosphoric acid; 



whereas the central portion contained only 



O'Gll per cent, of the fluoride, and 

 31'0ir> per cent, of phosphoric acid. 



In the second specimen which was examined in this way the 

 difTcu'ences were still more strongly marked. The results were 

 as follows : — ■ 



Exterior portion, Iiilorior poilion. 



Fluoride of calcium , . . 3'9i)G . . J-DOl 

 rhosphoric acid 32-043 . . 21-040 



Now, the above results would certainly g^o far to prove the cor- 

 rectness of Dr. Bucklaud's views with regard to the mode of 

 formation of these strange fossils. According- to Drs. Buckland 

 and Playfair, the phosphoric nodules in question originally con- 

 sisted of marl-stone, chalk, or soft limestone, and becam.e impreg:- 

 nated with phosphoric acid only by long-continued contact with 

 decomposing animal exuviae and other organic matter. Lime 

 possessin<2^ a greater aflinity for phosphoric acid than it does for 

 carbonic acid, a kind of exchange of elements, or pseudomorphic 



* The same result was arrived at by M. Marcliaiid. This chemist analysed two 

 specimens ol" I he fossil bones of a species of bear : one of these (I.) had been found on 

 the suiliuc ol' (hi! soil; the other (II ), on tlie conlrary, liad been dug uj) from a 

 considcrabh! (U'ptli. The following are the results of liis analysis ; — ■ 







I. 



II. 



Organic matter 



. 4' 



•20 



16- 



-24 



Phosphate of lime . 



. G2' 



-11 



5(5" 



-01 



Carbonate of limt: . 



. 13' 



•2t 



13- 



•12 



Sulpliate of lime 





•25 



7' 



•14 



Fluoride of calcium 



! ! 2- 



-12 



I' 



•96 



Pliosphate of magnesia 



. 0- 



-50 



0- 



'30 



Silica ..... 



. 2' 



12 



2- 



•15 



Oxides of iron and manganese . 



2" 



12 



2- 



00 



Soda and loss . . 



. 1- 



-34 



1- 



08 



100- loo- 



Here it will be scon that the bone which had been exposed to the action of the air 

 contained only a little more llian one-lV)urih as much organic matter as the odier. 



