In the Pijiernoid Tuff of the Campania. 811 



confirmerl by Professors Bassani and Trincliese. The bone is not 

 entire, but no doubt was so in the tuff, part having been broken off 

 in quarrying operations. It occupied a somewhat larger space than 

 requisite in its matrix, as if part of the flesh were still adherent to it 

 at the time of its burial, or, more likely, the effervescence set up by 

 the acid contained in the dust that enveloped it attacked it and 

 produced sufficient gas to distend the cavity around it. That such 

 was more probably the case is shown by enclosures of limestone 

 which have likewise effervesced, and so now occupy cavities of larger 

 volume than that of the original fragment of limestone. The bone 

 in question is fissured and cracked as if it had shrunk, due no doubt 

 to the removal of some of its organic or earthy constituents, or the 

 chemical replacement of some of them by others of less volume. 

 This bone is covered by a coffee-brown crust up to a tenth or more 

 of a millimetre thick, and consists of the following minerals, accord- 

 ing to A. Scacchi and Prof. P. Franco, of augite, hornblende, and 

 biaxial mica, and I have since detected on a small detached fragment 

 of another bone some imperfect yellowish hexagonal prisms quite 

 identical with those on the limestone enclosures, which prisms, 

 though very impure, give the microchemical reactions of nepheline. 

 This second bone was found only a few yards from the tibia, and 

 therefore could not have been exposed to any important difference 

 of temperature. It is true that it contains no organic matter, but 

 that may be due to its being an old weathered bone before its en- 

 velopment in the tuff. The same argument applies, though with 

 less force, to the ovine vertebrae from the neighbouring quarry 

 of Fossa Lupara, which contains crystals of hematite in the 

 cavities. With such spongy bones the organic matter disappears 

 much more quickly than in one of the densest parts of the skeleton, 

 sucli as the main leg bone. 



To return to the tibia— the layer of silicates crusts over both the 

 outside surface and that of the marrow cavity and, what is important, 

 the sides of the fissures, which shows that the deposition of such 

 minerals must have been some time later than the Assuring. This 

 Assuring was posterior to the envelopment of the bone in the tuff, for 

 so fragile is it in consequence of their formation that nothing less 

 than a miracle would have preserved it entire. 



The composition of this bone is very instructive. A. Scacchi 

 found that it contained : — 



Calcium orthophosphate 88"32 



Calcium fluoride 6'20 



Organic matter 5 •43 



From the researches of Heintz, Eecklinghausen, Zalesky, Hoppe- 

 Seyler, and others, the following is the mineral constitution of 

 boue : — 



• Calcium phosphate 83'889 



Calcium carbonate 13"032 



Calcium as fluorides, chlorides, etc 0-352 



Fluorine 0-229 



Chlorine 0-183 



Different bones of the same animal vary in composition, as do the 



