S20 



ANNUAL REGISTER, 1794. 



earth than in itj the air is most pro- 

 bably tlie great agent in decompo- 

 sition and combination, and also a 

 certain degree of heat. Thus the 

 deeper we go into the earth, we find 

 the fewer changes going on ; and 

 there is probably a certain depth 

 wheie no change of any kind can 

 possibly take place. The operation 

 of vegetaiion will not go on at a 

 certain depth, but at this very depth 

 a decomposition can take place, for 

 the seed dies, and in time decays ; 

 but at a still greater depth, the seed 

 retains its life for ages, and when 

 brought near enough to the surface 

 for vegetation, it grows. Something 

 similar to this takes place with re- 

 spect to extraneous fossils ; for al- 

 though a piece of wood or bone is 

 dead, when so situated £s to be 

 fossilized, yet they are sound and 

 free from decomposition, and the 

 depth, joined wiih the matter in 

 which they are often found, as 

 stone, clay, &c. preserve;; them 

 frcm putrefaction, and their disso- 

 Jution requires thousands of years 

 to complete it ; probably they may 

 be under the sf^me circunistar.ces as 

 in a vacuum ; the her.t in such situa- 

 tions is uniform, probably in com- 

 mon about 52° or 53°, and in the 

 colder regions they are still longer 

 preserved. 



I believe it is generally under- 

 stood that in extraneoui* fossils the 

 animal part is destroyed ; but I find 

 that tl;is is not the case in any I 

 .have met with. 



hells and bones of fish, most 

 probably have the least in quantity, 

 baring .teen longest in that state, 

 otherwise they shouldhavethe most ; 

 for the harder and more compact 

 the earth, the better is the animal 

 part preserved ; which is an argu- 

 j^ent in proof of their having been 



the longer in a fossil state. From 

 experiment and observation, the 

 animal part is not allowed to putre- 

 fy, it appears only to be dissolved 

 into a kind of mucus, and can be 

 discovered by dissolving the earth in 

 an acid ; when a shell is treated in 

 this way, the animal substance is 

 not fibrous or laminated, as in the 

 recent shell, but without tenacity, 

 and can be washed off like wet dust; 

 in some, however, it has a slight 

 appearance of flakes. 



In the shark's tooth, or glosso- 

 petra, the enamel is composed of 

 animal substance and calcareous 

 earth, and is nearly in the same 

 quantity as in the recent; but the 

 central part of the tooth has its ani- 

 mal substance in the state of mucus, 

 interspersed in the calcareous mat- 

 ter. 



• In the fossilbones of sea-animals, 

 as the vertebrae of the whale, the 

 animal part is in large quantity, 

 and in two states ; the one having 

 some tenacity, but the other like 

 wet dust : but in some of the harder 

 bones it is more firm. 



In the fossil bones of land-animals, 

 and those which inhabit the waters, 

 as the sea-horse, otter, crocodile, 

 and turtle, the animal part is in 

 considerable quantity. In the stags 

 horns dug up in Great Britain and 

 Ireland, when the earth is dissolved, 

 the aninjal part is in considerable 

 quantity, and very firm. The same 

 observations apply tothe fossil bones 

 of the elephant found in England, 

 Siberia, and odier parts of the 

 globe : also those of the ox kind ; 

 but inovo particularly to their teeth, 

 especially those from the lakes in 

 America, in which the animal part 

 has suffered very little ; the inha- 

 bitants find little differei)ce in the 

 ivory of such tusks from the recent, 



but 



