PART I. CHAPTER IV. 



57 



Mineralization of Organic Remains. 



meated by water charged with minute portions of calcareous, 

 siliceous, and other earths in solution. In what manner they 

 become so impregnated will be afterwards considered. If an 

 organic substance is exposed in the open air to the action of the 

 sun and rain, it will in time putrefy, or be dissolved into its com- 

 ponent elements, which consist chiefly of oxygen, hydrogen, and 

 carbon. These will readily be absorbed by the atmosphere or be 

 washed away by rain, so that all vestiges of the dead animal or 

 plant disappear. But if the same substances be submerged in 

 water, they decompose more gradually ; and if buried in earth, 

 still more slowly, as in the familiar example of wooden piles or 

 other buried timber. Now, if as fast as each particle is set free 

 by putrefaction in a fluid or gaseous state, a particle equally 

 minute of carbonate of lime, flint, or other mineral, is precipi- 

 tated, we may imagine this inorganic matter to take the place 

 just before left unoccupied by the organic molecule. In this 

 manner a cast of the interior of certain vessels may first be 

 taken, and afterwards the walls of the same may decay and 

 suffer a like transmutation. Yet when the whole is lapidified, it 

 may not form one homogeneous mass of stone or metal. Some 

 of the original ligneous, osseous, or other organic elements may 

 remain mingled in certain parts, or the lapidifying mineral itself 

 may be so crystallized in different parts as to reflect light differ- 

 ently, and thus the texture of the original body may be faithfully 

 exhibited. 



But the student will ask whether, on chemical principles, we 

 have reason to expect that mineral matter will be thrown down 

 precisely in those spots where organic decomposition is in pro- 

 gress ? The following curious experiments may serve to illus- 

 trate this point. Professor Goppert of Breslau attempted recently 

 to imitate the natural process of petrifaction. For this purpose 

 he steeped a variety of animal and vegetable substances in waters, 

 some holding siliceous, others calcareous, others metallic matter 

 in solution. He found that in the period of a few weeks, or even 

 days, the organic bodies thus immersed were mineralized to a 

 certain extent. Thus, for example, thin vertical slices of deal, 

 taken from the Scotch fir (Pinus Sylvestris), were immersed in 

 a moderately strong solution of sulphate of iron. When they 

 had been thoroughly soaked in the liquid for several days, they 

 were dried and exposed to a red-heat until the vegetable matter 

 was burnt up and nothing remained but an oxide of iron, which 

 was found to have taken the form of the deal so exactly that 

 even the dotted vessels peculiar to this family of plants, and 

 resembling those in Fig. 56., were distinctly visible under the 

 microscope. 



