158 THE ART OF CULTURE. 



antediluvian animals, by which they are distinguished 

 from those of a later period. The bones of human 

 skulls found at Pompeii contain as much fluoric acid 

 as those of animals of a former world, for if they be 

 placed in a state of powder in glass vessels, and 

 digested with sulphuric acid, the interior of the 

 vessel will, after twenty-four hours, be found power- 

 fully corroded (Liebig) ; whilst the bones and teeth 

 of animals of the present day contain only traces of 

 it. (Berzelius.) 



De Saussure remarked, that plants require unequal 

 quantities of the component parts of soils in different 

 stages of their development ; an observation of much 

 importance in considering the growth of plants. 

 Thus, wheat yielded j^^ of ashes a month before 

 blossoming, ^§§5 while in blossom, and i?§q after the 

 ripening of the seeds. It is therefore evident, that 



phate of magnesia and fiuate of lime. By acting upon calcined bones 

 with sulphuric acid fluoric acid is disengaged. The following analyses 

 of the bones of man and horned cattle, are given by Berzelius. 



Human bone. Ox bone. 

 Cartilage soluble in water, . . . 32.17 > 33 30 



Vessels, . . . . . . .1.13j 



Subphosphate, and a little fluate of lime, . 53.04 57.35 



Carbonate of lime, . . . .11.30 3.85 



Phosphate of magnesia, .... 1.16 2.05 



Soda and very little muriate of soda, . 1.20 3.45 



100.00 100.00 



The bones of man contain three times as much carbonate of lime as 

 those of the ox, and the latter are richer in phosphate of lime and 

 magnesia in the same proportion. 



The following are the relative proportions of phosphate and carbonate 

 of lime in bones of different animals, according to De Barros. 



Phosphate of Lime. Carbonate of Lime. 



Lion, 95.0 2.5 



Sheep, .... 80.0 19.3 



Hen, 88.9 10.4 



Frog, .... 95.2 2.4 



Fish, 91.9 5.3 



100.0 100.0 



