ANCESTRAL MAN. 7 



place where water was taken from the surface, water was taken 

 also from the bottom of the sea. Three examples are here given 

 of the analytical result, premising that the total average quantity 

 of solids in solution was 4,000 grams in 100,000 c.c. of water; 

 and in these 4,000 grams the amount of silica was so little as to 

 vary from 2 grams to one-tenth of a gram. 



Temperature Grams in 100,000 

 Sp. gr. Fahrenheit. c.c. of water. 



( Surface of sea 1.0268 52.6 2.10 



{Bottom, 767 fathoms ... 1.0268 41.4 1.10 



J Surface 1.0266 52.5 0.75 



( Bottom, 363 fathoms ... 1.0268 31.4 0.10 



(Surface 1.0265 49-7 °-3° 



3" \ Bottom, 640 fathoms ... 1.0262 26.6 0.10 



Now, whether the sea obtains its silicates from the felspathic 

 rocks that break its billows, or from the diatomaceous organisms 

 that perish in its depths, we should have expected to find, if there 

 were any difference at all, a larger amount of silicious matter at 

 the bottom of the sea than at the top. The reverse is the case, 

 however, in the instances just quoted. We see, too, that as the 

 specific gravity is practically uniform, and unaffected by depth, 

 the only concomitant variations are those of the temperature of 

 the water and the quantity of silica in solution. 



But if a falling temperature facilitates the deposition of silica? 

 it acts, as regards lime, in a manner precisely the contrary. For 

 the chief factors in calcification are calcium oxide (lime) and 

 carbonic acid, and it is well known that both of these substances 

 are more soluble in cold than in hot water.* 



Have we not found then, at last, the unrhythmical but recipro- 

 cating cause of which we have been in quest ? When the sea is 

 in any manner chilled, silica tends to be thrown down and lime 

 to be taken up ; and when the sea is in any manner warmed, then 

 lime is deposited and silicates are dissolved. 



II.— FLINT IMPLEMENTS. 



Flint was highly prized by aboriginal men. It possesses many 

 most valuable properties. Its edge can be made so fine and 

 keen that, for shaving hair, modern savages have preferred it to 



* One volume of water at 32 o F. dissolves 1 .797 : volumes of carbonic acid, whilst 

 at 68 ° F. only 0.901 volume is absolved at the atmospheric pressure. 



