ch. nr.] THE LA W OF EVOLUTION. 333 



molecules of sulphur and one of phosphorus, compounded 

 with ten organic molecules, of which each one contains forty 

 molecules of carbon, five of nitrogen, twelve of oxygen, and 

 thirty-one of hydrogen. Or, to reduce the statement to 

 its simplest form, — in every molecule of albumen we have 

 1,600 atomic equivalents of carbon, 150 of nitrogen, 240 of 

 oxygen, 310 of hydrogen, 10 of sulphur, and 6 of phosphorus ; 

 making a grand total of 2,316 atomic equivalents. And the 

 molecule of fibrine is still more intricately compounded. 



Thirdly, when we recollect that the simplest organic 

 matter actually existing contains not one but very many 

 albuminous molecules, and that these molecules are arranged, 

 not in the crystalloid, but in the colloid form, — in " clusters 

 of clusters which have movements in relation to one another," 

 — we see still more clearly how vast must be the quantity of 

 motion locked up within a small compass. 



Our fourth item is perhaps the most remarkable of all. 

 In the albumen-molecule, the sum of all the atomic equiva- 

 lents, except those of carbon, is 716. In order to hold these 

 in combination, only 716 atomic equivalents of carbon would 

 appear to be needed ; yet we find 1,600 equivalents. Why 

 this apparent excess of carbon ? — The answer is to be found 

 in the fact that nitrogen, unlike most other substances, 

 absorbs heat on entering into combination. To the mole- 

 cular motion which keeps it when free in a gaseous state, 

 it adds a vast quantity of molecular motion. It has been 

 calculated that the union of a pound of oxygen with nitrogen, 

 in forming nitrous oxide, is attended by the absorption of 

 enough heat to raise the temperature of 9,232 pounds of 

 water one degree Centigrade. It is probably owing to this 

 peculiarity that nitrogen, which is so inert when free, is so 

 wonderfully active when combined. Hence, too, we may 

 understand the extreme instability of such nitrogenous sub- 

 stances as gunpowder, gun-cotton, and nitro-glycerine. And 

 hence we may begin to discern the reason why nitrogen is 



