1904.] PRESCOTT — THE RoLE OF CARBON. 103 



the addition of two supplements, presents for our consideration 

 something besides the choice of man in the direction of his chemi- 

 cal research. These advancing thousands of individual combina- 

 tions, of determinate molecular weight and fixed elemental compo- 

 sition, give us evidence of the chemical productivity of carbon and 

 of its character in relation to the other elements. 



We need to keep before us the place of carbon among its rela- 

 tives in the periodic system. Central as it is in its electric polarity 

 and in the order of its valence, the leading member of a group 

 holding an equilibrium among the other groups, its place is that of 

 a balance of power. But an element, preeminently this element, is 

 more than the occupant of a place, more than a mere number in a 

 progressive system, a mere function of a weight; it is all of these 

 perhaps, but if so it is more : it is an individual. Carbon is not 

 wholly exceptional, however, neither in the sense of an entire lack 

 of the variability of neighboring elements, nor in that of being the 

 only one whose atoms can at all unite to each other in the forma- 

 tion of chains. It is by virtue of both its central position and its 

 independent character that it appears, when in combination, as the 

 element in command. 



We must recognize the fact, without explanation, that the 

 unusual ability of carbon to unite its atoms in chains is dependent 

 upon their union with hydrogen, whose aid is thereby indispensable 

 to the organic world. Carbon is formed for complexity only when 

 supported by the unvarying unity of hydrogen, and by this support 

 is provided the great capacity of carbon for extensive molecular 

 structure. 



The science of chemistry, and therefrom all physical science, has 

 been enriched by experimental studies of molecular constitution. 

 These are studies of determinate facts, and it is but a consistent 

 expression of these facts that is undertaken in structural formulae or 

 even in the atomic theory itself, as used in the work of chemists. 

 The several differences, for instance, between dimethyl ether and 

 ethyl alcohol, two individuals of the composition CgHgO, are differ- 

 ences of fact. We give statement in the figurative language of the 

 structural formula and of the atomic theory to the actual nature of 

 the one as an ether and of the other as an alcohol. It is a discov- 

 ered truth that in the alcohol one-sixth of the hydrogen is united to 

 the oxygen more intimately than the other five-sixths of the 

 hydrogen are united to the oxygen. It is a truth that in the ether 



