CHEMICAL ACHIEVEMENT AND HOPE FOR THE 



FUTURE^ 



By Linus C. Pauling 

 California Institute of Technology 



The past hundred years have witnessed tlie transition of chemistry 

 b'om an essentially empirical and descriptive science to a largely 

 exact and theoretical one. One hundred years ago the properties of 

 many chemical substances had been investigated, the difference between 

 elements and compounds had been recognized, analytical chemistry 

 had been developed to such an extent as to be a reliable tool, many 

 methods of synthesis of inorganic and organic substances had been 

 discovered, and tlie foundations had been laid for an extensive chem- 

 ical industry. However, the correct atomic weights of the elements 

 had not yet been generally accepted, so that the formula of water was 

 still written as HO by many chemists. The idea of valence had not 

 yet been formulated : it was not until 5 years later that the statement 

 was first made (by E. Frankland in England) that atoms have a 

 definite combining power, which determines the formulas of com- 

 pounds. The first structural formulas for molecules were not drawn 

 until 1858, when Archibald S. Couper introduced the idea of the 

 valence bond ; in the same year August Kekule, in Germany, showed 

 that carbon is quadrivalent. During the next half century chemistry 

 developed very rapidly, to become the great science — and powerful 

 art — that it is today. 



HISTORY OF CHEMICAL THERMODYNAMICS 



In 1847 J. Willard Gibbs, whom Wilhelm Ostwald has called the 

 founder of chemical thermodynamics, was a child 8 years old. The 

 first law of thermodynamics — the law of conservation of energy — had 

 not yet been accepted by physicists, although Joule had recently made 

 his determination of the mechanical equivalent of heat. It was not 

 until a year later, in 1848, that Hermann Helmholtz recognized the 

 importance of Joule's work and followed its implications through 

 various problems in chemistry, physics, and biology. The second law 

 of thermodynamics had been formulated by S. Carnot in 1824, but 



1 Reprinted by permission from The Centennial of the Sheffield Scientific School, Yale 

 University Press, 1950. 



225 



