WILLARD GIBBS 343 



contrasted, for in their case it was a concentration of personal 

 powers, not a narrowness of mind that made their work so 

 diverse. Gibbs did not despise applied science, nor did Rum- 

 ford neglect theory. Each did most what he could do best, the 

 work he was fitted by nature to do, and what, in the state of science 

 at the time, was most needed. In the days of Rumford, when 

 physical science was in its infancy, one who devoted himself to its 

 prosecution had to justify such research by constantly showing 

 its value to mankind. Experiments had to be crude because 

 facilities were lacking. But in the time of Gibbs, a hundred years 

 later, the technique of experimentation had reached great perfec- 

 tion, the usefulness of scientific research had been demonstrated, 

 and there were plenty of workers in well-equipped laboratories, 

 but deep abstract thinkers were rare. Ants were numerous and 

 busy, but spiders were hard to find. 



Chemistry is in a peculiar state. It started as a practical 

 science and its advance has been so rapid that the theoretical has 

 never caught up with it. By a century of very successful experi- 

 mental work there have been accumulated a larger number of 

 verified facts than was ever before at the disposal of a science, 

 but there is an almost complete lack of guiding theories and corre- 

 lating hypotheses. Hundreds of thousands of chemical com- 

 pounds have been made and studied; their melting-points, boiling- 

 points and solubilities have been determined; their properties and 

 reactions are known ; but why they look and behave as they do no 

 one can tell. The chemist who mixes together two compounds 

 can guess only by means of vague and uncertain analogies how 

 they will act. Whether a given salt will be more or less soluble 

 in hot water than in cold, whether two solutions of salts when 

 mixed will precipitate a solid, evolve a gas or remain unchanged 

 he has no way of determining for sure except to try and see. 



A successful chemist needs the memory of a politician; he has 

 to exert himself continually to enlarge his circle of acquaintances, 

 and to remember as much as possible about their behavior under 

 all circumstances. He envies his brother physicist, who needs only 

 carry in his head a neat little collection of formulas to be able to 



