SOME OF THE LATEST ACHIEVEMENTS OF SCIENCE. 



By Sir William Crookes. 



[ExtTiu-t from address of Sir William Crookes, president of the British Association for the Advauce- 

 nient of Science, at Bristol meeting, 1898.] 



•X * * Having kept 3^011 for the last half hour rigorousl}- chained 

 to earth, disclosing dreary possibilities, it will be a relief to soar to 

 the heights of pure science and to discuss a point or two touching its 

 latest achievements and aspirations. The low-temperature researches 

 which l)ring such renown to Professor Dewar and to his laboratory in 

 the Ro3"al Institution have been crowned during the present year by 

 the conquest of one of nature's most defiant strongholds. On the lOth 

 of last May Professor Dewar wrote to me these simple but victorious 

 words: "This evening I have succeeded in liquefying both hydrogen 

 and helium. The second stage of low-temperature work has begun." 

 Static hydrogen boils at a temperature of 238° C. at ordinary pres- 

 sure and at 250° C. in a vacuum, thus enabling us to get within 23° of 

 absolute zero. The density of liquid h3'drogen is onl}" one-fourteenth 

 that of water, yet in spite of such a low densitv it collects well, drops 

 easily, and has a well-defined meniscus. With proper isolation it will 

 be as eas}^ to manipulate liquid h^^drogen as liquid air. 



The investigation of the properties of bodies brought near the abso- 

 lute zero of temperature is certain to give results of extraordinary 

 importance. Alread}" platinum resistance thermometers are becoming 

 useless, as the temperature of boiling h^'drogen is but a few degrees 

 from the point where the resistance of platinum would be practicalh^ 

 nothing or the conductivity infinite. 



Several years ago I pondered on the constitution of matter in what 

 I ventured to call the fourth state. I endeavored to probe the tor- 

 menting m3^ster3^ of the atom. What is the atom? Is a single atom 

 in space solid, liquid, or gaseous? Each of these states involve ideas 

 which can onl3^ pertain to vast collections of atoms. Whether, like 

 Newton, we tr3^ to visualize an atom as a hard spherical bod3% or, with 

 Boscovitch and Faradav, to regard it as a center of force, or accept 

 the vortex atom theory' of Lord Kelvin, an isolated atom is an unknown 

 entit3" difficult to conceive. The properties of matter — solid, liiiuid, 



143 



