348 GREAT MEN OF SCIENCE 



direct access by our senses. All atoms proved to be built up 

 of positive and negative elementary charges of electricity in 

 a manner which is still the subject of further investigation. 

 It is easily comprehensible that so great and rapid an en- 

 largement of our knowledge (it took place mainly in the years 

 between 1894 and 1905) brought with it many new possi- 

 bilities - which also included technical, and particularly at 

 first, medical applications - but that it has also produced 

 some confusion, all of which is of great influence at the 

 present time. 



Pre-eminent among the recent results of the further in- 

 vestigation of atoms is the fact that they can be split up; this 

 can be effected by the action of very rapidly moving helium 

 atoms, such as are furnished by the X-rays. This renders 

 possible the transformation of heavy atoms into lighter ones 

 by human agency, a transformation which occurs of itself in 

 the case of radio-active elements. This, however, by no 

 means exhausts the work and scientific legacy of Hittorf and 

 Crookes; we must still add the following. 



Hittorf was the first to continue Faraday's work on 

 electrolysis to an important extent. He made a careful 

 quantitative investigation of the motion of the ions in 

 electrolytes during passage of the current, which opened up 

 the road to a knowledge of the internal constitution of elec- 

 trolytes, such for example as dilute salt solutions. Fried- 

 rich Kohlrausch began his investigations at this point and 

 obtained further success, upon which depends our present- 

 day exact knowledge of electrolytes, and the processes taking 

 place in them.^ 



^ Friedrich Kohlrausch, 1840-1910, was born at Rinteln on the Weser. 

 His father, who was a teacher at the High School, had carried out, with 

 W. Weber, the important measurements which led to the velocity of 

 hght being found as the proportionality factor for purely electiical quan- 

 tities; it was also the father who induced the son to study physics with 

 Weber in Gottingen. Friedrich Kohlrausch also later became a member 

 of the staff of this university, and then assistant professor. In the year 

 1871 he was called to the Technical High School in Darmstadt, in 1875 



