594 THE POPULAR SCIENCE MONTHLY. 



efforts to determine its constitution ; but, finally, that prince of ex- 

 perimenters, Baeyer, of Munich, succeeded, and indigo is to-day 

 manufactured from inert matter ; and, though this manufactured 

 article can not yet successfully compete with that obtained from 

 the plant, it is, in my opinion, simply a question of time when the 

 occupation of the plant will be gone. 



The subject of the constitution or structure of chemical com- 

 pounds at present receives more attention from working chemists 

 than any other, and this has been the case ever since chemistry 

 came to be a science. Great progress has been made, particularly 

 within the past twenty or thirty years. In this field, as in that of 

 the elements, to which I have already referred, wonderful predic- 

 tions have been made and verified. Let me here quote a passage 

 from an address by that eminent physiologist and philosopher 

 Eniil Du Bois-Reymond. He says : " I know of no more astonish- 

 ing production of the human mind than structural chemistry. To 

 develop, from that which appears to the five senses as quality and 

 transformation of matter, such a doctrine as that of the relations 

 between the hydrocarbons, could scarcely have been easier than 

 to develop the mechanics of the planetary system from the motion 

 of luminous points ; and Strecker's prediction of the synthesis of 

 creatine, which was afterward verified by Volhard, although in a 

 less exalted sphere, was in fact no smaller achievement than the 

 discovery of Neptune." 



Of late, attempts have been made to go still further into the 

 subject of structure, and to get some clew as to what we may call 

 the actual shape of the minutest particles of which all forms of 

 matter are believed to be made up. According to the prevailing 

 theory, every kind of matter is made up of certain minute par- 

 ticles called molecules, and these molecules are conceived to be 

 made up of still smaller particles called atoms. This theory is not 

 merely a wild suggestion of dreamers, but it is forced upon us 

 after a profound study of an immense number of facts. It is 

 found that the facts can be explained only on this assumption. In 

 chemical compounds it is believed that the atoms of elements are 

 united with one another to form the molecules, and that the com- 

 pounds are made up of these molecules, which are moving around 

 freely in the case of a gas, less so in a liquid, and held together in 

 solids. Now, the problem of the chemist is to determine how the 

 atoms are arranged in the molecule — or to determine what con- 

 nections exist between the atoms, without reference to the actual 

 arrangement in space. When we consider that the atoms and 

 molecules are almost infinitely small — so small, indeed, that we 

 are told that the smallest particle of matter visible with the help 

 of a good microscope must contain from sixty to one hundred mill- 

 ions of molecules — it does seem in the highest degree presump- 



