320 MODERN SCIENCE READER 



that are studied in the laboratory. We get only snap-shots 

 at them. If we could only get a series of pictures at short 

 intervals, we might, by combining these afterward, get 

 some idea of what is taking place during the act. Fortun- 

 ately, there are ways of controlling certain classes of 

 chemical acts and reducing their speed, so that observations 

 can be made during their progress; and much has been 

 learned in this way. Here is a great field for further 

 study, and it presents many unsolved problems. 



Finally, a few words about water. It is said that a well- 

 known chemist some years ago made a bet that a certain 

 company of chemists could not name a chemical subject 

 that would not, in turn, suggest to him a profitable chem- 

 ical investigation. Thereupon, after much deliberation, 

 the challenged company sugges-ted "water," on the assump- 

 tion that this has been thoroughly worked over, and does 

 not present unsolved problems. The result was a beautiful 

 investigation of some of the properties of water. Every 

 one knows that water is the most abundant substance on 

 the earth. It also plays a more important part in the 

 changes that are taking place on the earth than any other 

 substance. We are only beginning to learn how it acts. 

 That it dissolves many things is well known, but let us not 

 be misled because this phenomenon is so common and so 

 familiar. Put a little salt in water. What becomes of it? 

 It disappears. There is no solid substance in the vessel. 

 We may bandy phrases as we please, but we cannot tell 

 what has become of the salt. We can get the salt out of 

 the water by boiling the solution and letting the water pass 

 off as steam, when the salt will be left behind. As we put 

 the salt in and take it out, we have been accustomed until 

 recently to think of the salt as being present in the solution 

 as such. One of the most important advances in chemistry 

 made of late years is that which leads to the conception 

 that, in dilute solutions at least, there is little, if any, salt 

 present; that, in some way, the water decomposes it into 

 particles highly charged with electricity. These particles 



