CHAPTEK X. 



A FEW OF THE GREAT PROBLEMS OF CHEMISTRY. 



Force merges into force, 



The atom seeks its kind ; 

 The elements are one, 



And each with all combined. 



F. T. Palgrave. 

 O Lavoisier, master great, 



We mourn your awful fate, 

 But never tire of singing to your praise. 

 You laid foundations true, 

 And we must trace to you 

 The chemistry of our enlightened days. 



Anon. 



THE science of modern chemistry lias been created 

 during the present century, but its phenomena and laws 

 are so complex that it presents only a few of those great 

 discoveries which are the starting points for new devel- 

 opments, and which can at the same time be popularly 

 described. The most important of all that which con- 

 stitutes the very foundation of chemistry as a science 

 is the law of chemical combination in multiple propor- 

 tions, together with the atomic theory which serves to 

 explain it. 



The fact of chemical combination in definite propor- 

 tions was suspected by some of the older chemists, but 

 Dalton, in the early years of this century, was the first to 

 establish it firmly as a general principle, and to explain 

 it by means of a comparatively simple theory. To illus- 

 trate by examples, it is found that the two gases, nitrogen 



