MODERN CHEMISTRY. 431 



gravitation, while on the globe we inhabit it appears under 

 innumerable forms simple or compound solid, liquid, or 

 gaseous all subject to the same great law, and also to the 

 various physical conditions of cohesion and repulsion, acting 

 on like particles, and producing many of what are called its 

 secondary properties. But beyond these conditions, and 

 distinct from them to our present knowledge, comes in that 

 mighty force which we term Chemical Affinity the power 

 of attraction at insensible distances, uniting dissimilar par- 

 ticles of matter, and by its various intensity and manner of 

 action, producing the vast assemblage of material phenomena 

 which we now class under a common name. Chemistry is 

 the science which investigates this affinity, positive or rela- 

 tive, of the molecules of material substances the laws 

 which regulate their combination and separation and the 

 results of the actions and changes thus produced. It takes 

 cognizance of the great elementary forces of heat, light, and 

 electricity, in their ever constant influence on all such actions 

 and affinities ; and it may hereafter, as we have said, lead us 

 to physical relations and laws of a higher class, in which 

 these elements and the integral properties of matter are still 

 more closely blended. The science, however, is essentially 

 one of experiment ; and its eminent progress of late years is 

 mainly due to the clearer definition of its objects, and to the 

 enlarged methods and improved instruments with which 

 these are pursued. 



In describing it as the office of Chemistry to determine 

 the mutual affinities of the atoms of bodies, and the results 

 thence derived, we use the term in a sense justified by our 

 actual knowledge. The history of the Atomic theory, as 

 originally derived from the barren speculations of ancient 

 philosophy, and in our own time appropriated to the highest 

 purposes of true science, has been fully given in a preceding 

 article. Our business will be now to indicate the effect which 

 this doctrine, so applied, has had upon the whole school of 



