PREFACE. 



THE important bearings of the laws of heat, particularly in 

 reference to the physical condition of matter, have led to their 

 consideration before the chemical properties of substances, in 

 this as in most other elementary treatises on chemistry. Light 

 is then shortly considered, chiefly in reference to its chemical 

 relations. The principles of its Nomenclature, in which com- 

 pared with many sciences, chemistry has been highly fortunate, 

 are then explained, together with the Symbolical Notation in 

 use, by means of which the composition of highly compound 

 bodies is expressed with the same palpable distinctness, which 

 in arithmetic attends the use of figures, in place of words, for 

 the expression of numerical sums. 



A considerable section of the work is then devoted to the 

 consideration of the fundamental doctrines of chemistry, under 

 the heads of Combining Proportions, Atomic Theory, Doctrine 

 of Volumes, Isomorphism, Isomerism, Constitution of Salts, 

 and Chemical Affinity, including the propagation of this action 

 through metallic and saline media, in the voltaic circle. 



The materials of the Inorganic world are then described, 

 under the two divisions of non-metallic elements and their com- 

 pounds, and metallic elements and their compounds. 



Lastly, the numerous compounds of the Organic world are 

 discussed. In this department, a most extraordinary progress 

 has been made within a very short period. The study of or- 

 ganic chemistry has also been much facilitated by classification, 



