Page:Outlines of Physical Chemistry - 1899.djvu/21

 OF THE r

UNIVERSITY

��OUTLINES

��OP

��PHYSICAL CHEMISTEY

��-*&•-

��FIEST PAET

FUNDAMENTAL THEORIES

��1\

��LAWS OF CHEMICAL COMBINATION AND THE

ATOMIC HYPOTHESIS

Following the example of Boyle l and of Lavoisier? we apply the term elementary to those substances which the chemist is unable to split up into simpler constituents. The substances submitted to our researches only rarely merit this appellation. In the majority of cases we deal with substances which are formed by the union of two or more elements, and constitute chemical compounds.

The formation of these compounds takes place according to well-defined laws :

1. The Law of Weight. — The weight of a compound is equal to the weight of the elements which have united to form it.

��1 The Sceptical Chynmt, 1661.

2 Nomenclature chimique, Lavoisier, Berthollet et Fourcroy, 1787.

B

�� �