308 Domestic Science 



Exercise for Student. 



As far as your knowledge serves, show that the substances stated 

 to be non-metallic elements do not agree with the metals in their 

 qualities. 



. 211. The classification of compounds is not so 

 simple a matter as that of elements. Some 200,000 

 distinct compounds are known to chemists, and the 

 methods of classification adopted are arranged to suit 

 the requirements of various special properties or groups 

 of properties according to the purpose of the classifi- 

 cation. It was formerly supposed that one great 

 natural line of demarcation could be drawn between 

 bodies produced by animals and plants as the results 

 of vital processes and those bodies naturally belonging 

 to the world of " dead " things. Thus compounds were 

 classified as " organic " or " inorganic ", and this 

 arrangement presents some advantages even at the 

 present day. Organic bodies all contain carbon. The 

 combining powers of this element are somewhat 

 peculiar as compared with those of the remaining 

 elements, a much larger number of compounds con- 

 taining carbon being known than is the case with any 

 other element. Thus organic chemistry, as it was 

 termed, has now become the chemistry of the carbon 

 compounds. That the intervention of the energies of 

 living matter is a necessary factor in the production 

 of organic substances is, however, now proved to be 

 a fallacious idea. The discussion of the properties 

 and composition of some important organic bodies will 

 be found in Part II of this book. 



212. Another method of grouping compounds was 

 based on the number of elements contained in a mole- 

 cule of each compound. Compounds containing two 

 elements only were called "binary" compounds, and the 



