70 PRINCIPLES OF CHEMISTRY. 



which will be mentioned in connection with the different substances 

 to be considered in this book. 



By adopting this mode of studying chemistry the student will soon 

 acquire a fair knowledge of chemical facts, yet he might know little 

 of the science of chemistry. In order to acquire this latter knowl- 

 edge he should study not only facts, but also the relationship existing 

 between them and between the laws governing the phenomena con- 

 nected with these facts. It is by this method only that the science 

 of chemistry can be successfully mastered. 



QUESTIONS. 81. Why are not all the elements of equal importance ? 82. 

 State the physical and chemical properties of metals. 83. How are metals 

 distinguished from non-metals ? 84. What relation often exists between the 

 atomic weights of elements belonging to the same group ? 85. Explain the 

 term allotropic modification. 86. Mention some elements capable of existing 

 in allotropic modifications. 87. What relation exists between the properties 

 of elements and the properties of the compounds formed by their union ? 88. 

 In which cases are the syllables mono-, di-, tri-, tetra-, and penta- used in 

 chemical nomenclature? 89. What use is made of the syllables ous and ic, 

 ite and ate, in distinguishing compounds from each other? 90. What are the 

 principal features of the periodic law ? 



