Its Use and Importance—What it is—How it Differs from Physics—Its Divisions—Distinction between Theoretical and Practical Chemistry—Outline of Theoretical Chemistry—Laws of Chemistry—Atomic Theory—Chemical Notation—Molecular Weights—Reactions—Chemical Arithmetic—Bases—Quantivalence—Tests—Table of Chemical Elements—-Chemistry of Familiar Things—Common Names of Chemicals—Radio-Activity and Radio-Active Substances—Radium and its Uses—The Spinthariscope
Importance of Chemistry
A certain amount of knowledge of chemistry is eminently useful in almost every walk of life. An intelligent knowledge of the chemistry involved in the processes of the kitchen, the dairy, the dye-house, the farm, or the manufactory, places the possessor engaged in any of these processes on a different level from the rule-of-thumb worker, who is as ignorant of the reason for adopting a particular method as he is of the properties of the materials he employs.
Technical chemistry deals especially with the application of the principles and processes of chemistry to the arts and manufactures, and it is to those who are engaged in manufactures of almost every kind that a knowledge of chemistry is a particular advantage.
It is not a question of expediency alone, but one of absolute necessity that a technical education, including chemistry as one of its principal subjects, should form not the least important part of the equipment for his work of any artisan who is to excel in his employment in intelligence and skill.
What is chemistry?
Chemistry is that branch of science which treats of the intimate composition of matter, and the changes produced in it when subjected to particular conditions—such as temperature, pressure, mass, light, catalysis, etc.
How does chemistry differ from physics?
The two branches, physics and chemistry, overlap a great deal, it being very difficult to draw the line of demarcation between them, particularly in the higher stages of the physical and chemical changes of matter.
For example, a steel needle rubbed on a magnet in a definite way undergoes physical change by means of which it acquires the power of the magnet. On the other hand, a match rubbed on a match-box undergoes a chemical change by means of which flame is produced. Thus it is possible to make a distinction between the sciences of physics and chemistry. A chemical change involves some alteration in the essential nature of the substance. The match having been ignited has undergone a permanent change, whereby it is no longer combustible. The physical change quoted above involves no alteration in the substance itself, and the acquired property is further only temporary and can be continually lost and reacquired.