Chemistry is 1 concerned with what things are made of and how various substances react with each other. One of the chemist's most important 2 is to find out as much as possible about the nature of matter. By 3 we mean something which occupies spare and has mass. If you are a chemistry student, you will begin to learn something of the way 4 which a chemist works: how he experiments, records and deduces; how he 5 out a theory and then tries to prove it by producing as much evidence as possible in 6 favor, but is always ready to abandon one theory for another if he finds that it 7 the facts more closely. You may sometimes think as you read on that you have picked up a history book by mistake, but it is important for you to know 8 the knowledge of certain 9 of the subject has grown and developed, for in chemistry, as in other branches of knowledge, men advance by climbing on to the shoulders of their 10 Much important work has been done in the past, but during this century the pace of research and 11 has accelerated at a phenomenal rate. These are exciting 12 for the scientist, and future generations of workers in the field of chemistry will find that there is much to be learnt and many new fields of 13 to choose from. Some time in the future, you may use the knowledge and experience of some 14 present- day chemists to help you in a new branch of research, and you will perhaps have cause to be 15 for the work of those scientists who have gone before you.