tailieunhanh - Bài giảng Biến đổi khí hậu

Of tlie stndy of elementary chemistry in schools is to educate the mind by giving it the right kind of exercise in tlie use of its powers, I have therefore tried to make a, judicious selection of the most fundamental facts and principles of chemistry, and to present these in such a way tliat the student must constantly use his senses to discover facts, his reason in drawing correct inferences from the data he collects, and good English in expressing accurately what he sees and thinks. | PREFACE. Ik an Elementary Chemistry written iu 1873 it was my purpose to give a short course for beginners in which the experimental evidence on which the most fundamental parts of the science rested should take the place of minute details and advanced theoretical discussions hoping in this way to encourage the study of chemistry by experiment instead of bybooks alone as was so much the custom at that day. A Student s Guide printed for the use of my classes in 1878 contained a course introductory to qualitative analysis giving the student nothing blit an outline of experiments. He was expected to make the experiments to observe and describe Ills own results and from these to construct for himself a plan for the detection of the metals. 1 now combine the leading ideas of those two books and offer to my follow-teachers a new volume in which they lire more fully developed in ways suggested by the unbroken experience of the intervening years. Chemistry as a branch of study in the schools has two great merits happily combined. One is tô be found in the kind of knowledge it offer s and the other in the peculiar mental training it affords. Of these the latter is certainly not the least important because a person is well educated not so much in proportion to what he knows as ill proportion to what he Ciin do with his knowledge. Hence a chief purpose ill iv PREFACE. of the study of elementary chemistry in schools is to educate the mind by giving it the right kind of exercise hl the use of its powers. I have therefore tried to make a judicious selection of the most fundamental facts and principles of chemistry and to present these in such a way that the student must constantly use his senses to discover facts his reason in drawing correct inferences from the data he collects and good English in expressing accurately what he sees and thinks. I know of but one way to teach a student howto acquire a real knowledge of nature and that is to fix his mind habitually on things and .