Chemical Control of Cane Sugar Factories. By William D. Horne.... 128 North American Index Fossils. By Amadeus W. Grabau and Hervey FIRST LECTURE. ELEMENTS AND COMPOUNDS. Ladies and Gentlemen: The task I have undertaken for to-day and the following days is to give you a sketch of the scientific development of chemistry, and of the history of the leading ideas in their broadest generalization. Chemistry is a very large science indeed. You remember possibly one or two years ago there was celebrated the day of the coming into existence of the 50,000th compound in organic chemistry; this shows at once how large chemistry is, for besides these 50,000 compounds of organic chemistry there are the inorganic compounds which have not been counted as yet. To get a comprehensive view of such a vast body we will make use of a method which is in vogue with biologists, to investigate complicated organisms. It is known as the cross-section method. This method consists in cutting through the organisms parallel cross-sections from side to side, and investigating and comparing them; by such comparison of these different cross-sections they get a comprehensive view of the whole organisms. In this * Course of six lectures delivered in the Department of Chemistry of Columbia University, in Havemeyer Hall, January 26 to February 2, 1906. Reported stenographically. Copyrighted by SCHOOL OF MINES QUARTERLY. 87 way we are going to cut different cross-sections through the whole body of chemistry. In every case we will investigate the development of a certain set of ideas and changes from the first beginnings which we know of, down to their latest development in our times, and in this way I hope to present to you some plastic views of the whole science of general chemistry. As to the first cross-section: We shall investigate to-day what lies at the very bottom of every chemical investigation.—It is the question of the chemical elements; the difference between elements and compounds. This is the framework in which every chemical fact finds later its place in properly arranged sequence. Now the first stages of every development always seem to us rather absurd. It is the same with the question of chemical elements. The peripatetical elements, as they have been called and as they have been maintained through many centuries, were first invented by Aristotle. Aristotle after examining the possible properties of different bodies and their changes, reached the idea that every body should be possessed of at least one of the following properties: It should be either dry or wet; and it should be either warm or cold. Why Aristotle selected just these properties it is impossible to tell now. They probably seemed the best to his systematic mind, and so he arranged the following scheme: Although these four things can be combined in six different ways, but two of these possible combinations will not do, because a body can not be at the same time wet and dry, or hot and cold, and therefore only four combinations remain between wet and cold, and cold and dry, and dry and hot, and wet and hot. These are the four elements of Aristotle. Something which is cold and wet is comparable to water, and therefore water is one element. A thing which is wet and hot is comparable to air, and therefore air is another element; and something which is dry and hot at the same time would be fire; and something which is cold and dry at the same time is earth. Now we have here the four ancient elements, and these elements were considered as the true elements of every kind of matter through a long series of years. This may have been satisfactory to a philosophical mind, but it did not prove satisfactory to the chemists who were busy investigating the different substances and the possibilities of their changes. Chemistry has developed, as every science has, from practical questions; from the questions of dye manufacturing, metal manufacturing, the manufacturing of chemical compounds, etc., and slowly all this scattered knowledge was brought into order and arranged to constitute the science of chemistry. Now, this knowledge of chemical changes and chemical preparations did not fit very well into the beautiful scheme of Aristotle's, and therefore the chemists tried to discover some system which would fit better with their practical experience. They found that the different substances could be arranged in certain classes in such a way that every body could be put into one of these classes, and as types or heads of these classes they selected, first, sulphur, to explain or describe the possibility of burning or combustibility; then they made the class of mercury to describe the metallic properties; then the class of salts, for substances which are soluble in water and have a distinct effect on the taste; and at last there were substances which did not possess any of these properties which did not affect the taste, were not soluble in water, did not show a metallic lustre and were not combustible. These substances were put into the class of earths, therefore earth was the only class which remained from the old Aristotle scheme. You see at once that this distinction or classification was much more practical than that of the old philosopher, but it was still rather imperfect. It is a most general fact in the psychology of science that even if an old and habitual view proves to be quite erroneous, the correction of such a view is never an absolute or radical one. People try rather to correct only in a somewhat superficial way the worst part of the old view, to retain as much as possible of it. Therefore there remains in every case, even after a practical correction, some absurdity from the older view in the newer one, or some unjustifiable assumption. And so it was also with these elements of sulphur, metals, earths and salts. For they assumed tacitly the same thing that Aristotle has assumed in making his definitions, that matter was in truth something inert and devoid of properties and that this inert matter could be endowed with different properties at will. They assumed that these properties could be taken away from one piece of matter and given to another piece of matter; in fact the general view of |