ticularly those of volumetric analysis. The ideas involved in the solution of proportions are so labored and so unnecessary and require such cumbersome solutions of problems involving them that it is difficult to see why emphasis has so generally been placed upon this rule in chemical calculations. Other teachers will, no doubt, differ with the author upon this point. It is desired only that the method of presentation involved in these pages be tested, not in part but in whole, before final judgment is given. Most of the calculations involved in the laboratory exercises have been left to the student. Principles of such calculations are first fully explained but ready-made calculations that leave nothing to the ingenuity of the student furnish poor preparation for scientific analysts. Acknowledgment is here gladly expressed to Mr. H. C. Mahin for all of the original drawings in this book, also to Wm. Ainsworth and Sons, Bausch and Lomb Optical Company, the Bureau of Standards, Eimer and Amend and The Scientific Materials Company for several cuts which they have loaned. LAFAYETTE, IND., EDWARD G. MAHIN. General operations-Preparation of samples-Solution-Precipita- EXPERIMENTAL GRAVIMETRIC ANALYSIS. Calcium Silver and the halogens-Aluminium-Barium and sluphuric acid-Strontium-Potassium and sodium-Recovery of platinum from waste-Magnesium and phosphoric acid-Man- ganese-Chlorine, bromine and iodine-Carbonic acid and carbon Nature of electrolyte-Solvent-Temperature-Electrolytic pres- sure Current density-Nature of electrodes—Other apparatus— PAGE Apparatus-Units of volume-Calibration by weighing-Calibra- tion by standardized bulbs-Calculation of the results of volu- metric analysis-Calculation of the weight of one substance chem- ically equivalent to a stated weight of another-Use of a standard solution for the titration of but one substance-Burette reading a Simple ionization theory-Theory of chromophors-Theory of absorption by electronic vibration-Classification of organic Direct weighing-Weighing a substance produced by a measured volume of solution-Measuring the volume of solution required to react with a known weight of a substance of known purity- Titration against another standard solution-Primary standards. EXPERIMENTAL VOLUMETRIC ANALYSIS Standard acids-Materials for standardization-Standardization by direct weighing-Preparation of pure sodium carbonate-Soda ash-Mixtures of carbonates and bases-Mixtures of carbonates Potassium permanganate-Iron-Reduction of iron solutions- Calcium-Manganese-Available oxygen-Potassium dichromate Iron-Chromium-Iodine and sodium thiosulphate-Oxidizing power of peroxides-Copper-Bleaching powder-Arsenical insec- ANALYSIS OF INDUSTRIAL PRODUCTS AND RAW MATERIALS. Carbonate minerals-Silicate minerals-Coal and coke-Prox- imate analysis-Ultimate analysis-Fuel value-Gas mixtures— Burning oils-Lubricating oils-Edible fats and oils-Water for industrial uses— -Water for sanitary uses- INTRODUCTION In the study of such divisions of chemistry as naturally precede quantitative analysis the work has been mainly descriptive. The chemical and physical properties of elements and compounds have been determined. Laws of chemical action have been developed and theories have been evolved for the explanation of such action and as generalizations upon which to plan further studies and investigations. In the courses in qualitative analysis an effort was made to detect and recognize elements and their compounds by certain characteristic reactions of these substances and to separate more or less complicated mixtures into their constituents. Quantitative analysis is the next logical step in the study of the composition of matter. The qualitative analysis should precede the quantitative, unless the nature of the substance is already known, because in nearly all cases the presence of substances other than those whose percent is being determined will make necessary certain modifications in the method to be employed. Whether or not a qualitative analysis is made it is a fact to be constantly kept in mind that an intelligent understanding of quantitative processes can be obtained only by a continued. application of the facts and laws earlier learned to the newer processes which are being studied. The industrial development of the world, as well as the evolution of chemistry as a science, would be a more rapid and substantial change were it not for the numbers of inadequately trained chemists who have found a place in industrial work and who have been content to allow their study to go no farther than the routine of following directions without understanding. This is the inevitable end of the student who does not begin his scientific study with the definite determination to patiently and persistently think out each problem to its logical conclusion as it presents itself, and who does not continue this process in his work in quantitative analysis, reviewing his earlier work until the principles that were imperfectly understood expand and illuminate the newer problems. |