Cambridge, Massachusetts, United States
Leipzig, Saxony, Germany
University of Leipzig
Ithaca, New York, United States
(This book was originally published prior to 1923, and rep...)
This book was originally published prior to 1923, and represents a reproduction of an important historical work, maintaining the same format as the original work.
(This work has been selected by scholars as being cultural...)
This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact, and remains as true to the original work as possible.
(The two expressions describing in a qualitative manner al...)
The two expressions describing in a qualitative manner all states and changes of equilibrium are the Phase Rule and the Theorem of Le Chatelier. A phase is defined as a mass chemically and physically homogeneous or as a mass of uniform concentration, the number of phases in a system being the number of different homogeneous masses or the number of masses of different concentration. In the case of water in equilibrium with its own vapor there is the liquid and the vapor phase, two in number. If there is a salt dissolved in the water there are still two phases, the liquid or solution phase and the vapor phase. If ice crystallizes, there is added a solid phase and the number becomes three. If, in addition, the dissolved substance separates in the solid form or as a second liquid layer, there will be four phases present, the vapor, liquid and two solid phases or the vapor, solid and two liquid phases as the case may be. Although the ice separates in many crystals, yet each is like every other in composition and density and taken together they constitute one phase. If the crystals were not alike as is the case with rhombic and monoclinic sulfur they would form as many phases as there were kinds of crystals, two in the example just cited, three if we have diamond, graphite and carbon. The components of a phase or system are defined as the substances of independently variable concentration in the phase or system under consideration. A component need not be a chemical compound, that is a substance described by the Theorem of Definite and Multiple Proportions, though this is usually the case. For instance, a mixture of propyl alcohol and water in such proportions that the percentage composition of the liquid is the same as that of the vapor might be treated as one component; but there is no advantage in this, as it is true for only one temperature and when there are no other components. The main point to be observed in determining the number of components in a given system is that each compound is not necessarily a component. Thus a hydrated salt is to be treated, when in equilibrium with the solution or vapor, as made up of salt and water and is not in itself a component. The same holds true of a double salt such as the double sulfates of copper and potassium. Here the components are the two single salts and water because the concentration of these three can be varied and they are sufficient to form all modifications which can exist. If one is treating calcium carbonate in equilibrium with calcium oxide and carbonic acid, there are only two components, calcium oxide and carbonic acid; for the calcium carbonate is merely a solid phase containing the two components. The fact that the two components unite to form a phase in definite proportions does not have anything to do with the matter. On the other hand it is not permissible to take calcium and oxygen as two of the actual components of this system because they are neither independent variables nor are they in equilibrium with the system....
Bancroft received a Bachelor of Arts degree from Harvard University in 1888. Four years later he earned his Doctor of Philosophy degree from the University of Leipzig.
Wilder was given an honorary Doctor of Science degree from Lafayette College in 1919 and Cambridge University in 1923.
Bancroft began his career as an assistant chemistry instructor at Harvard University in 1888 and held it for a year and again in 1893-1894. Then in 1894, he took a position of an instructor at the same university.
In 1895, Wilder was appointed an assistant professor of physical chemistry at Cornell University. Eight years later he became a professor and was named World War Memorial Professor of Physical Chemistry in 1919 at that university, where he served until his retirement in 1937 as a professor emeritus.
Also in 1896, Bancroft founded Journal of Physical Chemistry and became its editor, where he worked until 1932. In addition, in 1913, he held a position of an associate editor of Journal of Franklin Institute.
(This book was originally published prior to 1923, and rep...)2012
(The two expressions describing in a qualitative manner al...)2017
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(This book was digitized and reprinted from the collection...)1921
Bancroft was a member of American Academy of Arts and Sciences, American Electrochemical Society (president 1905, 1919), American Electroplaters Society, American Chemical Society (president, 1910), American Physical Society, National Academy of Science and American Philosophical Society.
Bancroft was a brilliant theorist and a forceful exponent of new ideas arising from the application of physico-chemical concepts to chemical problems.
On June 19, 1895 Wilder Bancroft married Katharine Meech (Bott) Bancroft. They had five children.