NOTE ON THE PERIODIC MODIFICATION OF ELECTRO-STATIC INDUCTION. By Prof. H. S. CARHART, N. W. University, Evanston, Ill. ON THE SENSITIVENESS OF THE EYE TO COLORS OF A LOW DEGREE OF SATURATION. By Prof. E. L. NICHOLS, University of Kansas, Lawrence, Kansas. A SPECTROPHOTOMETRIC STUDY OF PIGMENTS. By Prof. E. L. NICHOLS, University of Kansas, Lawrence, Kansas. FIRST STEPS TOWARD A GENERAL SYSTEM OF OBSERVATIONS OF ATMOSPHERIC ELECTRICITY. By Prof. CLEVELAND ABBE, Washington, D. C. ORGANIZATION OF SEISMOLOGICAL OBSERVATIONS. By Prof. CLEVELAND ABBE, Washington, D. C. METHODS OF VERIFYING WEATHER PROBABILITIES. By Prof. STANDARDS OF BAROMETRY AND THERMOMETRY. By Prof. ON THE ROTATION OF THE EQUIPOTENTIAL LINES OF AN ELECTRIC CURRENT BY MAGNETIC ACTION.1 By Dr. E. H. HALL, In structor in physics at Harvard College, Cambridge, Mass. 'Printed in full in the American Journal of Sciences, Vol. XXIX, Feb., 1885. ADDRESS BY PROFESSOR JOHN W. LANGLEY, VICE PRESIDENT, SECTION C. FELLOW MEMBERS OF THE CHEMICAL SECTION: LADIES AND GENTLEMEN: IN reviewing the history of each living being and of every intellectual conception, we are at once made aware of a law of growth the most general and fundamental possible, namely, that of development, or progression along what often seems to be a predetermined line whose constraining influence is so powerful that it is only by following it that the organism can escape destruction. Development, while it may be continuous, both for the individual and for the race when broadly looked at over large intervals of time, is, on the other hand, a process which, in its details, is constantly interrupted both by alterations of direction and by arrests of action which may even go so far as to cause retrograde metamorphoses. A plant may readily grow unsymmetrically if shaded on one side; but that error of form will be largely corrected when it is again bathed with light which comes from all directions. This partial arrest may even arise from the plant itself, as when the excessive growth of the vine in forming new wood saps the energy which should go to the formation of fruit, and the grapes, which alone make the plant valuable to man, never reach that fullness and flavor which should recompense the toil of the husbandman. All of us here are constituent intellectual atoms in a great ideal organism called Chemistry. We know the long and honorable history of our science; we know, too, its wonderful progress in the past fifty years; we perceive how from the single stem of Alchemy it has thrown out branches in all directions, mineral, organic, analytical, synthetic, agricultural, physiological, biological chemistries; but has it furnished a corresponding number of great farreaching laws? Has it been equally prolific of grand hypotheses which have stood the test of time? Will you pardon me if I venture to apply the analogy of the plant, and to ask whether our development has been symmetrical, whether some struggling bud put forth in our youth has not been starved and shaded by the abundant leafage of our branches, and whether in the rapid accumulation of facts from that great diffused solution of them called Nature, while we may have greatly increased our quantities of chlorophyll and cellulose, we have equally gained in the fruit, whether we have been equally successful in elaborating well-rounded generalizations which fill the intellectual taste with a sense of delight, and which stand forth as the declared fruit of our toil. Such a bud our science put forth in its alchemical stage under the name of affinity. During the early part of the present century the idea received considerable expansion and showed, at one time, a vitality comparable with the condition of the doctrine of the conservation of energy prior to the year 1850. Having reached this stage the development of a theory of affinity seems to have been arrested and soon it is seen occupying a position of constantly decreasing interest to chemists. The proof of this statement is easily found by comparing such works as Daniel's Introduction to Chemical Philosophy, Thompson's History of Chemistry and Daubeny's Atomic Theory, published in 1830 and '31, or the works of Berzelius, with any recent manual of inorganic chemistry. In the older books the amount of space given to the treatment of chemical affinity is relatively large, while in the treatises of to-day it is in many cases hardly even mentioned. In the article Chemistry in the new Encyclopædia Britannica, covering 120 pages, there is not a single paragraph referred to the title affinity, and less than half a page devoted to it indirectly. In Watts' Dictionary of Chemistry, including the supplements, out of a total of 9665 pages, only 62 are devoted to affinity where it appears under the head of chemical action. In Wurtz's Dictionnaire de Chimie, the treatment of affinity under the several heads of chaleur, electro chimie, affinité, atomicité, etc., is relatively fuller, but still the proportion is quite small, and in that excellent manual Remsen's Theoretical Chemistry, the second edition of |