[Note 18\6: _Progr._ I. II. _de Affinitate Corporum Chimica_. Jen. 1775, 1776.] Nevertheless, in 1775, the Swedish chemist Bergman, pursuing still further this subject of Chemical Affinities, and the expression of them by means of Tables, returned again to the old Newtonian term; and designated the disposition of a body to combine with one rather than another of two others as _Elective Attraction_. And as his work on _Elective Attractions_ had great circulation and great influence, this phrase has obtained a footing by the side of _Affinity_, and both one and the other are now in common use among chemists. 4. I have said above that the term _Affinity_ is worthy of being retained as a technical term. If we use the word _attraction_ in this case, we identify or compare chemical with mechanical attraction; from which identification and comparison, as I have already remarked, no one has yet been able to extract the means of expressing any single scientific truth. If such an identification or comparison be not intended, the use of the same word in two different senses can only lead to confusion; and the proper course, recommended by all the best analogies of scientific history, is to adopt a peculiar term for that peculiar relation on which chemical composition depends. The word _Affinity_, even if it were not rigorously proper according to its common meaning, still, being simple, familiar, and well established in this very usage, is much to be preferred before any other. But further, there are some analogies drawn from the common meaning of this word, which appear to recommend it as suitable for the office which it has to discharge. For common mechanical attractions and {20} repulsions, the forces by which one body considered as a _whole_ acts upon another external to it, are, as we have said, to be distinguished from those more intimate ties by which the _parts_ of each body are held together. Now this difference is implied, if we compare the former relations, the attractions and repulsions, to alliances and wars between States, and the latter, the internal union of particles, to those bonds of affinity which connect the citizens of the same state with one another, and especially to the ties of Family. We have seen that Boerhaave compares the union of two elements of a compound to their marriage; 'we must allow,' says an eminent chemist of our own time[19\6], 'that there is some truth in this poetical comparison.' It contains this truth,--that the two become one to most intents and purposes, and that the Unit thus formed (the Family) is not a mere juxtaposition of the component parts. And thus the Idea of Affinity as the peculiar principle of chemical composition, is established among chemists, and designated by a familiar and appropriate name. [Note 19\6: Dumas, _Leçons de Phil. Chim._ p. 363.]