only a separation, but a new combination. There is a force by which the particles of the solvent associate to themselves the parts dissolved, not a force by which they repel and dissever them. We are here to imagine not mechanical action, not violent impulse, not antipathy, but love, at least if love be the desire of uniting. (Non igitur hic etiam actiones mechanicæ, non propulsiones violentæ, non inimicitiæ cogitandæ, sed amicitiæ, si amor dicendus copulæ cupido.) The novelty of this view is evidenced by the mode in which he apologizes for introducing it. 'Fateor, paradoxa hæc assertio.' To Boerhaave, therefore, (especially considering his great influence as a teacher of chemistry,) we may {17} assign the merit of first diffusing a proper view of Chemical Affinity as a peculiar force, the origin of almost all chemical changes and operations. [Note 13\6: _Elementa Chemiæ_, Lugd. Bat. 1732, p. 677.] 3. To Boerhaave is usually assigned also the credit of introducing the _word_ 'Affinity' among chemists; but I do not find that the word is often used by him in this sense; perhaps not at all[14\6]. But however this may be, the term is, on many accounts, well worthy to be preserved, as I shall endeavour to show. Other terms were used in the same sense during the early part of the eighteenth century. Thus when Geoffroy, in 1718, laid before the Academy of Paris his Tables of Affinities, which perhaps did more than any other event to fix the Idea of Affinity, he termed them 'Tables of the Relations of Bodies;' '_Tables des Rapports_:' speaking however, also, of their 'disposition to unite,' and using other phrases of the same import. [Note 14\6: See Dumas, _Leçons de Phil. Chim._ p. 364. Rees' _Cyclopædia_, Art. Chemistry. In the passage of Boerhaave to which I refer above, _affinitas_ is rather opposed to, than identified with, chemical combination. When, he says, the parts of the body to be dissolved are dissevered by the solvent, why do they remain united to the particles of the solvent, and why do not rather both the particles of the solvent and of the dissolved body collect into homogeneous bodies by their _affinity_? 'denuo se affinitate suæ naturæ colligant in corpora homogenea?' And the answer is, because they possess another force which counteracts this affinity of homogeneous particles, and makes compounds of different elements. Affinity, in chemistry, now means the tendency of _different_ kinds of matter to unite: but it appears, as I have said, to have acquired this sense since Boerhaave's time.]