M. J. B. Richter, another German chemist, remark able no less tor the zeal with which he investigated che mical proportions, than fear the mathematical form, which in his work on chemical stochiometry he wished to im press on the general face of chemistry—occupied himself with these researches inure than any of his predecessors. Great part of his ideas being erroneous, we shall not speak of them. But he not only confirmed, by experiments, the idea of Bergman, and that of Wenzel, he also gave to theert a wider extension. His experiments are described in a periodical work, which he published under the title of Uber die nruen Gegenstande der Chemie ; and it was prin cipally in Numbers 7, 8, and 9 of this work, that he de veloped the matters in question. Yet the labours of Richter were not more successful in attracting notice ; a circum stance that may he attributed asmuch to the inaccuracy of his experiments, in which respect he cannot be compared with Wenzel, as to his peculiar style, which affects to hold a mid dle course between the antiphlogistic and the phlogistic system. It is not, however, very probable that those germs of discovery would have been lost solely for such a reason, which at all events applies only to Richter. The cause of this neglect is more general. These researches were com pleted precisely at the time when the immortal Lavoisier, by discoveries of his own, and by luminous applications of the discoveries of others, was undermining the phlogis tic system, dazzling chemists by the new light which he prepared for them, and rendering his own system the sole object of their attention. That system presented objects . of research, which at the moment promised to become of an importance vastly greater and more general. In vain did Richter publish his mathematico-chemical specula tions; no one listened to him. By degrees, however, the system of Lavoisier was consolidated ; finally adopted by its most stubborn opponents, it became generally known ; and the greater part of our present chemists have studied the science under no other form but that which Lavoisier's hypothesis presents. The attention which, during five and twenty years, had been directed to this single point, was at length divided; and the luminous rays disseminated in the works of hostile or prior writers beamed forth anew. It may thus be affirmed, that the birth and consolidation of the antiphlogistic system put a stop, for a time, to the in vestigation of chemical proportions, which originated at the same period.
Lavoisicr himself advanced nothing very decided upon this point. He observed that there is one species of com bination always limited to fixed proportions, and another which may take place in variable proportions; and he thought that being of a different nature, they ought to be carefully distinguished. He proposed to give them differ ent names ; he called the first dissolution, the second so lotion. A combination of the oxyd of iron, with sulphu ric acid, is an example of dissolution ; hut when the sul phate of iron is melted by water it forms a solution.
Some time after the death of Lavoisier, \I. Berthollet, the most distinguished of his fellow-labourers, published a work under the title of Essai de Statique Chimique, in which he considered affinities, and the phenomena that de pend on them, with a truly philosophic eye, and to the admiration of all chemists. He endeavoured to prove that the active forces are not so multifarious as the diversity of the phenomena might lead us to suppose ; and he made it probable that chemical affinities depend entirely upon a single force ; just as the force which causes a body to fall towards the earth is the same as that which retains the planets in their orbits. In a word, he conjectured that one
day we should be enabled to calculate the former as accu rately as, from a distant period, we have calculated the phenomena dependent on the other.
Berthollet, proceeding farther, attempts to prove that solutions depend on exactly the same affinity as dissolu tions; the difference consisting merely in the degree of energy possessed by this affinity, which is smaller in the former case than in the latter. Elements, he maintained, have a minimum and a maximum, beyond which they can not enter into combination; but between these two points they unite in every proportion, no other limit to their union being fixed. Whenever they happen to combine in fixed proportions between those two points, their union is due to other circumstances; for most part to cohesion, which renders the combination insoluble; or to expansion, which renders it gasiform. If in combining they undergo a high degree of condensation, the proportions in which they unite are always invariable; and for this reason gaseous substances never combine except in fixed proportions : hy drogen with oxygen, for example; azote with oxygen, and so on. But when, after combination, the elements con tinue in the same degree of density as before it, they may unite in all proportions between the maximum and the mi nimum. The regularity of proportion subsisting among the elements of acids, salts, Ste. depends, according to this theory, on nothing but the condensation of the gaseous form, or on crystallization. Berthollet made a multitude of experiments to prove the truth of these ideas ; and though it is now believed that his opinions are not well founded, he must be allowed to have expressed them, as well as their proofs, with a sagacity and philosophic dis tinctness at once convincing and uncommon. He examin ed the experiments of Richter, and found numbers differ ont from his. He first disputed, but afterwards admitted, the mutual relation among bases observed already by 1Venzel, though he attributed it to cohesive force, in other words, to crystallization.
A philosophical chemist requires to be seconded by the talent of wisely choosing his experiments, and of execut ing them with address; otherwise, perpetually deceived by them, he will build upon false foundations. So it has hap pened to this illustrious chemist. His experiments, viewed as exact analyses, have always given results extremely in accurate, so that scarcely one of them is just ; and in this point of view Berthollet h.as been still less lortunate than TYWri T1. r Richter. observed, and proved indisputably, that elementary particles act not only according to the de gree of their affinity, but also according to their mass. This phenomenon, however, does not happen except when the bodies that act, as well as the products of their mutual action, all continue mixed in solution, or under a liquid form. As Berthollet admits no other difference between solution and chemical combination but the degree of af finity, it seems probable that his mistake with regard to this point has occasioned all the rest.