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which enter into neutrality with an equal amount of vitriolic or muriatic acid, are the three first terms of two series, of which, that which belongs to muriatic acid proceeds by the odd numbers without interruption, and the other is the product of a quantity with the numbers in regular succession."

Page 167. "When an aqueous solution of vitriolic salammoniac is poured into a solution of muriate of lime, an abundant precipitate is caused, which is completely formed gypsum; if the exact quantity of the salammoniac solution has been used which is necessary to complete the precipitation, the liquid above the precipitate contains nothing but perfectly formed common salammoniac. But the proportion in the salt is 1000 1107, and to 1000 of the chloride are to be calculated 889 parts of the volatile alkali; now let us inquire how much of the vitriol is needed for 1107 parts of the lime, the proportion of the last to the first is 796: 1000, consequently 1107 parts of lime demand 1009.1107=2215000=1394 parts of vitriol, which belong to the 889 parts of the volatile alkali. He gives a list, page 279, of "Proportional quantities of neutral compounds which decompose each other, when entirely deprived of water." "In each of these cases it is only necessary to add the numbers representing the quantities standing against each other horizontally, by which the power of the affinity is estimated, and we receive the neutral quantities which decompose each other, and consequently their proportion."

Salammoniac Vitriol.

689 + 1000

Salammoniac Vitriol.

638 + 1000

Magnesia Salt.

* * * *

[blocks in formation]

858 + 1000

:

22391394 1858: 3633

&c., &c., &c.; this is from a list of 28: the second and third

are supposed hydrous.

Then we have, p. 284, "Proportional quantities of neutral compounds containing muriatic acid, considered as anhydrous, when decomposed by vitriolic acid." Also, "Proportional quantities, when the neutral compounds which vitriolic acid makes with the alkaline salts and magnesia are decomposed negatively or by free muriatic acid." P. 293. At page 190, he says, that the affinities are as the amount of the combining proportions, and here also the atomic weights of ammonia, soda, and potash, are such as to lend some countenance to it. The series, however, is still considered the most important thing, and he finds afterwards, in the vol. for 1800, that smaller weights may precipitate larger ones.

These inquiries were continued with great labour, and in his work "On the newer subjects in chemistry," we have many attempts to define the relations between the acids and bases. In the vol. for 1798, we find him fixing the relation between the metals and some of the acids, but always on the same plan.

At page xv. in the preface to the vol. for 1800, he says, "To follow an author step by step, in a path trodden by him alone, and to judge him with fairness, is not in the power of every one, still less can it be done by merely reading through his book."

Page xxiii. Again, "Whoever looks on the remarkable order, which reigns in the quantitative proportions, by which every kind of substance has a peculiar quantitative character with respect to another, as a mere play of figures, or as a mere accident, would only show his complete ignorance of the whole structure of stœchiometry, but would be indemnified for it by a still greater degree of philosophical faith; for it requires much more credulity to believe in so many accidents, than is needed to perceive that the Lord of nature has not only qualitatively but quantitatively endued it with the most wonderful order, both in great things and in small.”

Another extract from the same, page 206, "In the simpler

affinities every kind of neutralizable substance has its own quantitative law of affinity, because the amount of affinities among the alkalies may be expressed by the mass, that of the acids by the substratum (that is, the body of which the oxygen of the acid is an oxide); but this is not found to be the case either with the metallic or nonmetallic combustible elements."

This

What then did Richter attain to is the question to be now answered. In the extract from the preface he raises the study of atomic chemistry to a science, and gives it a name. is itself no small honour. The chemists before him had certainly not been gifted with such a clear appreciation of the importance of the study. We find that Richter has made it the leading object of his life to elucidate the laws of combination; as a young beginner, making it a subject of his inaugural dissertation, and looking forward to the time when he might have opportunity to prosecute his investigations. The word stœchiometry is preserved in Germany, with us it is too abstract for daily use.

The first definition of stœchiometry has appended to it six experiences (erfahrung), most of them with corollaries (zusatz). The reading becomes, therefore, exceedingly cumbrous, the words are marvellously multiplied, pure abstraction is aimed at in every step with painful strains, as it would appear, or perhaps only caused by a mathematical habit of mind too exclusively followed. In this way the few truths that we still hold to, and which are contained in the book, are so ornamented and overdressed as to have been to most persons entirely hidden under the richness of the elaboration.

He expresses his belief that the smallest portions of a body are of the same composition as the largest. He says that the affinity exists in every particle. Then adds that every piece must have the same composition. His own words are very cumbrous, but this meaning is distinctly there. This was the illustration which Dalton afterwards used on the same

subject, but it was expressed in clearer words, and still earlier, by Higgins. This idea leads directly to the atomic theory and theory of equivalents. Here it is not followed out.

The sixth experience of first definition gives the theory of reciprocal saturation, when double decomposition takes place in solutions. This is the discovery which has been attributed to Wenzel. Let us translate his formulas into the present symbols by an example :

Ago No-N05, N05+K0 S03—S03, S03

Nog+KO SO2—S03+S03+Ag0 N05-N05.

He says the products of neutral salts are nearly without exception neutral, but nevertheless sees enough to form a law. Wenzel, with similar results, had not seen a law.

He endeavours to shew the relative amount of force exerted by different substances when decomposition takes place, but he gets no farther than the fact that certain forces are equal, some must be greater, and others must be less. In this district of inquiry, an example of which may be found in Theorem I., what appears to be the enunciation of an important law, frequently turns out to be the mere expression of a common-place, giving no information to the chemist. Such laws being in a certain sense universal, they are now left out of chemical works, as the mind can readily draw the conclusion for itself, if the opportunity offers.

He then shews the method of obtaining the proportion of the elements in a compound. This had been pursued with great care by Wenzel.

The great aim of Richter is not perceived in reciprocal proportion, but in the attempt to make the combining numbers of all bodies a series in arithmetical progression, and so to bring number, quantity, and order into the arrangement of the elements. In the series which he has formed, I think we may say that he has failed to prove his point. The numbers he had were too few, and the mode of obtaining the order is by no means satisfactory. There is, however, a

great probability recognised by most chemists of the existence of an order in which the elements are related to each other. If this order should ever be found to be similar to that which Richter has indicated, we must do the greatest honour to his genius, although we cannot even now, when it stands before us, say that it is a discovery, or that it has any value at all.

The discovery of reciprocal proportion is given by no one before Richter as far as I know, but he himself does not speak of it as a discovery, but as a well-known fact, with which he was familiar before he wrote his inaugural dissertation. We find in the preface that it was well known that neutral salts gave neutral results on decomposition; this Richter has put formally amongst the laws of stoechiometry, and given it rank amongst chemical truths. He deduced from it, as he himself says, that there must be "distinct proportionate quantities amongst the component parts of neutral salts," and he strove hard to bring all combinations under number and quantity. The knowledge of this fact seems to have first set in motion his stoechiometry; instead then of being the point which he gained, it is the point from which he starts, according to his own account. He does not, however, seem to have seen the reason for it, nor its general bearing in chemistry, otherwise it could not have been left for Fischer to shew that the combining number of an element would fit its combination with every other element.

The mode in which he obtains the relation of the combining weights of the earths to each other is remarkably selfdelusive, but at the same time exceedingly ingenious. They are given at length, so that every one may compare for himself.

He endeavours to find out a similar relation between the atomic weights of the alkalies, and readily does so. He is led away by the numbers observed to mistake them for representations of actual force, and so calculates in a relative and abstract way the force needed for decomposition. This is

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