'When we reflect," says Mr. Weld, "on the benefits conferred on mankind by the discoveries of modern science, Englishmen must feel an honest pride in the fact that so large a proportion have emanated from the Fellows of the Royal Society. Nor will that pride be diminished, when it is remembered that from first to last the Society has received no annual pecuniary support from government, nor assistance of any kind, beyond the grant of Chelsea College, shortly after their incorporation, and more recently, the use of the apartments they now occupy in Somerset House.* While the members of the French Institute receive a yearly stipend, the Fellows of the Royal Society pay an annual sum for the support of their institution and the advancement of science. It would be repugnant to the feelings of Englishmen to submit to the regulations of the Institute, which require official addresses, and the names of candidates for admission into their body, to be approved by government before the first are delivered or the second elected. The French savans are, it is true, ennobled and decorated by orders, which the wiser among them, in common with true philosophers of any country, regard with indifference. Nobly did Fourier say of Laplace: "Posterity, which has so many particulars to forget, will little care whether Laplace was for a short time minister of a great state. The eternal truths which he has discovered, the immutable laws of the stability of the world, are of importance, and not the rank which he occupied."

As a consequence of this independence and self-support, it was necessary that the Royal Society should be numerous, and by a consequence not less necessary, as Cuvier remarks, "that, as in all political associations where the participation of the citizens in the government is in inverse ratio to their number, those to whom the Society intrusts its administration should exercise over its labors, and to a certain extent over the course and progress of science, an influence more considerable than can be readily conceived of by the academies of the continent." That the Society has been fortunate in the zeal and ability of those called to preside over it, will have been observed in the course of the preceding sketch. It remains to be added that, on the death of Sir Joseph Banks, in 1820, the chair was for a short time occupied by Dr. Wollaston,† followed in the same year by Sir Humphrey Davy; by Davies Gilbert, in 1827; the Duke of Sussex, in 1830; the Marquis of Northampton, in 1838; Earl of Rosse, in 1849; Lord Wrottesley, in 1854; Sir Benjamin Brodie, in 1858; and General Sabine, in 1861. The latter still worthily occupies the chair.

As something has been said above of financial embarrassments at an earlier period of the Society, it is gratifying to state, on the authority of Mr. Weld, referring to the year 1848, that this condition of things is wholly changed; besides certain tracts of land, the Society then held in the public funds upwards of £33,000; its income being derived from rents, dividends, annual subscriptions, admission fees, compositions, and sale of Transactions and Proceedings. The number of Fellows, at the same date, was 821, of whom thirteen were honorary and forty-seven foreign. The library of the Society, then containing upwards of 40,000 volumes, is extremely rich in the best editions of scientific books. Fellows are allowed to borrow books under certain regulations, though still more use is made of the library for purposes of reference.

The sessions of the Society commence in November and continue until June. At the ordinary meetings, after the usual preliminary business, one of the secretaries announces the presents made to the Society, which are so numerous that

* Whither the Society removed in 1780.

In reference to the extraordinary tact and acuteness of Wollaston as a physicist, it was said by Magendie that "his hearing was so fine he might have been thought to be blind, and his sight so piercing he might have been supposed to be deaf."

Mr. Gilbert will be remembered by Americans as having pronounced the eulogy on Smithson, contained in the first Smithsonian Annual Report.

152 ORIGIN AND HISTORY OF THE ROYAL SOCIETY OF LONDON.

their titles fill, on an average, two folio pages weekly during the session. Certificates of candidates for election are then read, and next such paper or papers as may have been communicated to the meeting. For these papers formal thanks are returned, and they become thenceforth the property of the Society. Discussion on the subject treated of in the paper follows, after which the meeting is adjourned, and the Fellows repair with their friends to the library where they partake of tea, a custom introduced, it is stated, by Sir Humphrey Davy. A conversazione ensues, which lasts until about eleven o'clock. The council meets monthly, or more frequently, if necessary. The scientific committees assemble as occasion requires. Those annually appointed are: Mathematics, astronomy, physics, chemistry, geology, botany, zoology, and animal physiology. The number of members varies from fifteen to thirty, the latter number representing that of physics which is the largest. The Philosophical Transactions are generally published in two parts, (June and November,) which form a volume, though occasionally a third or even a fourth part appears. Besides the Transactions, abstracts of the papers and minutes are published monthly, and these, now extending to more than ten volumes, are entitled Proceedings of the Royal Society.

A BRIEF SKETCH

OF THE

MODERN THEORY OF CHEMICAL TYPES.

BY CHARLES, M. WETHERILL, PH. D., M. D.

AFTER the electric current had been applied to the decomposition of inorganic bodies, and it had been discovered that hydrogen, the metals, and the bases appeared at the negative pole, while oxygen, chlorine, and the acids were manifested at the positive pole, the assumption that electrical attraction was the bond of union in chemical combinations was very natural, and the electrochemical theory growing out of these experiments became speedily adopted by chemists. The theory explained satisfactorily all known phenomena; it gained additional support from the discovery that the chemical elements and compounds were separated by electricity from their combinations in the ratio of their equivalents. In those days it was assumed, and at the present time it is manifest, that any theory not embracing organic as well as inorganic compounds would be untenable, and hence arose the radical theory, first applied to inorganic salts, but afterwards thoroughly studied and developed in respect to organic compounds.

As the present sketch is intended less for chemists than for others who may be confused at the appearance of the formulæ of organic compounds given in modern chemical essays, the author may be pardoned in citing facts and formulæ trite to chemists. He would also take occasion here to accredit to the Lehrbuch of Graham Otto many of the illustrations, as well as some of the arguments, employed in the present sketch.

The nature of electrical attraction renders the idea of binary compounds in chemistry imperative, if we assume that electricity is the bond of union in such compounds.

Berzelius imagined the elementary atoms laden with electricity and with positive and negative poles, but so that in the atom of one element the positive electricity predominated, while in that of another element the negative electricity was in excess. This excess of (+ or -) electricity communicated its characters to the element, making it positive or negative. If two atoms of different electrical character are brought sufficiently near to each other, they mutually attract each other, forming a compound atom, which is itself positive or negative according to the predominance of one kind or the other of its electricity. The new compound atom was, therefore, susceptible of further attraction by another compound atom of different electricity, and so on, the attraction becoming weaker as the compound atom becomes more complex.

Ampère imagined the atoms of positive elements to have positive nucleï with negative atmospheres or envelopes, and atoms of the negative elements to have negative nucleï and positive envelopes. Hence a positive and a negative atom upon coming together would mutually polarize each other; the + and — E of their nucleï would draw them together to form a compound, and the E of

their respective envelopes would be driven off and combine to produce the electrical phenomena always attending chemical action.*

According to this view all chemical compounds are binary; they are capable of being decomposed by the electric current, which attracts the atoms from each other according to their character, the positive appearing at the negative pole, the negative at the positive pole.

In writing formula the positive atom or atom group is placed BEFORE the

+

+

negative one, thus: KO; SO3; KO, SO3.†

The most complex formulæ are constructed according to this binary method. In alum = KO SO3 + Al2 O3 3SO3 + 24HO the sulphate of potassa atom is positive, and united to an electro-negative atom of sulphate of alumina to form a still more complex atom of positive character, which is united to the negative group of atoms 24HO. When, however, the atom becomes so complicated, it is difficult to determine the electro-chemical character of its imme

*For views as to polarity in chemical compounds, see the excellent treatise upon the catalytic force, by T. L. Phipson, Smithsonian Report for 1862, page 395.

For the convenience of those whose memory may require refreshing as to chemical symbols and combining quantities, or atomic weights, we subjoin the following table.

SYMBOLS AND PROPORTIONAL NUMBERS OF THE ELEMENTS.

(From Odling's Manual of Chemistry.)

* These elements have had their equivalents doubled to conform to the type theory.

diate constituents. In the above example the 24HO may be driven off by heat, but not by electricity simply; and from other considerations it is impossible to decide from analysis alone whether water is an acid or a base, as it possesses, according to the substance with which it is combined, each of these characters; in oil of vitriol it is a base HO SO3; in hydrate of potassa, an acid KO HO. There is still another method of imagining the grouping of the atoms in a complex atom to form a binary compound. This involves the essence of the radical theory.

SO, does not redden litmus nor form salts with bases; its compound with HO (oil of vitriol) possesses this property. We may imagine this acid to be HO, SO3, according to the principles just laid down; or to be H SO4, a binary compound, in which H is + and SO, is If for hydrogen we substitute potassium or any metal, we will have sulphate of potassa or the salt corresponding to the metal. SO, is, therefore, a compound radical in the sense in which the word has been employed in chemistry, although it has not been isolated. When water and anhydrous sulphuric acid are brought together, this compound radical is generated by the decomposition of water in the manner illustrated above. It is, however, more particularly in the case of the bases that the theory of compound radicals has been developed.

The example of ammonia illustrates an inorganic compound radical; if, indeed, it may at present be called inorganic.

The gas ammonia NH3 (in a manner analogous to that of anhydrous sulphuric acid) acquires basic properties only by the action of water; NH3, HO=NH, 0. NH is the compound radical, ammonium. It has never been isolated; it is an hypothetical group of atoms playing the part of a metal.

The following table illustrates the parallelism existing between compound and simple inorganic radicals:

When organic chemistry began to be developed, the compounds first studied were those containing different proportions of carbon, hydrogen, and oxygen, together with a few containing nitrogen. These were studied in their analogies to inorganic compounds, and the assumption of a large number of organic radicals became imperative. For example, if ether (C, H, O) were the oxide of a radical (C1 Hs) called ethyl, the compounds of ether could be brought into comparison with those of oxides of the different metals, (C, H5,) being a compound organic radical, which group of atoms plays the part of a metal, thus: