It also accounts for cases of isomerism, such as the two succinamides, which will probably have the configurations

Formation of the Sodium Compounds. In the course of numerous attempts to prepare pure Na acetanilide, one experiment gave an unexpected result, and it appears to me not only to bear out the above view of the constitution of these bodies, but to throw some light on the formation of the sodium compounds.

If acetanilide is dissolved in dry ether, and one molecule of solid sodium methylate is added, the liquid becomes turbid, and a compound of the formula CH,N. C(OH)CH,.CH,OÑa separates out in needles. The two molecules are very loosely attached, and the acetanilide may be easily dissolved out from the other substance. The formation of this compound points to the following: 1. Acetanilide is an unsaturated compound.

2. The formation of the sodium compounds in the case of anti compounds is preceded by the formation of addition compounds, with subsequent loss of one ipolecule of water, thus:

CH,N+ NaOH=C ̧H ̧Ñ . Na= CH ̧N . Na+ H2O

The experimental part of the work has been carried out in conjunction with Mr. Archdeacon, and will shortly be communicated to the Chemical Society.

7. Report of the Committee on the Bibliography of Spectroscopy. See Reports, p. 161.

WEDNESDAY, AUGUST 15.

The following Reports and Papers were read:

1. Report of the Committee on the Action of Light on Dyed Colours. See Reports, p. 238.

2. Report of the Committee on Isomeric Naphthalene Derivatives. See Reports, p. 268.

3. A Discussion took place on Dr. J. B. COHEN'S Paper on the Constitution of Acid Amides.-See p. 625.

4. On Certain Phenomena occurring during the Evaporation of Salt Solutions. By Dr. W. MEYERHOFFER, Vienna.

When a solution is partially evaporated it is not necessarily the case that the solid dissolved salts are also precipitated. From the closer examination of what

occurs when such a solution is evaporated, the four following cases may be distinguished:

(1) Solutions of a single salt.

(2) Solutions with two or more salts, all of which contain the same acid or basic radical, and form neither double salts nor isomorphous mixtures. (3) Two salts that are in a condition to form a double salt.

(4) So-called 'reciprocal' salts, i.e., salts which can be formed from two acids and two bases.

Cases 1 and 2 present nothing calling for special notice. In the case of 3, it is shown under what conditions a pure double salt crystallises out of the solution. Similarly, in the case of 4, instances are discussed in which either two or three salts result by evaporation, and an account of new experiments with NH4Cl + NaNO, in this relation is given. Lastly, the study of the occurrences which are discussed in the paper is recommended in respect to many technical processes, and the formation of natural salts.

5. On some Derivatives of Camphene. By J. E. MARSH and J. A. GARDNER.

6. On Fluorene Diacetate.

By Professor W. R. HODGKINSON and A. H. Coote.

In some previous communications to the Chemical Society by one of us, halogen and other derivatives of fluorene have been described. With the exception of diphenylenketone, there is no derivative in which it is for certain known that the methylenic hydrogen is replaced. When solutions of fluorene, dibenzyl or acenaphtene are acted upon by chlorine, bromine, &c., substitution invariably takes place in the benzenoid nucleus.

From the results of some experiments made by one of us on the sulphonates of fluorene and acenaphtene dissolved in strong HSO4, it appeared probable that dry chlorine might act upon these hydrocarbons in the absence of a solvent, and perhaps at some high temperature in a similar manner to its action on toluene, &c.

Experiment proved this to be the case.

The hydrocarbons were dried and treated with very dry chlorine at the ordinary room temperature, and also at or about the boiling-point of the respective hydrocarbons. Action commenced immediately, and a tendency was noticed for the chloride produced to distil over in the current of chlorine.

The action is, however, not quite confined to the methylenic hydrogen, for the chlorides first produced act as solvents for the still unacted-upon fluorene or acenaphtene, and some substitution in the benzene nucleus takes place. The amount of this can be reduced by letting the chlorine act rapidly.

By careful distillation under reduced pressure it is possible to effect a partial separation. A better plan is to dissolve in absolute alcohol, and fractionally crystallise by cooling with a CO, alcohol bath.

From fluorene the following bodies appear to be produced:

Acenaphtene is converted almost entirely into a dichloride. None of the chlorinated fluorene products gives diphenylenketone when oxidised under the same conditions as produce diphenylenketone from fluorene.

One fraction of the chlorinated fluorene which distilled under about 300 mm. at 320° to 330° C. gave 29°.52 per cent. Cl; the calculated amount for C1HCl, is 30.23 per cent.

A diacetate was prepared from this by digesting with alcoholic potassium acetate. On analysis this gave 71.23 per cent. carbon and 3.92 hydrogen-C1,H3. (CH,CO2), requires 72-3 C and 4.9 H. This product boiled at 326° to 330° C. at 760 mm. pressure.

A large quantity of the crude chlorination product was digested with acetate. From the result several bodies have been separated by fractional distillation, a comparatively easy process, since the acetates are much more stable than the chlorides.

A fraction at 322° C. gave 72.61 C and 4.28 H. Therefore nearly pure diacetate. We have some proof that a chlormonacetate is also formed as well as some chlorinated diacetates. Of these we have isolated one product, which on analysis gives (I) 11.01 per cent. Cl; (II) 114 per cent. Cl: C12H,Cl.(C2H2O2)2 requires 11.2 per cent. Cl. It melts at about 60° C.

Acenaphtene diacetate distils at about 290° C. and melts at 46°.

We are obtaining larger quantities of these acetates-fluorene, acenaphtene, and dibenzyl-in order to study them further.

7. Interim Report of the Committee to inquire into the Proximate Chemical Constituents of the various kinds of Coal.-See Reports, p. 246.

8. Interim Report of the Committee on the Properties of Solutions.

9. Report of the Committee for preparing a new Series of Wave-length Tables of the Spectra of the Elements.-See Reports, p. 248.

SECTION C.-GEOLOGY.

PRESIDENT OF THE SECTION-L. FLETCHER, M.A., F.R.S., F.G.S.

THURSDAY, AUGUST 9.

The President delivered the following Address :

WITH an anxious desire to conform to the traditions of the past, I have sought in the Reports of the Association for guidance in my present difficulty, and, doing so, have remarked that it is customary for a president, on first taking the Chair, to express a deep sense of unworthiness for the position to which he has been called. My first duty, then, seemed a simple and obvious one; till I further remarked, to my dismay,that the more able and distinguished the President the more humble have been the terms in which such expression has been made. Hence I feel that it may appear to you presumptuous on my part if I myself make any apology at all, and it would doubtless imply a claim to the highest ability and distinction were I to make that humble apology which would be really appropriate to the circumstances of the case.

Instead, however, of dispensing with the apology altogether-that might be too radical an innovation to be introduced this year-I propose, with your sanction, to make a lesser change, and merely to defer the apology from the first to the last day of our session. I may reasonably hope to be able, at that later stage, to make clear to you, by simple reference to your own experience during the Meeting, that the apology I shall then feel it my duty to make is of no merely formal character, but one which is worthy of your serious consideration.

I would ask that in the meantime your continuous sympathy be extended to one who now finds himself in a position he would have been the last to seek, and whose ordinary duties in life involve speechless communion with inanimate Nature rather than oral address to an assembly of fellow-workers.

This matter of apologetic precedent being thus disposed of to our common satisfaction, I should have preferred to have brought the delay of the normal business of the Section to an immediate end by calling upon the author of the first paper to now address you. Such, indeed, was the ordinary course of procedure in the earlier, and perhaps presidentially happier, years of the Association; but the occasion of taking the chair having been once seized upon, in absence of mind, by a mathematical president for the delivery of an address, it has come about that each president now feels it his bounden duty, not merely to give an address, but to make that address at least as long and at least as elaborate as any which has preceded it.

We shall all agree that a presidential address, if there is to be any at all, should be elaborately short and elaborately simple; it should deal, not with technical details such as are only intelligible, even to the president himself, after much study, but with general principles such as can be immediately grasped by every member of an audience: an opening address which is so long that it can be only partly read, and is written to be studied afterwards in the Reports of the Association, may more appropriately be issued as an ordinary memoir. I make this remark

to safeguard the interests of future audiences, for the example of technicality which I am now about to set is one which I cannot recommend my successors to follow.

As for subject, a record of recent scientific progress is always interesting and instructive, and immediately suggests itself as the natural basis of a presidential address. But seeing that, so lately as in February last, the geologists have had the advantage of an address from the retiring president of their Society, Mr. Hudleston, which has been virtually exhaustive in its survey and criticism of the British geological work of the last seven years, the time has scarcely yet arrived when a continuation of that review by the president of this Section can be of service to the members of the Association.

For this and other still more weighty reasons which I need not directly mention, I feel myself debarred from undertaking any review of recent geological discovery, and shall therefore ask you to allow me to confine myself, in the remarks it is my duty to make, to a science which, though it is not purely geological, and in the Reports of the Association has long been associated with the science of another Section, Chemistry, is yet very closely related to the science of our own Section, Geology.

I trust that the members of the Section of Chemistry and Mineralogy are now so closely engaged in another place that they will fail to discover, or at any rate to resent, the technical trespass on their own domain: as for yourselves, you will perhaps be more ready to pardon the temporary excursion from the field of pure Geology if I remind you that the Fathers of the Geological Society defined their sole object to be the investigation of the mineral structure of the Earth; and I may add, if further defence be desired, that in the first half of this century the relationship of Mineralogy and Geology was so intimate that it was possible for a Section of the British Museum to be long officially designated 'the Department of Mineralogy, including Geology.'

I was the more impelled to choose this subject for our consideration to-day when I reflected that pure Mineralogy has been hitherto almost completely out of sight, and therefore probably out of mind, at the Meetings of the Association. It is true that at the first Meeting, held sixty-three years ago, Mr. Whewell, then the Professor of Mineralogy at Cambridge, was invited to draw up a report on the state of knowledge of the science, and that his report was submitted and printed in the following year. But in the course of the sixty-three years during which the Association has flourished, it has chanced that a devotee of pure mineralogy has on only one occasion, that of 1862, been seated in a presidential chair; and since at that time presidential addresses had not yet come to be regarded as necessary to the existence of the Sections, Professor Miller, with admirable discretion, refrained from inflicting a mineralogical dissertation on an audience which, he had reason to presume, must consist entirely, or almost entirely, of chemists.

Perhaps you might be tempted to think that the want of prominence of the mineralogists at our previous Meetings has been due to a becoming sense of modesty resulting from the study of that science: this would be a mistake. The fact is that a mineralogical memoir, dealing largely with numerical quantities and involving great variety of experiment and technicality, may be read and studied. but should never be heard; like the mathematician, the mineralogist despairs of making clear to an audience, especially a mixed one, the bearing of any researches which have been made in his subject. But now that sixty-two years have elapsed since the issue of Professor Whewell's Report, the time has perhaps at length arrived when it is advisable, notwithstanding the difficulties surrounding an oral treatment of Mineralogy, to attempt to give to the Association a faint idea of the present position of the study of the subject. And if most of my hearers find that the remarks are too technical to be in any great part intelligible, let them console themselves with the reflection that, if the future at all resembles the past, only Shalum and Hilpa can have to endure again that particular kind of mauvais quart d'heure which is to precede the Geological Feast of to-day.

The Systems of Crystallisation.-At the time of the publication of Professor Whewell's Report it had already been established by the researches of Romé de