next memoir, and for which already materials have been largely obtained, will describe the formation as it occurs in the middle district of Scotland, under the title of Lake Caledonia; and the third district, comprehending the south of Scotland and the north of England, will be described under the title of Lake Cheviot.

It was not necessary for him (the Chairman) to refer to Professor Geikie's identification and classification of the rocks composing the strata in the Scotch northern counties, or the different fossils found in them. His object was merely to point out the nature and importance of the investigation entered on by Professor Geikie, and on account of which this prize had been awarded. He had read with the utmost interest the exposition given in the memoir, indicating, as it did, a large amount not only of personal labour on the part of the author, but of great knowledge and ability. He hoped that this prize would be accepted by Professor Geikie as a heartfelt acknowledgment and testimony by the Council of the eminent services he had rendered and is rendering to science by this work. He was sure also that the Professor would be pleased to have his name added to the roll of eminent men of science who had gained this prize in former years, at the head of which roll stands Sir Roderick Murchison, whom Professor Geikie frequently alluded to in his memoir as his "old chief," and whom they all respected not merely for his great geological discoveries, but for the substantial benefits conferred by him on our Edinburgh University, by founding in it that Chair of Geology which Professor Geikie so ably fills.

The Chairman, having then invited Professor Geikie to come forward, placed in his hands the Gold Medal and a bank cheque, adding, as from himself, that it gave him peculiar pleasure to have been called on to perform this duty.

The following Communications were read:

1. The Solar Spectrum in 1877-8; with some Idea of its Probable Temperature of Origination. By Piazzi Smyth, Astronomer Royal for Scotland.

(Abstract.)

This solar spectrum contains measures of about 2000 fixed lines, or fully a third more than are represented in Ångström's worthily

celebrated Normal Solar Spectrum Map, which is taken as the standard reference for "place." The observations were made in Lisbon during the summers of 1877-8, with apparatus prepared by the author; who aimed at including everything visible, from the extreme red to the extreme violet ends of the spectrum, so far as that is amenable to the human eye after transmission through glass.

The author also strove to include only true solar lines, with the least possible admission of such as are produced by the earth's atmosphere. Finally, he compares his so far purified solar result against upwards of 5000 observations of laboratory workers in chemistry, after reducing them to the same spectrum scale; and finds indications that the solar chemical elements are incandescent in a probably far higher temperature than-probably twice as high as-anything yet attained by man.

2. On another Method of Preparing Methylamine.
By R. Milner Morrison, D.Sc.

On a former occasion I drew attention to methyl sulphate of ammonium as a suitable material for the preparation of methylamine by heating it with quicklime. There is another and better method of arriving at the same result, the extreme simplicity of which was probably the cause of its being overlooked at the time.

A glance at the formula of methyl sulphate of ammonium shows that it is an isomer of acid sulphate of methylamine, viz. :—

Methyl sulphate of ammonium is an unstable salt, decomposable by a moderate amount of heat, while acid sulphate of methylamine is a much more stable body, hence it becomes probable that if the unstable substance be heated the atoms in the molecules of which it is composed will tend to arrange themselves in that order which is most stable at the temperature to which they are subjected, and therefore that in this case acid sulphate of methylamine will be produced.

Such, in fact, is the case. A portion of dry methyl sulphate of ammonium was heated by itself in a sealed tube to about 300° C. for about two hours, nearly the whole of the salt being converted into acid sulphate of methylamine.

When the tube, after cooling, was examined, it was found that a very small portion of the salt had undergone a complete decomposition, some carbon being set free. On opening the tube a small quantity of gas was given off, which was inflammable, and smelt somewhat etherial, with a trace of sulphurous acid. The salt had been fused, and had solidified to a crystalline mass, and now possessed a strongly acid reaction.

This salt, distilled with caustic potash, and the evolved gas collected in hydrochloric acid, the solution, evaporated to dryness on the waterbath, gave a hydrochlorate which, on heating with lime, gave off an inflammable gas in abundance, was deliquescent, soluble in alcohol, and when warm possessed the smell of methylamine hydrochlorate.

Several portions of methyl sulphate of ammonium were heated to different temperatures and for different lengths of time, in order to find out the most advantageous method of preparing the substance.

As there appears to be some regularity in the relation between the temperature and time and the amount converted from one salt into the other, I intend making further research in that direction; and for this reason I have for the present contented myself with only a platinum estimation, for the purpose of determining the amount of methylamine hydrochlorate present in the crude mixture of methylamine hydrochlorate and ammonium chloride. For the purpose of this estimation a portion of the crude hydrochlorate, as obtained by evaporating the hydrochloric acid solution to dryness, was dissolved in water and precipitated with chloride of platinum. The double chloride so obtained was washed, dried, and the platinum estimated by ignition.

The following are the percentages of platina found in the double salts obtained from four experiments under varying circumstances:(a) 25 grammes of methyl sulphate of ammonium were heated to 300° C. for 2 hours.

(b) 25 grammes of the salt were heated to 300° C. for 1 hour.

44.1 in ammonium double salt (calculated).

These numbers represent a percentage of hydrochlorate of methylamine present in the crude salt of—

This is also confirmed by the deliquescence of the crude hydrochlorates, which is in exactly the same order and very much greater in the case of (a) than the others.

3. On the Composition of " Reh," an Efflorescence on the Soil of certain Districts of India. By J. Gibson, Ph.D.

The following brief statement concerning "Reh" is chiefly derived from the Report of the Committee on Reh, November 1878:

Large tracts of country in the north-west of India have from time immemorial been covered with a white alkaline efflorescence, which renders them incapable of supporting any form of vegetable life. These tracts are called "usar "* plains, and the white efflorescence "reh." The appearance of this reh on the surface is owing to the subsoil water, which is impregnated with sodium salts, being sucked up to the surface by capillary attraction and there evaporated by the fierce heat of the Indian summer sun. The reh is often very irregularly distributed,-bald patches occurring in the midst of cultivation, or cultivated patches surrounded by reh, and this capricious distribution has rendered a right comprehension of its

* From the Sanscrit, signifying "barren land."

+ Hindee word for saltpetre.

mode of production difficult. It seems certain, however, that its appearance depends chiefly on the distance of the water-table from the surface of the ground and upon the nature of the intervening soil.

When reh exists in the soil it is more largely developed on a surface where the water level is nearer the surface; while, on the other hand, a soil of a close texture,-a clay soil, for instance,— may prevent the formation of reh by hindering the upward passage of the water, even where the water-table is comparatively near the surface. Of course anything which affects the rapidity of evaporation must affect the rapidity with which the reh accumulates, so that the cutting down of trees, and thus exposing the surface of the soil to the unmitigated action of the sun's rays, has an injurious effect and tends to promote the formation of the efflorescence. Until lately an equilibrium of reh distribution was established, at all events approximately. The great usar plains which have existed from unknown times did not increase in extent or change their position; but it would seem that by the introduction of the canalirrigation system this equilibrium has been disturbed. The Western Jumna Canal-which runs from the Jumna, where it leaves the hills, down as far as Delhi-has developed large tracts of reh, land which was formerly cultivated and fruitful being covered with it, and the same process has begun and is going on with alarming rapidity on the Ganges and Eastern Jumna canals in the country between the Jumna and the Ganges. The evil is of great magnitude, and large tracts of fertile land are fast becoming waste and unproductive, and the condition of the people and their cattle is deteriorating in consequence. Two years ago a committee was appointed by Government to discover the cause or causes of the evil, and suggest, if possible, some remedy. As the result of their deliberation, it is established beyond doubt that this new production of reh is chiefly, if not solely, caused by the system of canal irrigation as at present carried out. In the first instance, the level of the salt-impregnated subsoil water has been much raised, so as to be more readily drawn up to the surface by capillary action and there evaporated, leaving the salts it held in solution as a crust on the surface. There seems to be some difference of opinion amongst the members of the committee, as to whether this is chiefly due to percolation from the bottom and sides of the canals, which are at a