The sample of the remarkable deposit of Diatomite, upon which the subjoined observations have been made, was forwarded to me some time ago by William Morrison, Esq., of the Academy, Dingwall, through my friend Mr John Gunn. With the exception of a brief notice in the newspapers soon after the discovery of the deposit by Mr Morrison a few months ago, and a paper entitled “On some New Localities for the Mineral Diatomite, with Notes on the Chemical Composition of the Specimens exhibited,” in the Mineralogical Magazine and Journal of the Mineralogical Society, vol. vii. No. 32, pp. 30–34, July 1886, by W. Ivison Macadam, F.C.S., F.I.C., Professor of Chemistry, New Veterinary College, Edinburgh, no statistics have been published in connection with the deposit, nor has any account hitherto been given of the Diatomaceœ which play so prominent a part in its composition.

The structure of the eye in Isopods has been less studied than in any other group of Arthropods; the only modern descriptions of the minute anatomy of the eye in these crustaceans known to me are by Grenacher of Porcellio, by Bullar of Cymothoa, by Bellonci of Sphæroma, by myself of the genus Serolis. I have lately had the opportunity, while engaged upon my Report upon the “Challenger” Isopoda, of investigating the eye in several species of Æga and allied genera. The structure of the eye in these Isopods differs very materially from the descriptions given by Grenacher and Bullar, but agrees very closely with the structure of the eye in Serolis.

In the Proceedings of the Royal Society of Edinburgh for 1874–75 there is a short paper on the “Electrical Resistance of Iron at a High Temperature.” It is the record of certain experiments made by three of us, then students in the Physical Laboratory of the University of Edinburgh; and its conclusion is that there is a peculiarity in the behaviour of iron as an electric conductor at the temperature of a dull red heat. At this temperature other physical peculiarities are known to exist, particularly as regards its thermal expansion, its thermal capacity, and its specific heat for electricity. The discovery of these striking properties we owe respectively to Dr Gore, Professor Barrett, and Professor Tait.

A little more than a year ago, I was led to conclude that the primitive hypoblast in pelagic Teleostean ova was derived mainly from the unsegmented protoplasm forming the floor of the segmentation cavity. In this respect my results were mainly in harmony with the researches of Lereboullet (21), Kupffer (18 and 19), Klein (16), Van Bambeke (3), and others, but opposed to the more recent investigations of Henneguy (10), Hoffmann (14), Kingsley and Conn. (15), Ryder (24), Agassiz and Whitman (1), and Cunningham (8.) At that time I adopted Agassiz and Whitman's name of periblast for the subgerminal layer containing free nuclei, though I differed from those authors in my idea of the mode of origin of the nuclei. As, however, I regard the tissues derived from this layer as belonging chiefly to the parablastic group of His and Waldeyer, I propose to return for the present to the older name of parablast. I was not enabled to trace the origin of this layer in my earlier investigations, and thus failed to grasp its significance. More recently I have had an opportunity of studying the development of several other types, particularly the herring and cod. In the herring the germinal mound is not formed until after fertilisation. Partly owing to this circumstance, and partly also to the early period at which the assimilation of yolk commences, the eggs of the herring are particularly well suited for a study of the parablast question.

The question is the following:—We consider the solid angle formed by three planes at right angles to each other, and into the space of this single octant we introduce a given ellipsoid, and cause its surface to be tangent to each of the three sides of the solid angle. The position of the points of tangence will of course be variable in each plane according to the orientation given to the axes of the ellipsoid, but it is evident that on each of the planes the positions of the point of contact will be unable to outpass certain limits so long as the ellipsoid fulfils the condition of remaining tangent simultaneously to the three planes: these limiting positions of the point of contact in one, as for example, of the planes, will form a certain curve, and the proposed question will be: the determination of that curve, the limiting curve as we shall call it in the Sequel.

The sponge Suberites domuncula attracted the attention of the Italian naturalist Olivi almost a hundred years ago, but was on account of its firm india-rubber like consistency erroneously regarded as an Alcyonium. Beyond the general diagnosis of Nardo who erected the genus Suberites, the structure of the sponge has, I believe, remained virtually unknown. Not for this reason, however, but because the Monaxonia in general, of which Suberites is an example, are still for the most part but little known, Prof. F. E. Schulze of Berlin was good enough to ask me last winter to investigate the structure of this sponge. To him, therefore—perhaps the greatest living authority on the subject—I may be allowed to express my gratitude for the hospitable reception with which he welcomed a stranger to his laboratory, and for the constant interest and assistance with which he encouraged my work. That I have not succeeded in giving a perfect elucidation of the structure is largely due to the same cause which has kept it for so long almost wholly unknown. The crowded siliceous spicules, the compact consistence, the smallness of the ciliated chambers, make the histological analysis somewhat difficult. Such gaps as exist in my investigation I hope to be able to fill up by the study of related forms, and have with that end begun the study of Suberites mana.

During a short visit I paid to Oxford in the month of June last I had the opportunity of examining, by the kind permission of Professor Moseley, a number of specimens of Bdellostoma Forsteri, which were some of a large number brought from the Cape by Mr Adam Sedgwick of Trinity College, Cambridge. This examination showed what, from the close affinity of the two forms, was naturally to be expected, namely, that the structure of the reproductive system and the development of the reproductive elements in Bdellostoma were very closely similar to the structure and development of the corresponding parts in Myxine. A short time ago I described before the Society some ovarian eggs of Myxine, obtained at the beginning of the present year, which were approaching maturity. In these eggs there were slight projections at the poles, and on the surface of the projecting parts a number of papillæ. The projections were caused by the growth of a number of threads from the vitelline membrane within the ovarian capsule, and the papillæ were the separate elevations produced by the threads.

At the suggestion of Prof. Tait, an attempt has been made in this paper to apply the method used by him in § 21 of his paper on “The Foundations of the Kinetic Theory of Gases” to a case of the question of the distribution of energy in a system of non-homogeneous impinging spheres.

The problem may be stated as follows:—Given a very great number of smooth elastic spheres, equal and like in all respects, whose centres of figure and centres of inertia do not coincide, and the sum of whose volumes is but a small fraction of the space in which they move, it is required to find the ultimate distribution of energy among the various degrees of freedom when by collisions the system has attained a “special state.”

Since its discovery by Dumas and Péligot in 1834, methyl-alcohol has been the subject of a great many researches, and as a result we have long had a perfectly certain knowledge of its atomic composition, and a very accurate knowledge of a great many of its reactions. Yet the physical properties of the substance CH4O have not yet been determined with a satisfactory degree of precision. At this we need not wonder. For the study of the transmutations of a species a very impure specimen may suffice, and a series of such studies may leave no doubt about the correct atomic formula of the species in question, and consequently also, if it is a volatile substance, about its perfect gas density. But no other physical properties can be determined otherwise than by direct experiments on a pure specimen. And pure methyl-alcohol is very difficult to obtain. In whatever reasonable sense we may take the word “pure,” as attached to the name of a chemical preparation, “pure” methyl-alcohol must be admitted to have been little more than a chemical fiction until Wöhler in 1852 discovered his well-known (oxalate) process for its extraction from wood-spirit.

Shortly after I read to the Society my paper on “Thermal and Electric Conductivity” (Trans. R. S. E., 1878), in which I stated that the results were “by no means final, even so far as my own work is concerned,” I was requested by Sir Wyville Thomson to undertake the examination of the “Pressure Errors of the ‘Challenger’ Thermometers.” This investigation led to another on the “Compression of Sea-Water,” and allied subjects, which is not yet finished. Meanwhile, though I had prepared everything for my promised repetition of the experiments on Thermal Conductivity, the bars formerly used having been nickelised, &c, I found that it would be impossible for me to carry out the investigation. I therefore asked Mr Mitchell, who, as Neil-Arnott Scholar, had already done good and careful work on Thermal Conductivity in my Laboratory, to repeat the experiments under the altered conditions. I put at his disposal all the apparatus which was employed in the former research. The Government Grant Committee allowed a sum for the payment of a computer to reduce the results, and the observations were at once commenced. The results are now laid before the Society, and are probably as good as the method and the thermometers employed can furnish.

The analytical methods referred to in our heading are infected with numerous sources of error, amongst which until lately the uncertainty of our knowledge of the combining constant “Pt” played a prominent part. This uncertainty, it is true, has been removed to a great extent by Seubert's investigation “Ueber das Atomgewicht des Platins,” Liebig's Annalen (for 1881), vol. ccvii. p. 1 et seqq. The value 194·8 for Pt, which he ultimately adopted, falls in well with his analyses of the chloroplatinates of potassium and ammonium, and there can be no doubt that his chloroplatinates were close approximations to the ideal substances. Hence his atomic weight 194·8 must be admitted to be nearer the truth than the value 198 of Andrews, which, until lately, was so generally employed by chemists in the calculation of their analyses. But it does not follow that in, for instance, the determination of chloride of potassium “as metallic platinum,” the factor 2KCl : Pt = 0·7657, calculated from Seubert's Pt, gives a more correct result than even the factor 0·75252, which follows from K = 39 : Cl = 35·5, and Pt = 198.