The ever-increasing importance of nitrites in medicine, owing to their power as therapeutical agents, and to the scientific work which has been and is being done to elucidate their pharmacology, renders a knowledge as to the precise amount of nitrite a commercial specimen contains of high, importance. For while to most patients a dose of five or six grains of pure, or nearly pure, nitrite of sodium is as large a quantity as they can conveniently bear, we read of twenty and thirty grains of so-called nitrite of sodium having been administered without dangerous or very unpleasant results. In such cases we cannot but conclude the drug was impure, and MacEwan has shown that samples of nitrite of sodium were met with in commerce containing but a decimal percentage of the salt. Many papers have recently appeared on the estimation of nitrite of ethyl in the spirit of nitrous ether, but in this contribution I desire only to consider those methods suitable for the estimation of nitrous acid in its inorganic compounds.

The question as to the normal duration of the life of red blood corpuscles has hitherto been considered more as a matter for speculative inquiry than for experimental proof. Attempts have from time to time been made by various observers to solve it experimentally, by injecting the blood of one animal into the circulation of another, whose blood corpuscles were of different size and shape, and then noting how long the foreign blood corpuscles remained discoverable in the body of their host. As might have been anticipated, the success of such experiments has not been very striking.

The following results of observations made with four of the thermometer screens, devised by Mr Aitken of Darroch, form the commencement of an investigation which has been begun at Granton Marine Station, and which is to be carried on there and at Ben Nevis Observatory during the summer and autumn, with the view of finding a more suitable screen for exposing thermometers for meteorological purposes, and, if possible, of determining the mean correction to be applied to the readings of thermometers exposed in the ordinary Stevenson screens. So far, the work has been entirely of a preliminary character, but some points have been brought to light which are of considerable interest.

The temperature of water can be ascertained much more easily than that of air, and with far greater accuracy; yet comparatively little has been done by meteorologists in the way of obtaining data bearing on the distribution of temperature in rivers and in estuaries. Some observations of great value have been discussed by Mr Buchan in the Scottish Meteorological Society's Journal, but these were discontinued after a few years.

To appreciate the present position of biological science, it is necessary to have a clear conception of the history. For this, abundant historical materials are indeed available, and reach their highest level in the standard works of Sachs and Carus. Such detailed histories, however, produce, by their very completeness, a measure of embarrassment. Moreover, the existence of numerous distinct lines of research, often equally prominent at the same time and in the same work, is apt to obscure the fact that the science has really had a simple and natural evolution. What the student demands is not so much any detailed chronological survey, but rather a sketch which will show how the whole system of modern biology, with its increasingly exhaustive analysis of detail, lies within a few essential lines of research, as laid down by a definite succession of original thinkers.

The foregoing paper was read on 5th July 1880. We postponed, however, its publication, feeling that however interesting the formation of the bodies therein described might be, much careful quanti tative research would have to be undertaken before any definite conclusion as to the true nature of these bodies could justifiably be drawn. Only the title of our paper was therefore published in the Proceeding of this Society. The old University Laboratory being in many respects'unfitted for the prosecution of accurate quantitative work, our researches were repeatedly postponed in the hope of being able to continue them in the new University Laboratory, which, however, only now approaches completion. This delay has been to us a subject of much regret, the questions involved being of no little interest.

When the compressibility of a liquid or gas is measured at very high pressures, the compression vessel has to be enclosed in a strong cylinder of metal, and thus it must be made, in some way, selfregistering. I first used indices, prevented from slipping by means of hairs. Sir W. Thomson's devices for sounding, at small depths, by the compression of air, in which he used various physical and chemical processes for recording purposes, led me to devise and employ a thin silver film which was washed off by a column of mercury. Much of my work connected with the Challenger Thermometers was done by the help of this process. Till quite recently I was unaware that it had been devised and employed by Cailletet in 1873, only that his films were of gold.

Telegraphic communication between-Ben Nevis Observatory and Fort-William Post Office is kept up by means of a line which consists of an ordinary telegraph wire from Fort-William to Auchintee Farm at the base of the mountain, and a cable laid underground from thence to the summit. At Fort-William the wire is put to earth in the usual way, while at the Observatory the return wire is attached to the iron-wire sheath of the cable.

During the spring of 1882 Mr Burton and I communicated some preliminary experiments on a new method of measuring the heats of combination of the metals with the halogens.

A short time ago I published a method in the Chem. News, vol. liii. p. 41, “On the use of Hydrogen Peroxide as an oxidising agent for detecting and estimating Manganese;” showing the advantages it had over other sources of oxygen for oxidation purposes, simply on account of the fact, that when using hydroxyl you do not introduce any objectionable foreign substance, such as manganese, chromium, potassium, lead, &c.