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.

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.

In several papers communicated to the Society within recent years the thermal effect of compressing water has been dealt with by various observers. The present paper gives the results of experiments of a similar kind to ascertain the thermal effects of compressing certain solids and liquids. These experiments were conducted in the University of Edinburgh, under the superintendence of Professor Tait.

The results of more than a year's study of the distribution of micro-organisms, that is, bacteria and fungi in water, are I think of sufficient interest to justify a short communication.

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.

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 electrical resistance manifested relatively by certain fused salts is peculiar. The following communication contains the result of observations on time changes of resistances noticed during the cooling and resolidification of two typical groups of fused salts and also of molten glass.

This paper contained an account of the experimental evidence in support of the theory of solution enunciated in a paper “On the Nature of Solution,” communicated to the Society in January 1883. Solution of a salt in a liquid is a consequence of the attraction of the molecules of the liquid, for a molecule of the salt (adhesion), exceeding the attraction of the molecules of salt for one another (cohesion). As the number of dissolved salt molecules increases, the attraction of the molecules of liquid for the molecules of salt becomes more and more balanced by the mutual attraction of the salt molecules. When these two forces are in equilibrium, saturation ensues.

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.

The author has recently been engaged in a variety of electrical observations in connection with wrought iron and steels, in the course of which it occurred to him to investigate some of the effects produced in the presence of nascent oxygen, of the ozone type, by a current of sufficient strength to readily decompose these metals by oxidation whilst immersed as electrodes in distilled water, the great resistance of the latter apparently facilitating the interesting results observed and recorded below.

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.