reason why a similar plan should not be carried out in this instance. The subject is so serious, that its treatment with regard to disinfection ought not to be decided by analogies between cattle plague and cholera, which are yet unproved. In a visitation of this character it is possible to try experiments of a nature wholly out of our power under ordinary circumstances; and thus it is feasible to suppose that, from the lessons derived from this pestilence, we might obtain insight into the laws governing zymotic diseases.

Although foul sewage and putrefying animal matter are probably insufficient to generate the first septic germ of a pestilence, there can be no question that when such a plague does come amongst us, it spreads with the greatest virulence wherever such putrescent materials abound. It may therefore be expected, not unreasonably, that by extending the sphere of an operation of appropriate disinfectants, we may diminish the death-rate, and materially augment the well-being of the community.

On Ozone. By Dr. DAUBENY, F.R.S.

Dr. Daubeny communicated a summary of the observations and experiments he had been making with respect to the presence of ozone in the atmosphere, the sources from which it was derived, and its uses in the economy of nature. Judging from the depth of coloration produced upon Schönbein's papers by exposure to the open air, as observed during a period extending on the whole to eight months, he inferred that the quantity of ozone at Torquay was much greater, on the average, during the prevalence of winds proceeding from the sea, than at times when they had blown over land. By the same test he had endeavoured to ascertain whether this ozone was generated by vegetation; and although he found that light alone exerted some influence in colouring the paper, in proportion to its intensity, was led to infer that, after deducting this, a certain residual effect was due to the action of the green parts of plants in generating ozone during the day; and as ozone exercises an undoubted power in removing putrid matter by oxidation, it seemed probable that the vegetable world may be thus the appointed means of destroying animal effluvia, and of thus restoring to the atmosphere its original purity when vitiated by the emanations of living beings.

On the Refraction- and Dispersion-equivalents of Chlorine, Bromine, and Iodine. By J. H. GLADSTONE, F.R.S.

The refraction-equivalent of a substance is the product of its atomic weight into its specific refractive energy, that is, its refractive index minus one divided by its density. From data previously published by the author and the Rev. T. P. Dale, together with Dulong's observations on gases, the following determinations of the refraction-equivalents of the halogens had been made.

Chlorine, as a gas, or in gaseous combination, gives the number 87; in the chloride of phosphorus it seems to be 94; while in several cases of its liquid compounds of carbon and hydrogen it ranged from 96 to 10.

Bromine, as the elementary liquid, gives the number 166; its liquid compound with phosphorus indicates only 14.5, and its compounds with carbon and hydrogen about 15.5.

Iodine, as determined from four liquid compounds of the iodide-of-methyl series, averages 24.2.

The numbers determined for bromine are nearly intermediate between those for chlorine and iodine.

The dispersion-equivalent of a substance is the difference between its refractionequivalents as calculated for the two extreme lines of the spectrum A and H. Determinations from some of the same compounds of the halogens with methyl, ethyl, &c., gave numbers, of which that for bromine lies also between those of the other two, but considerably nearer to chlorine than to iodine. The following determinations are strictly comparable:

On the Nature and Properties of Ozone and Antozone demonstrated experimentally. By J. M. McGAULEY.

On the Chemical Action of Medicines. By Dr. H. BENCE JONES, F.R.S. The law of the conservation of energy entirely does away with every supposition that medicine can create or annihilate any force. Medicines may carry latent energy into each part of the body, and they may become active within by increasing oxidation, nutrition, secretion, motion, and sensation; or by their properties they may put a check upon these functions by increasing the resistance or by altering the conditions necessary for the conversion of latent energy into active force.

The great functions of medicine are chemically to assist qualitatively or quantitatively, first the working, and secondly, the repair of the organs and structures of the body.

For clearness, only two of the chemical actions of medicines are dwelt on in this paper, namely, their influence on the two processes of oxidation and of nutrition that continually take place in each of the textures of the body. These processes are affected by medicines in at least two ways. First, directly, by the passage of the medicines into the different textures, where oxidation is promoted or retarded, and where nutrition is assisted or muscles prevented; and secondly, indirectly, by the action of the medicines on the nerves that regulate the circulation, whereby the flow of blood through the vessels is increased or diminished. The motion equals F

the force of the heart divided by the resistance M=R

On this view, the first great division of medicines consists of those which (A) directly or (B) indirectly promote oxidation, or (C) directly or (D) indirectly retard it.

A. Medicines that directly promote oxidation,-Iron; oxygen and ozone; alkalies; chlorine, iodine, bromine; permanganates?, iodates, chlorates?, nitrates ?, strong mineral, vegetable and animal irritants, as large doses of salts of antimony, copper, zinc, mercury; croton oil; cantharides; all forms of motion, including heat, light, and electricity.

B. Medicines that indirectly promote oxidation by increasing the circulation. Among the causes that determine the force and the frequency of the heart's contraction are, (1) the action of the nerves, (2) of the muscle, and (3) the chemical and mechanical quality and quantity of the blood, and its relative proportion to the system of vessels in which it is contained.

For stimulating or checking the centre of the circulation a most highly complex system of nerves exists, and a similar controlling power over the arterial capillaries exists throughout the periphery.

There are at least four different centres of nervous action for the regulation of the heart. 1. A stimulating or musculomotory centre in the heart itself; 2. an inhibitory centre there also; 3. a centre which acts through the ninth pair of nerves; and 4. another with opposite action, which acts on the heart through the sympathetic nerve. Medicines may act chemically on any or all of these centres, and thereby stimulate or check the heart's action. Thus, for example, digitaline acts on 'the centre which affects the heart through the ninth pair, for when these nerves are divided digitaline has no action on the heart.

The experiments of Claude Bernard on the sublingual salivary gland show the antagonistic action of the sympathetic and the chorda tympani. Stimulation of the sympathetic checks circulation through the gland; whilst stimulation of the chorda tympani increases the flow of blood, by which secretion and oxidation are increased also.

C. Medicines that directly retard oxidation. To this class belong all the remedies which were included in the antiphlogistic regimen. Vegetable salines; vegetable acids; mineral acids; substances which become organic acids in the system, as sugar; preparations of lead; oxide of carbon; sulphuretted, arseniated, antimoniated hydrogen; oxide of nitrogen; rest from all kinds and forms of motion, mechanical, thermal, electrical, photal.

D. Medicines that indirectly retard oxidation. These may be divided into (1) those that act upon the nerves, as prussic acid, morphia, and many other alkaloids; (2) those that act on the muscles, as rest, cold, salts of potass, lead salts, veratrine, digitaline, nicotine; (3) those that alter the qualitative and quantitative relationship of the blood to the vessels, as local and general bleedings, starvation, dilution, evacuation.

The second great division of medicines consists of those which (E) directly or (F) indirectly promote nutrition, or (G) directly and (H) indirectly retard it.

The chemical actions which are concerned in the formation of the multitude of organic substances of which the body is composed are far more complicated than those comparatively simpler chemical actions on which oxidation depends. If even now the different steps and processes, the helps and hindrances which affect the formation of carbonic acid and water in the body are not yet determined, how much less able must we be at present to comprehend the chemical actions which take place in the formation of blood-globules, bones, muscles, nerves, &c.

Many of those medicines that promote or retard oxidation at the same time promote or retard nutrition. When they are present in excess, they render the formation of different substances more rapid; and when absent, the chemical actions necessary for the formation of these substances are retarded or altogether stopped. E. Medicines that directly promote nutrition. Iron helps to form blood-globules; phosphate and carbonate of lime help to form bone; cod-liver oil and other fatty matters help to form adipose tissue. Gelatine perhaps helps to form cellular tissue; and phosphorus, still more doubtfully, promotes the formation of nervous tissue.

F. Medicines that indirectly promote nutrition (1) by increasing the action of the heart, (2) by lessening the resistance in the capillaries.-Alcohol, ether, chloroform, nitrous oxide, chloride of methyl, olefiant gas increase the action of the heart by acting on the nerves. Ammonia almost immediately deprives motor nerves of their power of exciting motion, while it intensely irritates the muscular structures. Of medicines that cause the capillaries to dilate curare is the most remarkable.

G. Medicines that directly retard nutrition, either (1) by themselves entering into combination with the organic substances of which the textures are composed, by which combination the chemical changes that would otherwise occur are stopped, or (2) by the accumulation in the textures of any of the substances resulting from the chemical changes in the textures.

Lead, zinc, silver, copper, arsenic, antimony, and in some rare cases mercury, act in small doses in the first way. Among the substances which act in the second way must be included all the different products from each texture in their downward course to carbonate of ammonia, water, and salts. Among these substances carbonic acid and carbonic oxide; organic acids from oxalic acid upwards; sugar; fat; nitrogenous substances from carbonate of ammonia, urea, kreatine, indigo; animal quinoidine, to the first products formed from the albuminous substances. H. Medicines that indirectly retard nutrition by lessening the action of the heart and increasing the resistance in the capillaries, by which actions the flow of blood through the textures is lessened.

Four different actions may be distinguished, by any of which nutrition may be lessened:-1. By an action on the nerves of the heart, as by strychnia, nicotine, conicine, digitaline; 2. by an action on the muscular structure of the heart, as by veratrine, colchicine, salts of potass; 3. by contraction of the capillaries in consequence of an action upon the sympathetic nerve, as by morphine; 4. by the reduction, quantitatively or qualitatively, of the state of the blood, as by bleeding, starvation, excessive dilution, lead salts, mineral and organic acids.

The actions of oxidation and nutrition are mutually dependent everywhere, and no separation of these two actions in any part of the body actually takes place, although, for clearness, I have considered them separately. The progress of all accurate knowledge of the actions of medicines depends on exact chemical and physical experiments; and by the perfection of these alone will the practice of

medicine lose its doubts and difficulties, its disagreements and deceptions, and become esteemed by all as the art that can confer the highest benefit upon mankind.

On a Magnesium Lamp. By H. LARKIN.

The distinguishing peculiarity of this lamp is that it burns magnesium in the form of powder, instead of riband or wire, and does not depend on clockwork or any similar extraneous motive power for its action. The stream of the metal powder is mixed with a small portion of gas and fine sand in its progress through the tube; they escape together at its mouth, where they are ignited and continue burning with a brilliant flame.

On the Accumulation of the Nitrogen of Manure in the Soil.

By J. B. LAWES, F.R.S., F.C.S., and J. H. GILBERT, Ph.D., F.R.S., F.C.S. The authors had been engaged for many years in an investigation in the course of which they had grown wheat year after year on the same land for more than twenty years; on some portions without any manure, and on others with farmyard manure, or with various descriptions of manure. They had published the results obtained in the field during the first twenty years of the experiments*, and they had been for some time, and were still engaged in investigating the composition of the produce grown under the different conditions, and also the comparative composition of the soils of the different plots as affected by the various treat

ment.

The point to which they chiefly confined attention on the present occasion was the accumulation, and the loss, of the nitrogen which had been supplied in the manure and not recovered in the increase of crop. After discussing the difficulties of sampling, preparing for analysis, and analyzing soils in such manner as to yield results applicable to the purposes of their inquiry, and describing the methods they had adopted, they called attention to some of the results obtained, summaries of which were brought to view in Tables hung up in the room. percentage, and calculated acreage, amounts of nitrogen existing in such condition as to be determinable by burning with soda-lime were given for the soil of the first, of the second, and of the third nine inches, of eleven differently-manured plots, showing the amounts, therefore, to the depth of 27 inches in all.

Tae

The accumulation of nitrogen from the residue of manuring was found to be, in some cases, very considerable; but even with equal amounts supplied, it varied, both in total amount and in distribution, according to circumstances; the depth to which the unused supply had penetrated being apparently influenced by the character and amount of the associated manurial constituents. The general result was, that, although a considerable amount of the nitrogen supplied in manure which had not been recovered as increase of crop was shown to remain in the soil, still a larger amount was as yet unaccounted for. Initiative results indicated that some existed as nitric acid in the soil, but it was believed that the amount so existing would prove to be but small. In fact, it was concluded that a considerably larger proportion would remain entirely unaccounted for within the soil to the depth under examination than was there traceable; and the probability was, that at any rate some of this had passed off into the drains, and some into the lower strata of the soil. Finally, it was shown, by reference to field results, that there was not more than one or two bushels of increase in the wheat crop per acre per annum, due to the large accumulated residue of nitrogen in the soil, notwithstanding its amount was many times greater than that which would yield an increase of twenty bushels or more, if applied afresh to soil otherwise in the same condition. On the other hand, it was shown that the effect of an accumulated residue of certain mineral constituents was not only very considerable in degree, but very lasting.

"Report of Experiments on the Growth of Wheat for Twenty Years in succession on the same Land," Journ. Roy. Ag. Soc. Eng. vol. xxv. pts. 1 & 2.

On the Sources of the Fat of the Animal Body. By J. B. LAWES, F.R.S., F.C.S., and J. H. GILBERT, Ph.D., F.R.S., F.C.S.*

In 1842, Baron Liebig had concluded that the fat of Herbivora must be derived in great part from the carbo-hydrates of their food, but that it might also be produced from nitrogenous compounds. MM. Dumas and Boussingault at first called in question this view; but subsequently the experiments of Dumas and MilneEdwards with bees, of Persoz with geese, of Boussingault with pigs and ducks, and of the authors with pigs, had been held to be quite confirmatory of Liebig's view; at any rate so far as the formation of fat from the carbo-hydrates was concerned. In 1864, however, at the Bath Meeting of the British Association, Dr. Hayden, of Dublin, read a paper before the Physiological Section, in which, basing his conclusions upon certain physiological considerations of a purely qualitative kind, he expressed doubt on the point. In August 1865, again, at a meeting of the Congress of Agricultural Chemists, held at Munich, Professor Voit, from the results of experiments with dogs fed on flesh, maintained that fat must have been produced from the nitrogenous constituents of the food, and that these were probably the chief, if not the only source, of the fat even of Herbivora. In the course of the discussion which followed, Baron Liebig disputed this conclusion; and his son, Hermann von Liebig, has since written a paper on the subject, in which, illustrating his views by reference to experiments with cows, he admits the probability that fat may be formed from nitrogenous substance, but nevertheless concludes that this is neither the only nor even the chief source of fat, in the ordinary feeding of Herbivora.

The authors agreed with the conclusions of these latter authorities. The data cited by Hermann von Liebig did not, however, afford conclusive evidence on the point; and they considered that the results of experiments with cows were, in several respects, less appropriate for the purposes of the inquiry than those with some other animals. They showed, illustrating the various points by reference to experiments of their own, that, compared with either cows, oxen, or sheep, the pig had a much less proportion of alimentary organs and contents, consumed food of a much higher character, produced a much larger amount of fat both in relation to a given weight of animal within a given time and to the amount of food consumed, voided a much less proportion of the solid matter of its food in its solid and liquid excretions, and, finally, its increase contained a larger proportion of fat. For these reasons results obtained with pigs must be much more conclusive as to the sources in the food of the fat which they yield than those with either cows, oxen, or sheep. Tables were exhibited showing the results which had been obtained by the authors in numerous experiments with pigs; and from these the following main conclusions were drawn :

1. That certainly a large proportion of the fat of the Herbivora fattened for human food must be derived from other substances than fatty matter in the food.

2. That when fattening animals are fed upon their most appropriate food, much of their stored-up fat must be produced from the carbo-hydrates it supplies.

3. That nitrogenous substance may also serve as a source of fat, more especially when it is in excess, and the supply of available non-nitrogenous constituents is relatively defective.

On the Poisonous Nature of Crude Paraffin Oil, and the Products of its Rectification upon Fish. By STEVENSON MACADAM, Ph.D., F.R.S.E., F.C.S., Lecturer on Chemistry, Surgeons' Hall, Edinburgh.

The great extension of paraffin oil-works, both crude and refined, during the last few years, has led to attention being directed to the nature of the discharges which emanate from such, more especially to those matters which find their way into rivers which form the natural drainage of the district. The deleterious nature of these discharges has manifested itself already in the total destruction of all fish in more than one of our Scottish streams, and to the impregnation of the water with paraffin oil, and the products of its rectification, to such an extent as to impart the characteristic taste and odour of paraffin to the water, and render it unsuitable for domestic purposes.

* For fuller report, see the Philosophical Magazine for December 1866.