phate fused and filled with hydrogen, was likewise heated

Salicylic acid, with glucose, treated in the same manner, presents the same reaction in a still more decided manner.

Hippuric acid, with glucose and sulphuric acid, gives first a clear brown mixture, in which also the blood-red colour soon developes itself; then the whole mass becomes black, and evolves a large quantity of an odourless and colourless gas. This gas is not absorbed by water nor by potash, and is inflammable, burning with a blue flame: I conclude that it is chiefly oxide of carbon. As the reaction continues from this time, after the source of heat is withdrawn, the mixture soon becomes very hot, and then sulphurous acid is given off also.

NOTE ON THE NESSLER TEST.

By J. ALFRED WANKLYN.

IN the course of the various controversies relating to the water process frequent mention has been made of the time required for the development of the Nessler colour. According to some experimenters, a few minutes suffice for the full colouration; according to others, half an hour or more is necessary.

These differences have their origin in differences in the quality of the Nessler reagent. I have known two Nessler reagents which, although in the course of hours giving the same depths of colour with the same quantity of ammonia, required very different times for the production of the colouration. One sample of Nessler reagent gives its maximum of colour almost immediately, and another sample takes a quarter of an hour or an hour for full development.

To a great extent, these differences depend upon whether or not a sufficient quantity of solution of corrosive sublimate has been added to the finished Nessler reagents Whether the Nesslerising takes a couple of minutes, or

SULPHURIC ACID BY HYDROGEN.

By G. J. WARNER, F.C.S.

FOR several years past I have used a method to avoid percussive ebullition in distillation, which I have found very satisfactory, viz., that of passing through the liquid in the retort a slow current of some inert gas which is easy of preparation. Dry air, carbonic acid, and hydrogen are those most generally applicable.

I had frequently distilled sulphuric acid in a current of air which had been previously dried over calcium chloride, but on using hydrogen I find that a large quantity of sulphurous acid is always evolved.

This reaction appears to commence at about 160° C., and the quantity of sulphurous acid formed increases with the temperature, but at no point was the decomposition complete. At temperatures near the boiling-point sulphuric acid always distilled over unchanged.

Fearing that the reduction might arise from the presence of hydrogen sulphide in the hydrogen, produced by sulphurous acid in the acid used for its preparation, I passed the gas first through a solution of lead acetate, and then over calcium chloride, when the same reaction ensued, although the lead solution was not blackened. Every precaution was taken to avoid the contact of cork or india-rubber with the acid vapour, the hydrogen being passed through a glass tube ground into the neck of the

retort.

In some measure to confirm this reaction, I heated (1) redistilled sulphuric acid in an atmosphere of hydrogen, in a sealed tube, for twelve hours, at a temperature of 205° C.: when broken, a quantity of sulphurous acid was found in the tube in the gaseous state. (2). Two similar tubes, containing the same acid in air, heated at the same time to 205° C., contained, when opened, no sulphurous acid. (3). A sealed tube, containing hydro-potassic sul

to those persons who are working the ammonia process of water analysis; and since the employment of the ammonia process has become almost universal, I have deemed it to be worth while to direct attention to the necessity of a careful preparation of the Nessler reagent. have, moreover, made arrangements with Messrs. Townson and Mercer for the supply of quick Nessler reagent at the rate of twenty shillings per litre. Those chemist. who do not feel disposed to take the trouble of making the reagent themselves have now the opportunity of buying it

Two papers on the above subject have recently appeared in the CHEMICAL NEWS, viz., one by Mr. T. L. Paterson (vol. xxvii., p. 111), and a short review of the same by Mr. A. S. Wilson (vol. xxvii., p. 225). A somewhat lengthy discussion on the same subject has also been carried on, in the pages of the "Greenock Sugar Trade Review," between Mr. Paterson and Mr. Murphy, of Liverpool, the practical results of which seem somewhat small when compared with the amount of noise made. Some of the statements made are, to say the least of it, rather novel; but it is a pity that a scientific discussion should be allowed to degenerate into mere personal wrangling, not to speak of doggerel rhymes.

With the view of satisfying myself as to the accuracy of some of the points in dispute, I have recently made a considerable number of experiments. These have been more especially directed to the determination of the moisture in samples of new char, and the presence of organic matter soluble in water,

and the development of theories, who build theory upon theory, who sometimes pile Ossa upon Pelion, and sometimes Pelion upon Ossa, are not unlike those whom Milton describes

"Who reasoned high
Of providence, foreknowledge, will, and fate,
Fixed fate, free will, foreknowledge absolute,
And found no end, in wandering mazes lost."

Thus it is that the decisions of one age and one day differ from those of another age and another day. Theories, we must remember, are but opinions; with opinions, as such, this course of lectures is not concerned. The facts of Nature, so far as they have yet been made apparent, or may be in process of being so, are our province. They change not. To those who have appealed to Nature direct, and brought from her exhaustless stores of knowledge some truths that men may utilise, is due the information which is to be brought before you.

The mode by which they have won this knowledge is exactly that pursued in our courts of law and equity, to arrive at the truth on one point, and on one point only. Look how long and tedious legal investigations seem, and yet in how few words the result is declared. Guilty or not guilty Verdict for the plaintiff or verdict for the defendant. One or other of these very brief phrases records the conclusion or the judgment of many days of patient labours and searchings for truths.

To not less careful questioning by men in years past, as well as now current, we owe all we know of the energies, the measurement and utilisation of which is to be a feature in these lectures. That cross-questioning of the keenest and clearest kind has been essential may be inferred from the fact that these energies are so co-related -so mutually convertible-that they merge and change, Protean-like, one into the other so instaneously that no one energy can be conveniently retained alone and in operation. They thus pass and interchange without (to our eyes) a signal from any magician's wand.

The transmutations of the imponderables are accomplished in a way that would have gladdened the eyes of the most profound alchemist, could he have seen as great transmutations in some of the material things in which he worked. For example, whenever energy is lost by resistance, heat is produced, i.e., when the resistance is perfect and complete, admitting of no intermediate state; e.g., if a wheel in machinery does not move easily, the consequence is heat, manifested on the shaft.

If, however, that energy can be converted into an intermediate state, then this state may be assumed-much as light from gas is an intermediate state between chemical affinity and heat. Do what we may, that from which energy results can neither be created nor destroyed.

In the case of blows by impact, as in the tongue of a bell, or the hammer on an anvil, or a clock, or a piano, or on a drum-head, or on a gong, then, whilst doubtless some part of this checked energy is converted into heat, yet a large portion is spent in the production of vibrations in matter, appreciable to our senses, and suggestive of vibrations in molecules, which our senses, aided by physical appliances, have not yet made visible, but which chemical changes, and what to the minds of science theorists of the present day is conclusive evidence, seem to point as similar vibrations in the invisible molecules and atoms of which it is assumed that bodies consist.

These remarks may suffice to explain that whilst to speak of estimating an "energy" is easy, yet to estimate that "energy" is an employment which tasks the keenest and most watchful faculties of the human mind, as well as claiming from human hands the production of some of their most exquisite and refined work.

The difficulty of the task results not so much from a solution of the simple problem which the words "estimate that energy convey, as from the incompetence alluded to of isolating and continuing the special energy and noting its operation. For no one of nature's energies,

be they ponderable or imponderable, is alone. Solitariness in the unseen, as well as in the seen, is no part of nature's plans.

Faraday seemed to have realised this view in great intensity when he wrote-"If, as I believe, dualities are essential to the forces, are always equal, are mutually dependent, that one cannot appear or exist without the other the proof of this would lead to many consequences of high importance to the philosophy of force generally.”*

This interlacing of energies, this co-relation, as it is called, of physical forces, whilst it knits in harmonious union energies which are nominally distinct, baffles the investigator who wishes to assign to each its share in any specific work. For example, the energy of gravity operates everywhere, and our fundamental principle in hydraulics, that fluids press equally in all directions, may be granted as a postulate. The experiments by which it can be confirmed may be and is very clearly described, but no one has ever made or can make them. Gravity never ceases to impress upon fluids a downward tendency, and so prevents an equality of pressures in all directions being established.

It may be in the interest of the Moslem faith to assert that, without visible means, Mahomet's coffin rests between earth and heaven; but, assuming the truth of the tradition, or of the fact (whichever it be), we know well that gravity operates in all its wonted intensity, and that the coffin is held there (if held at all) by the introduction of some counteracting energy, as that of magnetism.

The energy of electricity is ever passing into heatthat of heat into electricity or light. Electricity, again, appears to assume the form of vitality; and then, again, it totally fails to fulfil the vital conditions. In some animals the exhaustion of their muscular energy is consequent upon the exhaustion of their vital energy, and no electrical appliance can restore the vital energy, even though it seems to restore the muscular. Take affinity. This passes, by means unknown to us, into electricity and heat.

There is also this peculiarity amongst these energies. The work of one energy, estimated by any means known to us, gives no indication of the work of some other energy, resident or potential, in the same matter.

For example, the estimation of a drop of water by gravity standards-to speak of it as weighing so many grains-gives no indication whatever of its ability to promote affinities, to absorb and convey heat, to decompose light. And if even all these were known, there would still be no indication that upon an electrical standard of measurement its destructive effects are equal to that of a flash of lightning.

The only energies that may be said to be non-interchangeable are those of gravity and vitality. The former is enduring, the latter fleeting. The character of the one is persistence and constancy; that of the other, change and variety. Gravity may be said to be quietly resident in matter; vitality shows its presence by growth or motion.

Gravity is an energy pervading all nature, as intense in grains of sand as in the mountain; in a drop of water as in the river or the ocean. Disregarding alike the vitality of the plant or the animal-for gravity treats them as though they were as inert, indifferent, and unconscious of its presence as the soil of the garden, or the mineral under the earth-thus this energy, which is to occupy our chief consideration in the next lecture, is alone, and yet we shall find how that it has been left for recent times to tabulate its measure, to report and utilise, under the guidance of ordinary arithmetical and mathematical rules, the scientific and social consequences of the measure so established.

The other energy, that of vitality, which is to occupy

*Proc. Roy. Inst. for 1854, 6.

All who have questioned Nature are well aware how simply and truthfully she replies. It must, however, be steadily borne in mind that this truthfulness applies to the question and answer in their mutual relations. If the question be so put that Dame Nature has to answer in respect to the combination of two elements, and so is called upon to give a reply which is in truth the aggregate of the two, she does so. It behoves the questioner to frame his question with the utmost care, in order to eliminate what is extraneous to his purpose. All must have observed how difficult it is to frame a question which cannot be mis-read, or admit of a reply evidently based upon a view which the questioner never contemplated. For example, if the question relates to gravity, caution is needed to exclude the buoyancy and even viscosity of the air, and the centrifugal effects of the earth's rotation.

If it relate to electricity, caution is needed to exclude the most infinitesimal alloy of a metal-even a metal itself.

If it relate to vitality, caution is needed to exclude the effects of temporary exhilaration or prostration.

If it relate to affinity, caution is needed to exclude the complication of phenomena by variations in gaseous pressure or atmospheric temperature.

If it relate to heat, caution is needed to exclude peculiarly constituted substances, in their unknown and varying effects on heat from their atomic or rather molecular condition.

Although, for purposes of classification and the general distinction of the phenomena, the energies found in nature are arranged under the general energies which are prefixed to the respective lectures of this course, yet it must be borne in mind that these are verbal rather than emphatically actual distinctions. They are merely the terms recognised at the present day, and in a few years may be dismissed. The convertibility of energy just now alluded to is a phrase which conveys a clear meaning, but this convertibility is a process that cannot be followed. At one time in the science world a general principle seems to have been established in relation to it; again and again the hope fades, the principle is on no secure basis, whilst the convertibility is ever active. It may not inappropriately be asked which energy is the source of the others-which, in fact, seems to have the highest claim to be classed as the one. Doubtless, as a question of sequence, in time gravity must claim the first place, but, so far as our powers of utilising the energies of the imponderables are concerned, we are not able to appeal very hopefully to gravity. We cannot obtain the other energies from it. Gravity refuses to be converted; its political principles are of the type which permits no change. Nature's No. I must be gravity; man's No. 1 affinity. For example, oxygen and hydrogen manifest their affinities in obedience to some inexplicable law. They enter into what is called combination, and in so doing manifest one form of energy to which the name of the "energy of affinity" is given. But in the transition state-in the act of obeying the very imperfectly known laws of affinityanother energy of a different name and character appears, viz., heat. Evidence of the power of this energy-heatis furnished to tests very different to those which may be applied to the energy of affinity. The heat is presented to the thermo-electric pile, and that a great change in the mode of its energy has taken place is obvious from the results it produces at a distance; to this new form of energy we give the name of electricity. By a species of magic, electricity has called forth an energy to which is given the name of magnetism. Suitable circumstances

Thus, by change superposed on change, the energy of an imponderable has been converted into that energy of the ponderable to which we are indebted for all, or nearly all, of arts, manufactures, and commerce.

The two imponderable energies into which chemical affinity cannot be converted are vitality and gravity. These two may, as we shall hereafter find, assume the form of the others-the others cannot assume their forms —at least not in any plain and honest sense. Except in these two physical energy is a visible reproduction of the invisible doings of chemical affinity.

Simple as this process of transformation may appear, and convenient and useful as the suddenness of the change may be, it cannot be denied that to the investigator it is perplexing. Men, however, labour on, each perhaps winning a little from the unknown, and adding it to the known. Thus, although "hills peep o'er hills, and Alps on Alps arise," yet men of varied resources and patient perseverance have won those invaluable treasures of measurement and utilisation from the imponderables and unseen which give the title to this course of Cantor Lectures.

Even Livingstone has not shown a more noble resolve "to conquer or to die" than have those to whom we are indebted for all we know touching the modes of measuring the energies of gravity, vitality, affinity, electricity, light, and heat.

As illustrations of the difficulties of the tasks before them, it may suffice, in this introductory stage, briefly to observe that:

Galvanic currents may escape notice unless the intensity of terrestrial magnetism be neutralised.

Diamagnetism and the magneto-electric spark escape notice, unless a large number of galvanic cells or their equivalent is used.

What was called the " smell of electricity" led Schonbein to the discovery of "ozone," a remarkable product, and one whose energies are yet unknown, although being slowly but surely developed.

That a vibrating magnetising needle came to rest sooner in the neighbourhood of a copper plate, now called a damper, then when the plate was away, led to the discovery of the induction of electric currents by Faraday.

Opinions from telescopic appearances of the size of the stars led to an idea that their discs differed; the phenomenon has been found to be due to the diffraction of light.

The velocity of sound was calculated, making due allowance for the direction of the wind; in recent years it has been found that the heat developed by one particle of air striking another, must be taken into account.

(To be continued.

Royal School of Mines.-At a meeting of the Council, held on Saturday, July 5, the following gentlemen received the diploma of Associate of the Royal School of Mines:-Mining and Metallurgical Division-E. Jackson J. A. Griffiths, C. Law. Mining Division-A. G. Phillips. Metallurgical Division-J. W. Westmoreland, S. W. Davies, J. C. Jefferson, H. S. Bell. Geological DivisionG. Smith. The following scholarships and prizes were awarded:-The two Royal scholarships of £15 each, for first year's students, to Mr. W. Carter and Mr. A. J. Meeze. For second year's students-His Royal Highness the Duke of Cornwall's scholarship of £30 for two years, to Mr. C. Lloyd Morgan; and the Royal scholarship of £25, to Mr. S. A. Hill. The Edward Forbes medal and prize of books, for natural history, to Mr. G. Smith. The De la Beche medal and prize of books, for mining, to Mr. Edgar Jackson. The Murchison medal and prize of books, for geology, to Mr. C. Lloyd Morgan.