the latter form being impracticable, they have not given that information to the public which the public have a right to demand at the hands of a patentee, or rather that they have informed the public that the result can be obtained by either of two processes when one, only one of them will produce it, and that therefore not having fulfilled their part of the bargain their patent fails.

I have endeavoured to state my conclusions of law and also my deductions from the evidence with the least possible use of technical terms, because I have thought it best so to do. I have even avoided the formula Mn. Og and many other standard formulæ and chemical terms. I hope, however, that those who prefer to read technical language will find no difficulty in translating my judgment into it.

Although this action has been in substance one by Messrs. Spence against the plaintiffs for an infringement of Messrs. Spence's letters patent, yet it is only so in substance and not in form. It is not an action for infringement within the meaning of the Patent Act, 1883. I am not therefore, in a position to give any certificate.

There will be judgment for the plaintiffs for an injunction restraining continuance of the threats of which they complain, and awarding payment of forty shillings damages, and the defendants must pay the costs of the action to be taxed on the higher scale.

Mr. Aston: My lord, do not we get the costs as to infringement ?

Mr. Moulton: They have no legal rights.

Mr. Justice Kekewich: I do not quite understand you, Mr. Aston.

Mr. Aston: On the question as to whether there was not an infringement, in fact.

Mr. Justice Kekewich: That only arose on the threats. Mr. Aston: Yes, my lord, but there were expenses in connection with it.

Mr. Justice Kekewich: I dare say. That arose on the threats which I decided against you. I took that into consideration in connection with the threats. It is only a small, subordinate part of that question which I decided against

you.

N an article upon another page dealing with the new gallons of gas-tar consumed per hour generated power equal to 35 horse indicated, but the diagrams which have since been taken show most clearly that the net result is more nearly 40 indicated horse-power, and that the maximum result has not been reached yet. We will take it for our purpose that 40 horse-power is the normal development, and carry our readers with us in a few calculations to show the importance of a careful study of this subject.

The most general source of illumination in this country is coal-gas, and we may take it without sensible error that 10,000 cubic feet are obtainable from each ton of coal. Without any admixture of cannel, ordinary gas will not when burning from a London Argand burner, yield more light on the average than 18 candles from a consumption of five cubic feet per hour. To be on the safe side, let us call it 20, which is equivalent to four candles per cubic foot. By means of the "Wenham" burner as much as eight candles may be developed from each cubic foot of gas consumed, so that with ordinary burners we have 40,000 candles per ton of coal and with the Wenham" burners 80,000. Two hundredweights of coal will therefore give 4,000 candles and 8,000 candles respectively, and a hundredth part of a ton one-tenth of these amounts, or 400 candles and 800

candles. Why we have chosen this standard of one-hundreth of a ton will appear presently.

For out-door illumination the "luminator," "lucigen," and other lights have been largely used of late, and with a consumption of two gallons of tar-oils per hour the light is stated to be one of over 3,000 candles intensity. The light afforded by either of these pieces of apparatus is certainly very great, but whether it reaches this large figure or no, we have not any authentic information. Two gallons of light coal-tar will weigh about 22 4lb, or the one-hundreth part of a ton.

The electric light depends mainly upon a cheap supply of power for the development of electrical energy. We have already shown that on the Hargreaves system, that a 40 horse-power engine may be run against its full load at the expense of two gallons of coal-tar per hour, or 22.4lb. as as against 160lb. of coal if burned under boilers in the ordinary way, an efficiency at least seven times as great as in the best form of modern engine consuming 4lb. of coal per indicated horse-power per hour. It may be that some are doing better than this, but we feel sure that the majority of steam users do not come up to it.

Now, in electric glow-light installations it has become an established fact that one cannot safely reckon on more than 150 candles per horse-power per hour, and similarly when the arc-light is used, 1,500 candles per horse-power is the maximum limit, so that by using the Hargreaves thermomotor wherewith to drive the dynamo, two gallons of tar, the equivalent in weight of one-hundreth of a ton of coal, would produce an illumination by means of glow-lamps of 6,000 candles, or by means of the arc light 60,000 candles.

These figures are sufficiently startling to lead us to believe that we are on the brink of a great revolution in the lighting of large establishments, but the time has not yet nearly arrived when we can look forward to domestic lighting by means of electricity, not because it cannot be done, but on account of the conflicting interests that stand in the way. But this cheap source of power for the production of electricity is likely to cause its extension in other quarters; day by day it is being more extensively employed in metal deposition other than in plating operations, as may be seen by the recent reformation of the Electro-metal, Extracting, Refining, and Plating Company Limited, which is soon to carry on business on a larger scale than ever. For the deposition of copper from its solutions we have it on very good authority that a 40 horse-power engine will deposit nearly three tons of copper per day, and if the dynamo be driven by an engine consuming only two gallons of tar per hour, what on earth can compete against it, save perhaps the mill-stream, which cannot be brought to every man's door?

In a previous number we had the opportunity of saying a few words upon the Hermite process of bleaching by electricity, and we stated that the principal objections urged against it were cost of electricity and the secondary decompositions which took place. We see no reason why the secondary reactions cannot be overcome, and being supplied with a cheap source of electrical energy, we see no reason why even a low efficiency should militate against its introduction,

We have introduced the foregoing examples as being amongst the most striking occurring to us at the moment. They form good subjects for comparison, but there remain many instances quite as striking. If once the user of power realises the fact that he can drive a large engine of 40 indicated horse-power and upwards with a consumption of two gallons of gas-tar per hour, costing a penny per gallon, and pro rata, without chimney shaft or boiler, without stoker, without water supply, without creating any smoke, in fact sans anything save the engine itself, the problem of the amelioration of the atmosphere of our manufacturing centres will stand a good chance of being solved, and the economy of materials employed in the production of motive power will have begun in earnest.

FIRES WITH NEW PROCESSES.-Some time since the new ammonia-soda process of Messrs. Mathieson and Co. was destroyed by fire. We have now to chronicle a serious fire in the new processes of the Lancashire Sulphur and Alkali Co. at Widnes.

THE MANCHESTER CHEMICAL CLUB.-After a few months' sojourn at the Grand Hotel, this club has taken up its quarters at the Victoria Hotel. On Tuesday last there was a fair gathering of members after they had come off 'Change, so that there seems every chance of continued prosperity.

IN

N the third number of our first volume we had occasion to refer to the Hargreaves thermo-motor, as a recent device for converting a larger proportion of the heat of combustion of fuel into dynamic energy.

At that time experiments were still in progress, and we felt bound to observe a certain degree of reticence as to some details which had come to our knowledge which Mr. Hargreaves was then elaborating. It is somewhat amusing to observe the absolute ignorance or incredulity of the engineering press with respect to this motor, the so-called "leading' ones never having even so much as mentioned it! and yet it is only a solution of the problem given by Carnot, Thompson, Joule, Rankine, Dalton and others, whom they regularly quote as authorities on thermo-dynamics, and what is more, seems to have been worked out strictly on the lines foreshadowed by these philosophers. Mr. Hargreaves, in fact, disclaims having added a single scientific fact to what was already known, and claims only to have transferred the problem from the laboratory to the machine shop. This, however, has required the most dogged pertinacity and perseverance for nearly six years, which have been exclusively devoted to this work.

Since our former article a new engine has been constructed by Messrs. Adair and Co., of Liverpool, which embodies improvements not contained in the experimental engine at Widnes, The suggestions which we ventured to make in our article as to radiation, heating surfaces, and area of passages have evidently been attended to with most satisfactory results. Mr. Hargreaves has been fortunate in his choice of an engineer to carry out his ideas, for the machine is very creditable to the maker, and a great contrast with the one upon which the previous experiments were conducted. Indeed, when looking at the latter, some of our engineering contemporaries would wonder how any results were ever got out of it at all, for most of them seem to estimate the value

of an apparatus, not by the correct application of the physical forces which actuate it so much as by its mechanical "get up" and polished surfaces. To the Chemical Trade Journal belongs the credit of first appreciating the value of the methods adopted by Mr. Hargreaves. When making the suggestions referred to, we also ventured to predict that their adoption would be followed by notably increased efficiency, the following facts show that our anticipations were correct. The volumes swept through by the working piston and air piston are precisely the same as in the experimental engine, but whilst the first engine gave only 297 horse-power from a consumption of two gallons of coal-tar per hour, the new engine gives at least 35 indicated horse-power from the same consumption of fuel.

The construction of the engine now running in Liverpool may be seen from the accompanying illustration. The cycle of operations is as follows: Air is compressed in an inverted air compressor along with a finely divided spray of water. The heat developed by compression of the air is in great part absorbed in molecular work, by converting some of the water into vapour, and another portion in raising the temperature of the remaining water. The vapour produced of course adds to the volume of the gases, but this is more than compensated for by the contraction due to the cooling produced by the evaporation of water, hence the curve of compression is below the adiabatic but above the isothermal line, being about one-third the distance above the former, and two-thirds below the latter. The temperature due to adiabatic compression up to 60lb. per square inch above the atmosphere with an original temperature of 60° F. would be 380° F. With the method adopted by Mr, Hargreaves the temperature rises only to about 160° F., while the vapour tension of the water diffused through it is 4'7lb. per square inch. It is owing to this reduction of temperature that it is possible to reduce the final exhaust to the low temperature of 180° F.

before finally rejecting it, while at the same time the negative work of the air compressor is considerably reduced.

From the compressor the air carrying finely divided water with it, flows into a vessel called the saturator, traversed by copper tubes through which pass the exhaust gases from the working cylinder. The heat left behind by the exhaust gases is expended, partly in heating the air, and partly in converting the suspended spray into vapour and diffusing it amongst the air according to Dalton's law. From the saturator the air passes to another tubular vessel called the superheater, where the saturated air is dried and superheated, and a quantity of steam added from a source to be afterwards described. Hence, the mixture of air and vapour passes through the inlet valve and through a regenerator. Here it comes first in contact with some corrugated metal plates, and afterwards with spiral earthenware rods, then through a block of fireclay perforated with small holes. By the time the air and vapour has arrived at this point it has attained a red heat, when there is injected a small jet of coal-tar, creosote, or other liquid fuel. Here the volume of the mixture of air and vapour is still further expanded, combustion takes place in air already heated to redness, and hence the temperature would be sufficient to fuse even the most refractory of all the materials used in the construction of the engine; but this temperature is somewhat modified by the presence of water vapour, which absorbs a portion of the heat in elevating its own temperature and increasing its volume. Another portion of the heat is absorbed by a water jacket surrounding the cylinder, and by a quantity of water contained in the hollow piston. The water passed through the air pump is in excess of what can be diffused amongst the air by the heat from the exhaust gases; this excess of water collects at the bottom of the saturator and is taken hold of by a small pump and made to circulate, first, through the piston, and afterwards through the water jacket surrounding the working cylinder. In the piston and jacket the water is converted into steam, which is also added to the air in the superheater and so increases the volume of the working fluid and moderates the intense temperature caused by the combustion of the liquid fuel.

After the piston has performed its outstroke the products of combustion are exhausted through the regenerator, then through the heating tubes of the superheater and saturator. The temperature is continuously decreasing from the working cylinder to the chimney, while the entering air together with the diffused vapour and added steam arrive at continuously hotter and hotter surfaces on their way from the air pump to the working cylinder, and thus attain a bright red heat before arriving at the point of combustion. It is not very practicable to measure the temperature of the contents of the working cylinder by pyrometers, but an approximate estimate may be made from the volumes and pressures of the working fluid at various parts of the stroke. This shows the temperature to be about 2,500° F. while the temperature at the exhaust is less than 180° F., thus showing considerably greater temperature differences than those we had to record about the experimental engine at Widnes.

The thermal problem thus solved was not sufficient to produce a practical engine. It was necessary to keep the rubbing surfaces of the piston packing rings, the valves and their glands and packings at reasonably low temperatures, and free from grit and abrading materials. In the case of the packing rings of the working cylinder, the temperature is actually lower than in the steam engine. The boiler part of the working cylinder is used as a combustion chamber, while the piston is practically a steam boiler hung from the junk ring, while the upper part of the working cylinder is kept apart from the lower portion by a sheet of asbestos. In this upper part, which is open at the top, the junk ring works, and it is also separated from the boiler piston by a sheet of asbestos. The mirror-like surface of the working cylinder is alone a sufficient indication that no gritty materials have acted upon it, and the lubrication is not at all injured by heat. working valves are placed between the superheater and the regenerator, the inlet valve being exposed to a current of air vapour at 220° F. and the exhaust to a current at 460 F., with a variation above or below of about 20° F., according to the supply of fuel, amount of work on the engine, etc. The highest of these temperatures is not sufficient to do any injury to the exhaust valve, which is one of ordinary mushroom shape; but as a matter of fact this valve never attains the higher temperature, because the inlet gases flow over one surface and return a part of its heat to the regenerator and working cylinder.

The

As the total consumption of fuel is so small there is little

room for waste, for a very small loss would amount to a large proportion of the total heat from the fuel, hence there is no stifling heat from the motor, and such an appliance to a steamship going through the tropics would be a perfect godsend to every one on board.

In our opinion Mr. Hargreaves might have improved the proportions of his working parts by giving the working piston a little longer stroke, with the same volume of air pump and the same quantity of fuel supply. The gases are rejected at a terminal pressure of 12lb. per square inch, with six inches more expansion an addition of fully five horse-power might have been obtained from the same quantity of air and fuel. There are many hot-air engines whose maximum pressure is lower than when the working fluid is rejected in this

case.

It is a pity to see so much power wasted when it might have been saved by a little difference in proportions; judging from the indicator cards, too, still a little more freedom in the passages would not be amiss. Perhaps Mr. Hargreaves will take these hints into consideration when designing another engine.

In another article we have pleasure in putting before our readers some of the practical bearings of this thermo-motor, and the results capable of attainment are sufficiently startling to cause an immediate and general inquiry on the part of the steam using public. On the other hand, shale-oil distillers, tar distillers, and coke-oven proprietors may find it in their interest to follow what might be done in the future with this thermo-motor, and gas engineers may with profit turn their attention to it also. To tar distillers at the present time the subject is of more than ordinary interest, as coal-tar pitch dissolved in creosote is the very best fuel which could be employed with this motor, provided it is made fluid enough to flow through pipes.

Correspondence.

ANSWERS TO CORRESPONDENTS.

D. S. C.-We shall be pleased to receive your letter on "Christmas boxes for publication.

A. R. C.-Yes. The bleaching of oils and fats comes under the list of subjects we desire.

C. C. C. Ferrocyanide of sodium is now largely made and used.
H. A. F.-The work is now in full operation.

D. C. J.-We would advise you not to look for the extreme prices; it is a dangerous proceeding.

B. W.-There are many substances which may be reckoned as explosives not coming under the Act.

TO OUR SUBSCRIBERS.-Owing to the fire at our printers' the almanac is not sufficiently advanced to issue with this number. It will be issued along with the index to Vol. I. as soon as ready.

We do not hold ourselves responsible for the opinions expressed by our correspondents.

THE INSTITUTE OF CHEMISTRY. To the Editor of the Chemical Trade Journal. Sir,—With regard to the correspondence now going on in your columns concerning the Institute of Chemistry, may I be permitted to make a few remarks from another standpoint? It appears to me that many of the unfortunate Fellows who are now deploring the absorption of their guineas by the Institute have really themselves to blame for the want of attention that they appear to have paid to the signs of the times in forming the unreasonable expectations that are so far from being realised. Your correspondent, "Menenius," for example, appears to think that in return for his subscription the Institute ought to protect him from the competition of those whose names are not followed by the mystical F.I.C. Now, sir, is this possible? I can quite imagine it to be within the limits of possibility that the Institute may eventually say in five or six hundred years, judging from their present rate of progress-succeed in restricting the right at present enjoyed by everybody to practise publicly as a consulting or analytical chemist; but I cannot conceive it possible in this age of progress and expansion that they will ever be so far able to interfere with the liberty of the subject as to dictate to the manufacturer in his choice of a chemist. The moral to me is a plain though perhaps a selfish one. I think that works' chemists had far better keep their guineas in their pockets, and leave the alluring Fellowship of the Institute, with its ennobling certificate of competency, to

those of their brethren who are enjoying or looking forward to a public practice, and who are possessed of a sufficient complement of confidence and guineas to go on indefinitely casting their bread upon the waters in the hope of seeing it after many days. I am, etc., COMMON Sense.

We have received several other letters upon this subject, but want of space compels us to hold them over until next week.-ED. C. T. J.

STEAM TRAPS.

To the Editor of the Chemical Trade Journal. Sir,-In your article in last week's journal you make a rather sweeping assertion that most of the existing steam traps in the market are nearly useless. To this statement as a steam trap maker I must demur, as I have seen and fitted many which acted perfectly, and were not " a standing dish for the fitting shop," as you have averred, When you say that there should be no valves or other impedimenta to prevent the condensed water flowing into the trap, you only express the construction of most of our "trap" makers, and it may be interesting to some of your readers to know that steam traps, constructed on similar principles to Klein's, of which you speak so highly, have long been made in this country by several firms. I enclose my card, but prefer to sign myself, A STEAM TRAP.

A CHEMICAL IMPOSTOR.

To the Editor of the Chemical Trade Journal. Sir, I desire, through the columns of your widely-circulated journal, to warn chemists against an impostor at present going the rounds. He is of medium height, fair hair, sallow complexion, face somewhat marked, slight moustache, generally seedy appearance, and distinct German accent. Age, 30 to 40.

He claims to be a Ph.D. Tells a most pitiable tale, and winds-up by showing pawnticket of gold watch or overcoat, or offering to sell books; or, again, requires money to go to Edinburgh or Hamburg, or perhaps to his wife and children in Perth or Aberdeen, or some other conveniently far-off place. Some of his aliases are Ross, Benedikt, Braun, or Brauns, etc.

To my knowledge he has fleeced many in Scotland and in the North of England; he visits works and city laboratories, with which he becomes conversant. Small chance has any deserving man who may follow him.-Yours, etc.,

F.I.C., F.C.S.

THE MANUFACTURE OF SULPHOCYANIDES.

DURING the past few years the sulphocyanides of certain metals have been largely employed in calico printing. As early as 1875, Messrs. Spence Bros., of Manchester, manufactured large quantities of sulphocyanide of ammonium from the residual products of gasworks, and later on when the ammonia became more valuable to them, the sulphocyanide was sold in the form of the calcium salt. The firm of John Nicholson and Sons, of Leeds, afterwards turned their attention to this manufacture, and placed large quantities of the crude article on the market, most of which was absorbed by the Clayton Aniline Co. and by Messrs. Higgin, Lloyd and Co., of Gaythorn. Having to compete with the purer article from the Continent, but little crude salt was at length manufactured, and it is to the present waste in England that is now going on that we desire to call attention.

The gas water produced by all the gas companies of the United Kingdom does not amount to less than one million tons annually. A ton of gas water contains on an average, about 14lb. of sulphocyanide of ammonium, so that the value at 8d. per lb. in the whole of the British ammonical liquor amounts to the respectable figure of £466,666 sterling per annum.

Our readers may say, perhaps, how is it that this loss has not been discovered before? It has been. In the year 1864, Mr. Peter Spence obtained letters patent for "Improvements in the manufacture of sulphocyanide of ammonium and other sulphocyanides," in which the mother liquor was treated with a solution of a mixture of sulphate of copper and protosulphate of iron in about equal quantities. A greyish white precipitate of cuprous sulphocyanide was precipitated which, after washing, was decomposed by the sulphide of the metal of which it was desirous to form the sulphocyanide. The treatment resulted in the formation of sulphide of copper, the basic metal combining with the sulphocyanogen.

Much of the sulphocyanide at present in the market goes to form a solution of the sulphocyanide of aluminium, a compound largely used in connection with artificial alizarine, and for this purpose the sulphocyanide of barium is preferred, as by mixing a solution of it with a solution of sulphate of alumina, an insoluble sulphate of barium is formed, which settles readily from the solution sulphocyanide of aluminium.

The following process for the production of sulphocyanide of barium may not be unworthy of the the attention of those manufacturers of sulphate of ammonia who desire to make something more out of their raw materials. The waste liquor from the sulphate of ammonia stills should be allowed to settle to get rid of suspended lime, the clear solution is then to be acidified with dilute sulphuric acid, and to it a solution of sulphate of copper and sulphate of iron is added in the proportion, 281b. of the former and 30lb. of the latter to each ton (220 gallons) of the waste liquor. The mixture must be well agitated and allowed to settle, and when sufficient of the magma has accumulated, it may be put through a filter-press and washed to free it from soluble impurities. Sulphide of barium must now be either made or procured. It may be easily produced by roasting the sulphate with small coal, but as it is an article now largely produced it will be found cheaper to purchase it. The insoluble sulphocyanide of copper is now kept agitated in a solution of barium sulphide until the sulphur has gone over to the copper and the sulphocyanogen to the barium. The black insoluble sulphide of copper is allowed to settle out, and the clear solution of sulphocyanide of barium is evaporated and allowed to crystallise. The methods here described may appear complicated, but in practice they are the simplest imaginable, and can be carried out with the most ordinary intelligence. There is only one point to watch -loss of copper. To avoid this, copper sulphate should never be added in excess to the crude liquor, a very simple test with ferrocyanide will avoid this, and it stands to reason also that the copper sulphide must not be wasted.

The copper sulphide is therefore to be collected and roasted in a furnace at a very gentle heat, when copper sulphate is formed mixed, however, with a little oxide. The roasted mass is lixivated with a weak solution of sulphuric acid, and used again and again in the round of precipitation. This process deserves the attention of all sulphate of ammonia manufacturers, as if the cost of manufacture is carefully kept down, there should be a profit at present prices equal to thirty shillings per ton of sulphate of ammonia.

In the production of a ton of sulphate of ammonia, it should be possible to produce nearly two hundredweights of sulphocyanide of barium. Some liquors are considerably weaker than this, but the figures cited above are the average of all liquors that have come under our notice.

Our Book Shelf.

A TEXT BOOK OF PAPERMAKING. By C. F. Cross and E. J. Bevan. London: E. and F. N. Spon.

THE authors state in their preface that their belief in the importance of a thorough scientific training for papermakers has dictated the style and purpose of the book," and if we follow them through the 240 pages which they have so pleasantly written, we shall find that they have treated their subject not only in a masterly manner, but have laid the technical side uppermost in a manner we have not been accustomed to in ordinary technical works. The authors have an advantage perhaps over most technical writers, inasmuch as they have both been practically engaged as chemists in large mills, and therefore have the whole subject at their fingers ends; moreover they have both done good work in investigating the properties of various kinds of cellulose, which may be found incorporated in Chapter I. "of their text book.

Chapters II. and III. are extremely interesting to chemists who have to make fibres their special study, and these, together with Chapters IV. and V., might be studied with advantage by every microscopist. In works of this kind it is so common to find woodcuts in the text that have been made to do duty several times over for other works, and possibly having their origin abroad, that it is a great treat to find something original, such as the sections of esparto grass and the microscopic characters of other fibres, which, having never seen before, we imagine have been drawn by the authors and cut specially for this work. Messrs Cross and

Bevan are photomicrographers of no mean order, and a plate of fibres from their manipulation forms the frontispiece to the book.

From Chapters VI. to XI. the various operations of the papermaker are minutely described, boiling, bleaching, beating, sizing, calendering, etc.; while Chapter XII. treats of the recovery of the waste soda-lye, which at one time was run by the papermakers into the nearest stream to poison the fishes and to make the water unfit for use to those below them. The remainder of the book is extremely interesting to those who essay to carry on their business in a scientific manner, and to look after the manufacture from a chemical standpoint.

In connection with the bleaching of pulp, a short account is given of the Hermite process of electric bleaching, which now only awaits a cheap source of electric energy for its final and complete development. The curious fact noted and recorded by the authors is, that the chlorine compounds set free during electrolysis from magnesium chloride is more active than the chlorine from bleaching powder in the proportion of 5 to 3. How this comes about is not explained, but perhaps the authors have this investigation in hand.

In order to bring up the information to the latest date, the American evaporator by multiple effect is described in the addenda. Some of these machines are now in course of erection in England for the evaporation of the waste soda lyes. The Porion evaporator, the Chapman, and Rôeckner evaporators are also described in the body of the work, so that the information is complete in this direction.

As a text book of papermaking we feel sure this work will result in a very large distribution, and we heartily recommend it to our readers, not only papermakers, but to all those who are interested in textile fibres.

A SYSTEMATIC HANDBOOK OF VOLUMETRIC ANALYSIS. Francis Sutton, F.I.C., F.C.S. Fifth edition. London: J. and A. Churchill.

SUTTON'S Volumetric Analysis is a work sufficiently well known to all chemists engaged in technology. Those who possess the earlier editions will now be pleased to find the treatise brought up to the present time by the insertion, in their proper places, of all methods of interest. Volumetric methods of analysis have increased to a very large extent during the past few years. It will be within the memory of most chemists, when volumetric methods were looked upon with a certain amount of misgiving, and this was certainly the feeling when Mr. Sutton was bold enough to put his first volume in print. How things have changed since then-we feel bound to say that with ordinary gravimetric methods, the routine work of a large chemical establishment could not be carried on, so that the importance of volumetric analysis may be seen at a glance by all those who have not even devoted much time or thought upon the subject.

The handbook before us is a work invaluable to all chemists engaged in any chemical industry whatsoever. In it may be found methods of analysis most minutely described, so that even the tyro may perform most of the operations. Chemical works in this country are not, as a rule, fitted up with a library and reading room, as most of them are abroad, any spare room is usually considered fit, in which to stow away the chemist; but if there is no shelf on which books of reference may be placed, we advise the chemist to find room for Mr. Sutton's book at home.

As we have said before, the work is brought up to date. In it may be found most of the applications of phenolphthalein for use in titrating carbonate and caustic alkalies, the valuation of acetates of lime by the phosphoric acid method, manganese estimation by Pattinson's method, and most of the work which Dr. Lunge has of late years contributed to volumetric analysis.

A very useful chapter, which may be studied with advantage by those engaged in water analysis is that on oxygen, and Messrs. Williams and Ramsay's modification of Schützenberger's method with hyposulphite may prove of considerable importance in determining the quality of a water. Manure chemists will find the chapter on phosphoric acid interesting; but strange to say, we do not find the word manures in the index.

A mass of new matter has been added to this present edition, so that the purchasers of former editions will find ample value in another outlay.

At page 460 we find a lengthy description of Thomas' gas apparatus, leading us on to a description of the more recent

Keiser's system, and to Hempel's method, all of which are very clearly explained.

The index might have been much more complete, perhaps this will be rectified in another edition, still the systematic manner in which the contents generally have been treated, will make up, no doubt, for any omissions in the index.

We feel bound to say that no chemist, using volumetric methods, would care to be without this work, if he once cast a glance over the contents of this, the fifth edition.

PEROXIDE OF HYDROGEN AS A MEANS OF BLEACHING WOOD.

BY DR. P. EBELL.

T the first glance it certainly appears strange that peroxide bleaching finer articles, although to a constantly increasing extent, should be proposed as a means for bleaching wood. There are, however, a few special cases in which the increase in value which is connected with the bleaching of the wood without entailing any structural alteration, is so important that both the cost of the peroxide, as well as that arising from the method itself, are hardly of any perceptible importance. Woods of 1 to 5 mm. in thickness can be bleached in a few days, while thicker planks require a longer action of the bleaching bath, inasmuch as it not only becomes a matter of importance that the bleaching fluid should be internally diffused throughout the wood in order that its action should be thoroughly efficacious, but also in order that the newly-formed soluble products of oxidisation should receive ample time to pass over into the fluid. A preliminary treatment of woods for the bleaching process, more especially as regards those already dried, has hitherto not led to any satisfactory results, as neither with dilute solutions of caustic or carbonated alkalis, nor by means of dilute acids can we remove the major portions of the inspissated colouring matters without doing injury to the body of the wood itself. For green wood, on the other hand, the method of systematic evaporisation would give good results, and would doubtless lead to a considerable saving of peroxide during the subsequent process of bleaching.

As regards the composition of the bleaching bath, it has been determined that the peroxide in an acid or neutral solution acts but very slowly on the colouring materials of the wood. On the other hand, however, alkaline, more especially ammoniacal, bleaching baths have been found to possess greater bleaching power. Corresponding with this, the bleaching baths were produced with 3 per cent. peroxide with ammonia solution (one litre of 3 per cent. peroxide and 20 grammes ammonia solution of o910 sp. gr.), and the dry wood was submerged in this fluid.

After a short time the alkaline reaction of the bleaching bath disappeared, giving place to an acid one. Apparently acid combinations arise from the process of oxidation, which have been neutralised by the ammonia present. By means of a subsequent addition of spirits of ammonia in small quantities, however, an alkaline reaction of the bleach baths rendered them permanently active.

The slabs of wood treated at the heat of 34° C. lose the colouring materials the soonest, however, the development of oxygen which takes place in the solution proves that a portion of the oxygen of the peroxide becomes under these circumstances, displaced without being utilised. The bleach bath in the cold only presents the above appearance to a moderate or even weak degree. The bleaching of the wood certainly proceeds more slowly, but the final effect or result was most decidedly more complete. In both cases the