Microscopical, 8.

Pharmaceutical, 8.

THURSDAY, 2nd.-Chemical 8. "On certain Bismuth Compounds," by M. M. Pattison Muir; " On Bismuthiferous Tesseral Pyrites," by Dr. William Ramsay; "On the Decomposition of Alcohol and its Homologues by the Joint Action of Aluminium and its Halogen Compounds," by Dr. Gladstone and Mr. Tribe; "Note on Incense Resin," by Dr. Stenhouse and Mr. Groves; "On the Occurrence of Native Calcium Chloride at Guy's Cliff, Warwickshire," by J. Spiller. "On Certain Sources of Error in the Ultimate Analysis of Organic Substances containing Nitrogen," by G. S. Johnson. Society of Arts, 8. Adjourned discussion on the paper by H. T. Wood, B.A., "On the Registration of Trade Marks."

FRIDAY, 3rd.-Geologists' Association, 8.

Society of Arts, 8. Special Lectures: "On Unhealthy Trades," by Dr. B. Richardson (Lecture I.),

TO CORRESPONDENTS.

P.H.-A correspondent suggests that you may find the information you require in "Traité Complet, Théorique et Pratique de la Fabrication du Sucre, Guide du Fabricant;" published at 20 francs. Eugéne Lacroix, Paris.

G. Evans.-Apply to the Secretary, Burlington House, Piccadilly, London, W.

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66

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wasteful loss to the manufacturer; and therefore the pre

VOL. XXXII. No. 836.

double advantage. This may not be apparent at first sight to the chief parties interested, for it has often happened in the course of my professional practice that the suggestions which I have offered for the mitigation of a nuisance have not been readily accepted by the manufacturer, although in the end they have been gratefully acknowledged. I can

MANUFACTURES,*

WITH ESPECIAL REFERENCE TO THE BEST PRACTICABLE MEANS OF ABATING THE SEVERAL NUISANCES THEREFROM.

By H. LETHEBY, M.B., M.A., &c.;

Professor of Chemistry in the College of the London Hospital; late
Medical Officer of Health and Public Analyst for the City
of London; and President of the Society of
Medical Officers of Health.

AMONGST the nuisances defined in the various Acts of Parliament, general and local, are those occasioned by the operations of trade and industry. Sections 27 and 28 of the Amended Nuisances' Removal and Diseases Prevention Acts (18 and 19 Vict., c. 121) express in a general way the character of these nuisances and the methods of procedure in cases of default. "If any candle-house, melting-house, melting-place, or soap-house, or any slaughter-house, or any building or place for boiling offal or blood, or for boiling, burning, or crushing bones, or any manufactory, building, or place used for any trade, business, process, or manufacture causing effluvia, be at any time certified to the local authority by any medical officer, or any two legally qualified medical practitioners, to be a nuisance or injurious to the health of the inhabitants of the neighbourhood, the local authority shall direct complaint to be made before any justice, &c., for the suppression or mitigation of the nuisance complained of ;" and by the Sanitary Act, 1866 (29 and 30 Vict., ch. 90, s. 18), a like power of initiating proceedings is given to any ten ratepayers of the place in which such nuisance exists, on a requisition in writing to the local authority. In case of such procedure, it is necessary, not only to show that the trade or business complained of "is a nuisance, or causes effluvia injurious to the health of the inhabitants of the neighbourhood," but also that the person complained against has not "used the best practicable means for abating such nuisance, or preventing or counteracting such effluvia."

It follows, therefore, that the supervision of such trades and manufactures, and the maintenance of them in such condition as that the best practicable means are constantly used to prevent the escape of offensive effluvia, forms one of the most important duties of the Medical Officer of Health; and as, in a professional capacity, I have had occasion frequently to visit and inspect most of the manufactories belonging to this category, I have thought that a brief account of my experience in the matter might be acceptable to my professional colleagues.

And here I ought to state that, on entering upon any nquiry of this description, it is proper to keep in mind the evident intentions of the Legislature, namely, the maintenance of the public health and comfort with due regard for the necessities of industry; for it will be observed that, although the preservation of the public health has been considered by Parliament of such paramount importance as to justify enactments containing enormous arbitrary powers, yet the exercise of those powers is always guarded with such provisos as will prevent abuse, and, thereby, unnecessary injury to trade. It is fortunate that, in most cases, the interests of the public and the manufacturer, although apparently conflicting, are really in accordance; for that which is injurious to the public is frequently a

* A Paper read before the Society of Medical Officers of Health. Communicated by the Author,

are concerned in such inquiries, that there need not be a feeling of antagonism in the matter; for if at any time it exists, it is either caused by a want of confidence in the skill and technical knowledge of the professional adviser of the local authority, or by an unjust and exaggerated view of the necessity for providing for the public health and comfort at all costs. This is manifestly in opposition to the spirit of the Acts of Parliament, so far as local authorities are concerned, for their duties are to see that the best practicable or available means are adopted to prevent the escape of noxious or offensive effluvia. If that fails to abate the nuisance complained of, the parties aggrieved have their remedy at law or in equity in one of Her Majesty's superior courts. On the other hand, as Mr. Keane observes, the manufacturer is bound to use the best practicable and available means to protect the public from annoyance or injury to health. It will not be enough to adopt such precautions only as are used in the place or district among persons carrying on the same business or manufacture, if it has been ascertained that there are better which are available; and in interpreting the words available and practicable, it is probable that the magistrates will pay more attention tò scientific than pecuniary difficulties. It is of great importance, therefore, that the opinions of the Medical Officer of Health should be well founded, and his recommendations free from reasonable objections, for it must not be forgotten that the manufacturer, if he thinks himself aggrieved, has the right and power of appeal from the justices to a superior court, where the knowledge and judgment of the medical officer will be severely tested.

But, besides the nuisances which are caused by manufacturing operations, there are others which are more or less incidental to them, as well as to other branches of trade and industry. "Any accumulation or deposit which is a nuisance or injurious to health; or any pool, ditch, gutter, or watercourse, so foul as to be a nuisance, or injurious to health" (18 and 19 Vict., c. 121, s. 8); or " any factory, workshop, or workplace, not already under the operation of any general Act for the regulation of factories, or bakehouses, not kept in a cleanly state, or not ventilated in such a manner as to render harmless, as far as practicable, any gases, vapours, dust, or other impurities generated in the course of the work carried on therein, that are a nuisance or injurious to health;" and "any fireplace or furnace which does not, as far as practicable, consume the smoke arising from the combustible material used in such fireplace or furnace;" and "any chimney (not being the chimney of a private dwelling-house) sending forth black smoke in such quantity as to be a nuisance "(29 and 30 Vict., c. 90, s. 19)—all of which are under the supervision of the Medical Officer of Health, with a view to legal proceedings in case of default.

Looking at the individual peculiarities of these nuisances, it is evident they may be conveniently classified under three heads, namely:

(1). Those which are caused by the escape of noxious or offensive effluvia, as gases and vapours.

(2). Those which are produced by smoke, dust, or other mechanical impurities.

(3). Those which are occasioned by the discharge of noxious or offensive matters into gutters, ditches, or water

264

CHEMICAL NEWS, Dec. 3, 1875.

of high pressure steam set in the solution.

Foremost of those operations which cause offence by the escape of sulphuretted hydrogen into the atmosphere is the manufacture of sulphate of ammonia from gas liquor. This liquor is produced in great quantity at the gasworks-varying from 10 to 40 gallons per ton of coals, according to the strength of the liquor and the perfection of the processes for removing ammonia from gas. The strength of the liquor is estimated and expressed by its gravity in degrees of Twaddell, or by the number of ounces of strong sulphuric acid (sp. gr., 1850) required to saturate a gallon of it. This varies from 5 or 6 ounces per gallon to 25 ounces, and, according to my experience, the proportion of sulphuretted hydrogen contained in it ranges from 230 grains, or rather less than one-third of a cubic foot per gallon, to rather more than 1250 grains, or nearly 2 cubic feet per gallon; so that the liquor is exceedingly offensive from the quantity of sulphuretted hydrogen contained in it; and therefore it is necessary to store it in air-tight tanks, and to transport it from place to place in air-tight vessels-as barrels or tank-barges, or tank-trucks. It is proper also that the orifices which give exit to the air at the time of filling the tanks should be guarded with a box or small barrel containing hydrated oxide of iron, which absorbs the sulphuretted hydrogen, producing sulphide of iron, which is subsequently revived by the action

of the air.

In some cases

The methods of treating this liquor with sulphuric acid so as to produce sulphate of ammonia have differed at different times and places. In my early experience, even in this metropolis, the process was to neutralise the liquor with brown acid of sp. gr. 1'720, and to convey the evolved gases into a furnace fire, as their escape into the air would be dangerous to the workmen; and the saturated liquor still reeking with sulphuretted hydrogen was evaporated in open lead troughs over open fires. The nuisance arising from these operations was absolutely unbearable; and as people got to be more and more sensitive of annoyance, the old process was discontinued. At the present time the practice is to evaporate or distil the liquor from closed boilers or chambers, and to convey the volatile products-ammonia, carbonic acid, and sulphuretted hydrogen-into a closed chamber, or saturator, containing weak sulphuric acid, there being a contrivance for the escape of carbonic acid and sulphuretted hydrogen, and the conveyance of them to a furnace fire. the liquor is distilled from boilers set over a common fire; but, as this is liable to flushes and irregularity in working, it is objectionable, and has given place to the process of distilling by means of a steam coil set in the boiler, by which steam at from 20 to 30 lbs. pressure is blown into the liquor. But the best contrivance of all is that known as Coffey's still, which consists of a vertical chamber from 20 to 25 feet in height, having a series of transverse septa which alternately leave an opening at their ends. In this way, with about sixty of such septa, a superficial area of about 1000 square feet of evaporating surface may be obtained. The liquor is delivered in a constant and graduated stream at the top of the chamber, and as it Hows backwards and forwards in a descending current over the transverse septa, it meets with an ascending blast of steam which is let into the bottom of the chamber at a pressure of from 15 to 30 lbs. In this way the volatile constituents of the liquor are carried over to the saturator, where the ammonia is arrested by sulphuric acid, and the exhausted liquor flows out in a continuous stream from the bottom of the chamber. The saturator is generally an air-tight leaden vessel, about 4 or 5 feet square and 3 or 4 feet deep, containing a charge of diluted sulphuric acid equal parts of chamber acid (1600) and water. When the acid is saturated with ammonia, which is known by test-papers, steam alone is blown into it from the still for about half on hour to displace all traces of sulphuretted hydrogen, and the solution is drawn off into open pans or

Another kind of saturator occasionally in use is a leaden vessel divided into two compartments by a diaphragm or curtain, which descends below the liquid to within about 18 inches of the bottom. One of these compartments is closed air-tight and receives the volatile products of the still, where they meet with a graduated stream of brown acid (sp. gr. 1720), which continually neutralises them, and forms crystals of sulphate of ammonia, which are constantly ladled out of the open compartment. The apparatus is ingenious, and saves much labour and time in evaporation, as the acid is used in its undiluted condition; but it is not so certain or satisfactory in its action as the closed saturator before described.

In both cases the uncondensed gases-sulphuretted hydrogen and carbonic acid-with much steam, are conveyed from the saturator through a 4-inch pipe to the furnace fire, where the sulphuretted hydrogen is burnt. It is necessary, however, that the sulphuretted hydrogen should be deprived of its moisture before it reaches the fire, or it will extinguish it; and this is effected by throwing the pipe into coils, or otherwise cooling it. The precautions, therefore, to be taken in the conduct of this business

pressure steam.

and the complete expulsion of sulphuretted hydrogen from (3). The saturation of the ammonia in close vessels, the saturated solution before it is drawn off for evaporation.

(4). The condensation of moisture from the sulphuretted hydrogen evolved from the saturator; and the conveyance of the cold dry gas to the furnace fire where it is to be completely burnt.

still with cream of lime, so as to recover the residual (5). The treatment of the exhausted liquor from the ammonia by a second distillation; or, if the process be in operation at a gas works, the use of the residual ammonia as an absorbent in the purification of gas.

tightness of all parts of the apparatus. (6). The observance of the greatest care as regards the

Another operation which demands care in its management is the distillation of coal-tar for the various products derivable from it. There are two kinds of tar from coal, according as the temperature of distillation is high or low, and according to the richness of the coal in hydrocarbon. One is ordinary coal-tar, and the other is the tar from which paraffin oils are obtained. The tar produced from common coals at a high temperature (common coal-tar) is always heavier than water (sp. gr., 1120 to 1'150); it dries freely in the air by oxidation; it contains hydrocarbons with such an excess of carbon that they cannot be burnt in a common lamp; it is almost entirely destroyed by strong oil of vitriol; it contains much sulphur, and its percentage composition is about 86 carbon, 7 hydrogen, 65 oxygen, and o‘5 sulphur. Whereas the tar produced from cannel coal at a low temperature is lighter than water (sp. gr., about o'900); it will not oxidate, or dry in the air, it contains hydrocarbons of the paraffin series which are comparatively poor in carbon, and which can be burnt in a lamp; it is not much acted on by oil of vitriol; it contains little or no sulphur; and its percentage composition is about 84 carbon, 12 hydrogen, and 4 oxygen. Both of these tars are the subjects of technical manipulation, and if not properly managed are the cause of nuisance, as are also the processes used in their primary production. In dealing with ordinary coal-tar, it is proper that it should be stored and carried in air-tight tanks, and left covered with a little water. The delivery of it into tank-barges or tank-trucks, and from them into the tanks of the works,

attained the maximum possible for its size. In order to proceed slowly against a fresh breeze, with the sources of mechanical power at present available, the volume of the balloon must be three and a half times larger than that of the largest ship of the line. This demands of the tissue with which the balloon is to be constructed a degree of strength scarcely possible. In fact the expectations of the inventors did not go beyond the hope of steering the balloon when the air is tranquil. If the screws or paddle-wheels are enlarged they must also be made thicker and stronger in order to preserve the necessary firmness. "We can only work sparingly with slowly-moving propellers of large surface, and to produce these of the requisite size without burdening the balloon too much will constitute one of the greatest practical difficulties."

With this sentence Helmholtz concludes his memoir, and the prospects to which he points fall very far short of the enthusiastic phophecies of such as are guided by their wishes rather than by sober scientific considerations. The problem of steering balloons turns on three conditions-the production of balloons of the lowest specific gravity; the construction of propellers, light, but capable of resistance; and of sources of power at once light and capable of performing a high duty. In how far chemistry has prepared the way towards the fulfilment of the last condition, e. g., by means of aluminium, the future must decide. The first condition she has accomplished ninety years ago, by means of hydrogen, as is now fully recognised.

Upon the consideration of hydrogen and oxygen should follow an account of the industrial applications of water. These, however, are so many-sided-not to say omnipresent that they escape our reach. The most important will be considered in especial chapters.

The elements oxygen and hydrogen form, however, as is well known, a second compound, peroxide of hydrogen, H2O2, which has latterly begun to acquire a certain industrial importance.

THE following candidates were elected members of the Society:-Professor Osborne Reynolds, M.A.; Professor H. J. Smith, M.A., LL.D.; Professor R. B. Clifton, M.A., F.R.S.; C. Busk; J. Thomson; J. W. W. Waghorn; W. Esson, M.A., F.R.S.; F. W. Bayly; and Professor R. W. Emerson MacIvor.

Professor GUTHRIE briefly described Dr. Kerr's recent experiments to show that glass, resin, and certain other substances exhibit a depolarising effect when under the influence of powerful electrical tension, and he exhibited the arrangement of apparatus employed in the research. He also showed certain experiments connected with the investigation.

Dr. GUTHRIE then made a communication on "Stationary Liquid Waves," in continuation of that which he made to the Society in June last. If water in a cylindrical vessel not less than 9 inches in diameter be agitated by depressing and elevating a flat circular disc on its surface

CHEMICAL NEWS, Dec. 3, 1875.

at the centre, a form of oscillation is set up which the author terms "binodal." He finds that these fundamental undulations in an infinitely deep circular vessel are isochronous with those of a pendulum whose length is equal to the radius of the vessel; and further, a fact which is extremely interesting, that the motions of the pendulum and water keep together throughout their entire paths. An arrangement was exhibited for experimentally demonstrating these facts. To the upper end of a short pendulum with a heavy adjustable bob is attached a cardboard sector, in the plane of vibration of the pendulum. A silk thread attached to the edge of this sector carries a small paraffin disc, which rests at the centre of the surface of the water contained in a cylindrical vessel. The pendulumlength is adjusted until the motion of the disc is isochronous with that of the water when the two are not in contact. Two other forms of motion may be produced in cylindrical vessels, namely (1), by alternately compressing and extending opposite ends of a diameter, as in the motion of a bell (this gives two diametral nodes, at right angles to each other); and (2) by rocking the vessel, which gives a single diametral node. Each of these has its own period of vibration, the last being the slowest. They may be super-imposed on each other, and a rotation of the water, however great, does not interfere with their formation. In rectangular troughs a binodal and a mononodal wave-system may be established. The former is induced by raising and depressing a wooden lath at the middle of the surface, and the latter by tilting. Binodal vibration in a circular trough may be compared with a vibrating pair of triangular laths, and in rectangular troughs to the balancing of two rectangular laths. In this latter case, the nodes are at one-fourth of the trough's length from each end. Some discrepancies are met with when we compare times of vibration in rectangular troughs of various lengths, and these are due to a scraping action which takes place against the sides of the vessel. The result of the experiments on binodal motion in rectangular vessels is to show that the undulations are isochronous with the oscillations of a pendulum whose length is times that of the trough. The chief points in connection with this subject to which the author referred as still requiring explanation are:(1). Why are the motions pendular? (2). How is it that, in circular binodal motion, the times are identical with that of a pendulum of the given length? And (3), What is the mathematical connection between the individual motion of each particle and that of the mass.

π

Mr. LODGE thought that valuable results might be obtained by treating the mass of moving water as a pendulum, with two bobs oscillating about the node. This might be specially useful with small oscillations, when the surface is practically plane.

NEWCASTLE-UPON-TYNE CHEMICAL SOCIETY. General Meeting, October 28th, 1875.

JOHN PATTINSON, President, in the Chair.

THE minutes of the last general meeting were read and confirmed. The Committee's report and Treasurer's statement were presented.

PRESIDENT'S ADDRESS. Gentlemen, I have to thank you for the great honour you have again conferred upon me in electing me to be your President for the ensuing session.

In making the customary review of the work accomplished by our Society in the past year, it will be found, I think, that this will bear comparision with the work of most of the previous years of our existence as a society, not only as regards the number of papers read, but also as regards the importance and value of these papers.

Mr. John Morrison gave us a very able and interesting