four feet, with great damage to property. In some way or other it has become imperative to dispose otherwise of the sewage, apart altogether from the agricultural part of the question.

The Commissioners state that in about thirty towns in England means are now taken for dealing with sewage before its discharge into rivers and streams. In most cases the chief aim has been to separate the solid matter by rest and mechanical means, rather than by chemical agency. Mechanical means often fail; sand-filters become clogged and inoperative immediately. At Rugby, after a trial of three years, they have been discontinued. Upward and downward filtration have been tried at Birmingham with indifferent success. The simplest plan scems the best, and that adopted at Worksop is a good one. The first cost for a population of 7,000 was only 5307., and the current expenses are merely one-halfpenny per head yearly. The works consist of a series of parallel open trenches, having a section area ten times as large as that of the outlet sewer; the sewage circulates, therefore, very slowly, and the greater part of the solid matter is deposited. Moveable hurdle or wicker-work strainers are placed across the trenches for intercepting the lighter portions; lime is used to deodorise when necessary. If desirable such trenches can be covered. At Uxbridge lump charcoal, and at Bilston furnace clinkers, are used for straining the sewage. At Coventry and Chelmsford the deposited matter is taken from the tanks, is mixed with town sweepings, or with tan and other dry refuse, and find a ready sale; it is not, however, remunerative. At Carlisle Mr. McDougal has taken a lease of the sewage, and deodorises it with his crude carbolic acid, and then applies it to land.

In certain cases, when the thinner part of the sewage can be applied to grass land in very large quantities, and in an economical manner by gravitation, the results have been extremely favourable. It does not appear to be so well adapted for arable land; a small quantity of grass will take a very large quantity of sewage, and deodorises it so rapidly that no odour can be perceived; there is, however, a limit to this.

In some cases towns have hired meadows for the sole purpose of spreading the thin part of the sewage over them, and thus getting rid of it; in other cases, after the subsidence of the thicker part, the fluid is allowed to flow into streams.

A "dry method" has been used for almost two years by the "Patent Eureka Sanitary and Manure Company," which is somewhat similar in principle to that employed at Ferozepore and other towns in India. About 180 cottages at Hyde, in Cheshire, have been under the system for two years. Instead of the old ashpit and cesspool, a barrel or tub is used, in which all the ashes and the refuse of the cottage are placed. Under the seat is a drawer, which is sprinkled with a deodorant, said to be so efficient that even when the drawer is full there is no smell. All the urine of the cottage is put into this drawer, but no slops. At certain intervals (about every two months) a van visits each cottage, the drawer is removed, fitted with a lid, replaced by an empty drawer, and taken to the works; here all the sewage is put into a large tank, treated chemically to prevent the escape of the ammonia, and then steam heat is applied in proper boilers, so that the bulk is reduced to less than one-seventh. It is then mixed with very fine calcined ashes, and forms a portable, and, it is said, profitable manure.

The whole town of Hyde is about to be treated in the same way, and, if it be true that decomposition of sewage is so entirely prevented, and that the result is profitable, we shall see a large extension of this method in our small towns. It is of course necessary to be cautious in dealing with the statements of those who have projected and are carrying out this plan, but it is only fair to state that the Inspectors of Nuisances at Hyde have reported (p. 91) very favourably indeed of it.

It does not appear that the application of the sewerage to land, though it sometimes causes a nuisance, has been productive of disease; probably the

On the Craigentinny meadows, near Edinburgh, where the average value of a grass crop is from 207. to 30l. per annum, the sewage derived from a population of 80,000 is spread over only 325 imperial acres.

+ Second Report of the House of Commons Committee, p. 18, et seq.

greedy absorption by the ground is so great, as to do away with much risk from this source, but certainly the point requires to be carefully watched.

Composition of Sewage.-A good many analyses of sewage water are given in these various publications. I have selected four from Mr. Way's evidence (Second Report of Commission, p. 69, et seq.), as samples of the usual composition.

List of Deodorants employed.-The Commission give a list of deodorants, and an account of their action, which it may be useful to condense.

1. Quicklime and water added till a deposit occurs, leaving a clear fluid above. This is chiefly caused by the lime forming insoluble salts, by union with carbonic and phosphoric acids, and mechanically carrying down the suspended matters. The sulphuretted hydrogen forms sulphuret of calcium, which remains in the supernatant fluid. The ammonia is set free. The potash salts remain in the liquid. Five-sixths of the phosphoric acid are in the precipitate. No organic matter is precipitated except mechanically. The solid deposit has little value as manure. The lime delays, but does not prevent the subsequent decomposition of the animal vegetable matters, and as the sulphuret of calcium easily decomposes, sulphuretted hydrogen is very liable to be again set free from the clear fluid.

The process, though simple and cheap, is by no means perfect. The addition of charcoal to the lime does not materially modify the result.

From 15 to 16 grains per gallon of quicklime are enough for 1 gallon of sewage, or 20 cwt. per million gallons.

2. Cheap salts of alumina, and thin lime, or zinc and charcoal (Stothert's process).

The alumina precipitated by the lime forms a very bulky precipitate, well suited to the entanglement of suspended matters. The clearance of the sewage is more perfect than with lime alone, but otherwise the process and the objections are the same, and the cost is greater. The whole of the phosphoric acid is precipitated as phosphate of alumina. To a gallon of sewage were added 734 grains of sulphate of alumina, 3 grains of sulphate of zinc, 73) grains of charcoal, 16 grains of quicklime.

3. Superphosphate of magnesia, and lime water (Blyth's patent). The idea was to add a substance, which in addition to deodorizing, might be useful as a manure, and it was thought that a double phosphate of magnesia and ammonia would be thrown down; but this salt is sufficiently soluble in water, especially when it contains chloride of sodium, to render this expectation incorrect. This method has been practically found to be useless, and to be more costly than any other plan.

4. Sulphites of lime and magnesia, mixed with products from tar (carbolic acid, &c.) The fermentation is supposed to be arrested by both classes of substances. The sulphites destroy sulphuretted hydrogen; their action, however, is transient, and they themselves are very liable to change; the tarry products have a comparatively limited action; they have some influence, but they rather mask the odour, than absolutely prevent decomposition. The sewage is not precipitated by this process. This is a lime process with improvements, but with greater expense.

X

5. Perchloride of iron. When this salt is added to sewage, a precipitate of peroxide of iron is caused by the carbonate of ammonia, which forms so rapidly in sewage, and carries with it all the suspended matters of the sewage. A clear fluid remains above. The sulphuretted hydrogen falls in the precipitate as sulphuret of iron.

Both precipitate and supernatant liquid are free from odour.

This is the "best practicable precipitant" of sewage. It has been tried at Croydon and Coventry. From 14 to 29 grains per gallon of sewage are necessary for London sewage; for Croydon sewage from 5 to 15 grains were necessary.

The perchlorides of iron can be manufactured by dissolving peroxide of iron in hydrochloric acid; the different iron ores, refuse oxide of iron, from sulphuric acid works, iron rust in foundries, &c. Another plan is to take equivalent proportions of common salt, sulphuric acid, iron rust, and water, so that chlorine, when disengaged, shall combine with the iron. A hard, yellowish material, not very deliquescent substance, containing 26 per cent. of perchloride of iron, is formed, which can be transported to any distance. The price, "if made in this way, is 27. 78. per ton (cost of labour not included).

The above is an abstract of the Commissioners' conclusions and Mr. Way's statements. The perchloride of iron is ranked as highly as it formerly was by Hofmann and Frankland. M'Dougall's powder and fluid (carbolic acid) are, however, probably underrated.

SPREAD OF THE SPECIFIC DISEASES.

The question in etiology which is perhaps of all others the most immediately interesting, viz., the conditions of origin, and spread of the specific diseases, has been discussed by Dr. Murchison in a work which it is not too much to say is one of the best, if not the very best, which has ever been published on the Continued Fevers* of this country. Dr. Murchison is one of the strongest advocates for the spontaneous origin of typhus and typhoid, or enteric, or, as he terms it, pythogenic fever, and his work was therefore looked to with the greatest interest, to see what positive evidence he could bring in support of his views. A brief statement of his argument may be useful to those who cannot procure the work.

Typhus. That the spread of typhus is intimately connected with overcrowding, and can be very easily arrested by free ventilation, has long been known. Dr. Murchison, in the first instance, proves that typhus is contagious, a fact few will now dispute; then that it is communicated through the cutaneous and pulmonary exhalations, and inhaled or perhaps swallowed; that it is transmitted to a small distance only through the air (perhaps from the ease with which it is oxidized); that it can be communicated by fomites in clothes (a fact of which the writer of this Report has seen a striking and apparently quite certain instance); that if the poison be concentrated, exposure for a few minutes only may produce the disease; that its latent period is from a few hours to about twelve days, but is perhaps usually about nine days, and that it is probably most contagious from the end of the first week to convalescence, viz., during the time when the odour from the skin is strongest. He also notices the statements that the poison is lighter than atmospheric air, and ascends (a difficult thing to prove), and that it is destroyed by a heat of 204° Fahrenheit (Henry). Having discussed these points with great care and acuteness, Dr. Murchison argues that typhus can spontaneously originate from great overcrowding and deficient ventilation, and he proceeds to cite instances which he has collected, and instances he has observed. Of the former he cites five instances, in all of which there was prevalence of the disease under such conditions of overcrowding, without decided evidence of importation. All these cases, however, are weak as respects the negative evidence, of the absence of importation.

The groups of cases observed by himself are three in number; in all he examined for a source of contagion, but could find none; in all the conditions

A Treatise on the Continued Fevers of Great Britain. By Charles Murchison, M.D. London: 1862. Pp. 638.

of overcrowding and of a foetid and putrid air existed in the highest intensity. These instances are certainly the strongest which have ever been brought forward; but it must be remembered that they are very few in number, and that in London the difficulty of tracing the introduction of a contagion is extreme. Dozens, nay, even hundreds of such cases, with perfect negative evidence as to non-importation, would be necessary to carry conviction on this point. It seems impossible to deny that Dr. Murchison's cases are forcible; that they are not convincing will be perhaps a general opinion. Reference is next made to outbreaks of jail, ship, and military typhus; but it must be remembered that in jails, till the time of Howard, jail fever was never absent, and that in the case of ships there is, again, an extreme difficulty in excluding importation. In the cases of military fever, the outbreak in the Crimea is alluded to, and it is stated that there is no evidence "that it was imported," but typhus was prevailing among the Turks during the whole period of the war, and there must have been plenty of poison carried by the Turkish corps serving with the Allies. No stress can be laid on this case. In the other instances referred to, the typhus of Dantzic, in 1813, was merely an offshoot of the typhus which prevailed in all the armies in 1812 (and, indeed, more or less in all the Napoleonic wars), and it can hardly be cited as an instance of spontaneous origin; and this may be said, also, of the typhus at Torgau, in

1813.

On the whole, while it is undoubted that typhus spreads and devastates only in overcrowded and ill-ventilated places, we cannot but believe that much more evidence is necessary to prove its origin in that way. The accessory conditions which assist its spread are depicted very truly and vigorously by Dr. Murchison.

Typhoid or Enteric Fever-Dr. Murchison's evidence of the spontaneous origin of typhoid fever from foecal decomposition is stronger than in the analogous case of typhus. He has assembled thirteen cases in which outbreaks of typhoid fever occurred in connection with sewage exhalations; if any doubt had previously existed on this point, this series of crucial instances would have removed it. Subsequently Dr. Murchis u proceeds to argue the question whether any kind of focal decomposition will produce the disease, or whether, as strongly urged by Dr. William Budd, the evacuations of patients ill with typhoid fever must have passed into the sewers or cesspools. He points out, first, that in some cases, when typhoid fever arose from drains, there is no evidence of the entrance of typhoid stools; second, that there are cases of outbreaks "from bad drainage," where it is impossible to conceive that the poison was introduced into the drain, and he cites the cases of the Peckham Police Station, Westminster, Clapham, and Colchester (in which last place, especially, "every possibility of importation appears to have been excluded"), and country places known to him, or to persons furnishing information to him.

He then refers to the negative instances of persons not contracting typhoid fever when exposed to different animal, and even sewer vapours, and refers to the quoted instances given by Parent Du Chatelet and Guy, of the nonprevalence of typhoid fever among sewer and night-men. He points out the imperfections of both these inquiries, which he justly regards as of small value, and then refers to observations of Peacock and himself, that "enteric fever is not uncommon among the workers in sewers."

He then shows that many of the statements formerly made cannot be received, in consequence of the distinction between typhus and typhoid fever not being known.

Such is the sketch of the argument, which is well worked out, but which appears to us deficient in one or two points. Dr. Murchison does not allude to cases in which small villages, unsewered, and apparently the very places of election for typhoid fever, have for years remained free, although at some time all requisite conditions of temperature, humidity, &c., must have been present. Then, at last, a person enters who has typhoid fever, and from this source the hitherto healthy village becomes infected. Again, he seems to pass by much too lightly the positive evidence that the typhoid stools will excite the fever, a fact of which there is no doubt, and in all his negative instances he does not refer to the very great difficulty in this case, as in the case of typhus, of

proving a negative. On the whole, it seems very doubtful whether the profession will consider his case to be made out. Certainly it must be conceded that more evidence, and a stricter inquiry, are still necessary.

Dr. Murchison alludes to and admits the occasional propagation of typhoid fever by drinking water. This appears to us one of the most important points lately discovered in etiology. Riecke* quoted, more than twelve years ago, two or three instances of this kind, and a considerable number of cases are now on record.

Although many of these cases are not very perfectly recorded, it has appeared to the writer that these points can be tolerably clearly made out-first, that a much larger number of persons are attacked than when the disease is communicated, as it usually is, through the air; and secondly, that the period of incubation is much shortened, and that the succeeding fever is more severe. Probably in this way a larger amount of the poison is swallowed, and either absorbed into the blood, or what appears more likely, applied to a greater extent of the agminated glands than when the poison is drawn in with the air, and then swallowed. The great effect of impure water in this way does, indeed, tend to show that the changes in Peyer's patches may be the very first conditions which precede the general fever, and possibly even cause it. Whatever opinions may be finally come to, every year's experience is bringing out more clearly the paramount importance of properly disposing of the typhoid stools; they should on no account pass into sewers or cesspools, but should be mixed with disinfectants, and then buried.

Relapsing Fever.-Dr. Murchison fully admits the contagion of relapsing fever, but also believes it can be spontaneously generated, and that its grand causes are, as in the case of typhus, destitution and overcrowding. There can be no doubt of the intimate connection between starvation and relapsing fever, but it must be confessed that the production of relapsing fever is very obscure.

On the whole, this very able book seems to leave the question of the spontaneous origin of these specific diseases very much where it was; if anything, Dr. Murchison's instances and arguments in favour of origin, de novo, are less complete than might have been anticipated.

Straw Measles.-A very extraordinary statement has been made by an American physician, Dr. Salisbury, that an attack of a disease closely resembling measles, and attended with catarrhal symptoms, and with red blotches on the skin, was produced in the camp at Newark by apparently the dust of decayed straw, containing fungi in abundance.

Dr. Salisbury inoculated himself and his wife with the spores and cells of the fungi of wheat straw, and produced in both a disease which he states he could not distinguish from measles; the same result was given in thirteen other cases. The disease appears in from twenty-four to ninety-six hours after the inhalation of the fungi. It is to be hoped that so easy an experiment will soon be repeated.

STATISTICAL INQUIRIES ESPECIALLY CONNECTED WITH HYGIENE.

It is impossible to give any analysis of the vast number of statistical papers which are published every year. Two essays only, published in 1862, may be mentioned here, first, the Vital Statistics of Sweden, which show the condition of a northern population thinly scattered over the country, and not congregated into towns, and second, an Inquiry into the Action of Malaria on the Duration of Life, which, both by its method and its exactness, is an important essay.

Vital Statistics of Sweden.-These are drawn, from records kept since 1749, with great care. The following are merely a few of the points noted :—

Der Kriegs-und Friedens-Typhus in den Arméen. Von D. C. F. Riecke. Nordhausen, 1850. Pp. 44.

+ American Journal of Medical Science, and American Medical Times. September 6th, 1862. Pp. 133.

Hendriks, in the Statistical Journal, June 1862. Vol. xxv. Pp. 111.