carried off by the artificial under drains, while its organic constituents are subjected to oxidation by the agency of microorganisms producing the phenomenon known as "nitrification." The solid parts left in the soil are also attached, and gradually succumb to the influence of hydration and oxidation; but there is a limit to this process, and should the land become overcharged or choked with solid matters, which often occurs on sewage farms, oxidation will not proceed, and an intolerable nuisance ensues.

To prevent this the separation of the solids from the fluids of sewage is essential, and after this the effluent may be disposed of with entire immunity by a process of irrigation; or, in the absence of special objections, the effluent may be discharged into a river or other water area having sufficient volume or flow to oxidize the organic matters which are held in solution. This, however, applies only to sewage, whether mixed with rain water or not, that has been so dealt with by screening, subsidence, precipitation or otherwise, that the solid parts are removed from the liquid parts.

If our boasted scientific knowledge is worth anything, it should enable us to separate the fluid from the solid parts of excretal sewage, and to convert the latter into a good practical manure, while the fluids may be discharged into the soil, or into some water-course, in an innocuous condition.

Some three or four years ago Mr. C. T. Kingzett, the distinguished London chemist, suggested that a small portable apparatus might be supplied to each house, provided with a strainer, whereby the water of crude sewage would be separated from the solid parts; and the receivers could, by a properly organized system, be collected as often as necessary, and a clean one left in the place of the one removed. Such an apparatus, it scarce need be said, should be as simple and as economical as possible, consistently with preventing nuisance or danger to public health; and I claim for a device which I have lately introduced, that it is at once the most simple, the most effective and the most economical that has yet been proposed for the purpose. The method consists of a process and apparatus by which the solid matters of household refuse are effectively separated from the water of crude sewage by mechanical straining, subsidence and precipitation,

whereby a large proportion of the suspended matters are detained in a hermetically closed receptacle, which when full can be removed and replaced with an empty one by a common laborer, while the liquid parts are continuously delivered in such a condition of purity, that they may be used to irrigate the soil with advantage, and without any danger of choking its pores; or the effluent from the precipitating tank may be further purified by filtration through iron to such an extent that it can be discharged into any drain, sewer, cess-pit, river or stream with entire immunity. The apparatus is illustrated in the following diagram :

Fig. 5 represents a vertical section of the apparatus with all its parts intact, except the filter, which is omitted, as it is rarely to be used. A represents the receiving vessel or "receiver;" B, the settling or "precipitating tank ;" D, the outer cylinder of the "strainers;" E, the inner perforated "strainer;" FF, the soil pipe connected with the strainer E above and below; G, the collar which connects the soil pipe with the receiver; H, the box or holder for the precipitating reagent ; I, pipe connecting the receiver and precipitating tank for the purpose of drawing down the water to prevent slopping when the receiver A is detached at the cellar G to be removed. When detached the opening at G is closed with a close-fitting cap.

The operation of the apparatus is as follows: All such matters as are generally discharged into the soil pipes of houses are conveyed into the "receptacle," which is removably connected with the soil or drain pipe. The coarser, undissolved matters, such as foreign bodies, ordure, and paper not yet dissolved, which the trap of the soil pipe has allowed to pass, sink by gravity to the bottom of the receptacle, while the matters that are more or less dissolved in water find their way along with the supernatant liquid of the sewage through the meshes of the strainer, and from thence by a connecting pipe D into the precipitating tank.

The precipitating tank receives the overflow from the receptacle" which has passed through the strainer. This tank is provided with an automatic device for discharging a certain quantity of chemical precipitants into its contents. The supernatant liquid in the precipitating tank, already quite pure, is discharged through the pipe h, which, when the effluvent is to be disposed of by subsurface irrigation, is converted into a siphon simply, by extending this pipe downward, on the inside of the tank, to a point near the bottom. In this way the flush through the subsurface irrigation pipes becomes rapid and continuous until the tank is emptied.

The receivers, containing the solid parts of excretal matters, are to be collected, when full, by a properly organized system, and clean ones left in their places. These receivers should be taken directly to the usine or compost factory, where their contents may be worked up, with other sub

stances, it may be, into an innocuous and valuable manure powder ready for immediate application to the soil. The utilization of the solid excreta is not, however (and this is a very important matter to public bodies which have to do with the disposal of sewage), confined in any sense to its employment as a manure, or as a source of ammonia and certain salts. It may be pressed, air-dried, and employed as ordinary fuel for use in boilers or other furnaces. Further, it may be ground up with clay and lime, and converted into brick or cement after the process devised by the late General Scott, of England; or, again, it may be admixed with other materials, such as are ordinarily employed, and converted into a material for use in the construction of sidewalks, foundations of buildings, etc.-Journal American Medical Association.

THE DISINFECTION OF EXCRETA.*

By GEORGE M. STERNBERG, M.D., Lieutenant-Colonel and Surgeon U. S. A.

THE Committee on Disinfectants appointed by the Ameri can Public Health Association in 1884, in its final report, submitted in 1887, gives the following general directions:

Disinfection of Excreta, etc.-The infectious character of the dejections of patients suffering from cholera and from typhoid-fever is well established, and this is true of mild cases and of the earliest stages of these diseases as well as of severe and fatal cases. It is probable that epidemic dysentery, tuberculosis, and perhaps diphtheria, yellow-fever, scarletfever, and typhus-fever, may also be transmitted by means of the alvine discharges of the sick. It is, therefore, of the first importance that these should be disinfected. In cholera, diphtheria, yellow-fever, and scarlet-fever, all vomited material should also be looked upon as infectious. And in tuberculosis, diphtheria, scarlet-fever, and infectious pneumonia, the sputa of the sick should be disinfected or destroyed by fire. It seems advisable also to treat the urine of patients sick with an infectious disease with one of the disinfecting solutions below recommended.

* Read in the Section on State Medicine at the Forty-second Annual Meeting of the American Medical Association, held at Washington, D.C., May, 1891.

Chloride of lime, or bleaching powder, is perhaps entitled to the first place for disinfecting excreta, on account of the rapidity of its action.

The following standard solution is recommended:

"Dissolve chloride of lime of the best quality,* in pure water, in the proportion of six ounces to the gallon. Use one quart of this solution for the disinfection of each discharge in cholera, typhoid-fever, etc. Mix well and leave in the vessel for at least one hour before throwing into privy vault or watercloset.

"The same directions apply to the disinfection of vomited matters. Infected sputum should be discharged directly into a cup half full of the solution. A 5 per cent solution of carbolic acid may be used instead of the chloride of lime solution, the time of exposure to the action of the disinfectant being four hours." (Op. cit., pp. 237, 238).

The object of this paper is to inquire whether these recommendations, which were based upon the experimental data available at the time they were made, are sustained by subsequent investigations; and whether any other agents have been shown to possess superior advantages for the purpose in view.

But first we desire to call attention to another portion of the report of the Committee on Disinfectants. On page 236 the following definition of disinfection and disinfectants is given:

"The object of disinfection is to prevent the extension of infectious diseases by destroying the specific infectious material which gives rise to them. This is accomplished by the use of disinfectants. There can be no partial disinfection of such material; either its infecting power is destroyed or it is not. In the latter case there is a failure to disinfect. Nor can there be any disinfection in the absence of infectious material."

* Good chloride of lime should contain at least 25 per cent of available chlorine (page 92). It may be purchased by the quantity at 34 cents per pound. The cost of the standard solution recommended is therefore but little more than a cent a gallon. A clear solution may be obtained by filtration or by decantation, but the insoluble sediment does no harm and this is an unnecessary refine

ment.

For a very copious discharge use a larger quantity.