heading of Plumbing. The safe-trays under baths, sinks, and closed-in closets (which latter, by the way, are not to be advised, and are rapidly getting out of date) must be carefully made, and the overflow drain requires very careful fixing. It must be made of 1-in. to 2-in. pipe, be fixed as shown in fig. 737, and deliver by an open end. No trap is required, but a light copper or aluminium flap is an advantage on the outer end. House sinks should be made preferably of glazed earthenware; those made with wood lined with lead or copper will not give good results. The lead used for lining The waste pipe should should be 8 lbs. in weight to the superficial yard. be placed in a corner of the sink. On ground-floors the waste and trap should be of 11-in. drawn lead or cast iron, delivering into the back inlet of the grease trap, but on upper floors, to prevent syphonage, the trap shown in fig. 738, known as Helleyer's trap, may be provided. It is a very simple. and excellent form of trap for the purpose, owing to the bell-mouth inlets and square outlets. The erection of small flushing-tanks is usually left to the discretion of the plumber. We are referring to those tanks for such a purpose as flushing a series of closets in schools, asylums, and other large buildings. It is essential that the pipe be set truly vertical, and the top rim curved inwards. This is so that the first flow of water will fall down the centre of the pipe and cause a good vacuum. If a trap happens to be interposed between the flushing tank and its place of action an air-break must be introduced somewhere between it and the tank. We before denounced the hopper closet, but we confined our remarks to the long hopper closet, because although we do not advise the general use of such appliances, the short hopper closet may be used in yard w.c.'s, where it would be connected with the drain direct, and so avoid any risk of faulty plumbing. The erection of house cisterns demands the attention of the engineer. They are preferably made of galvanised iron, but where the water has no tendency to eat away the lead, wooden lead-lined cisterns, provided the plumbing is properly done, may be found very satisfactory.* All cisterns without exception must have tight covers. They must be large enough to provide sufficient storage, but not so large as to cause contamination of the water supply. The supply pipes from the main must be carried up internal walls so as to prevent damage by frost, but where they are carried on the inside of main walls (they must never be outside) they must be nailed to 1-in. boards and boxed in, the boxes being filled with sawdust, felt, or cocoa matting. Pipes on roofs should be boxed in likewise, and every precaution taken against frost. Perhaps the most important point of any is the cistern overflow, which must, without exception, be provided. They must under no circumstances whatsoever be connected to soil-pipes, rain-pipes, bath wastes or vent pipes, but must simply deliver by a short length of pipe into the open air, so as to prevent any contamination of the cistern water, and to give warning when they are in use. They must be of larger bore than the supply pipe, and all w.c. cisterns should be similarly fitted. No water for drinking purposes in town houses should be taken from cisterns; a special tap off the main should be provided. The writer has inspected some cisterns in Ireland which would make any ordinary person ill for a week to look at, let alone drink the water therefrom. Dead mice and rats, to say nothing of cats and other putrid refuse, are frequently found in the cisterns of old houses, which have no proper covers. Infection and Disinfection.-Before concluding our chapter on sanitation, it may be well to say a few words on infection and disinfection, because, although the work is primarily entrusted to the sanitary sub-officers of a town, these gentlemen are usually under the jurisdiction of the borough surveyor, and a few words on their work will, I hope, not been deemed out of place. Regarding diseases, the first stage is termed Incubation, being the period before the disease manifests itself, then comes Invasion, and finally convalescence. Patients with infectious diseases must always be isolated completely. The practice of hanging sheets outside the room door, even if soaked in disinfectant, is absolutely useless. The terms "disinfection" and "disinfectant" can only be applied to the absolute destruction of disease virus, the various processes being known to the public under these terms being only merely antiseptic or deodorant. A disinfectant must, to be of any practical value, arrest the growth of, and absolutely destroy, the morbific agent; it must be applied to every part of the affected substance in sufficient strength, and for an adequate period. There are three main methods of disinfection, viz.— 1. Heat (which may be dry or moist). 2. Chemical substances (liquid or powder). It need not be greater than 212° Fahr., and moist heat is preferable to dry, because it has both a greater and * Slate has also been satisfactorily used. a more rapid penetrating power, in the proportion of 18 minutes to 8 hours. The machine which seems to give the most satisfactory results is Ransome's hot-air regulator (dry heat). The advantages of steam disinfection above hot air are 1. Every engineer knows that steam will liberate latent heat. This is, of course, liberated into the articles. 2. In dry heat there will always be a natural loss in evaporating any moisture present in the articles. 3. The condensation of the steam in the articles causes a loss of pressure, and continual admission of fresh steam is essential. 4. Again, saturated steam is in all cases preferable to super-heated. The most efficient steam disinfector seems to be Recker's, in which the pressure may vary between 1 lbs. per sq. in. (216° Fahr.) and 7 lbs. (230° Fahr.), but the cost of the apparatus is high (about £80); and for places where the amount of disinfection would only be small, and not enough to warrant the expense of an elaborate apparatus, Threshe's disinfector, on the same principle (steam), has given good results; but to obtain a higher temperature than 212° a solution of chloride of calcium is used, because it has the property of having a higher boiling-point than water. Then there is chemical disinfection, the most generally used chemicals being corrosive sublimate (bichloride of mercury), 1-1000 part solution, formalin, cyllin, and chinosol (1-1000 part solutions), and carbolic acid (phenol), 1-20 part solution. Regarding the use of all these, they must be of such strength to come in contact with the germs without undergoing further dilution. Corrosive sublimate is the most powerful of them all. It is very poisonous and must be very carefully handled, which precaution is particularly desirable on account of its natural colourless form. Formalin is the name which is given to a 40% solution of formic aldehyde, which is a gaseous alcoholic compound. In use a 2% solution is sufficient (2 of formalin to 98 of water). It has the paramount advantage of being non-poisonous. It is also cheap, costing less than carbolic acid. Cyllin and chinosol are patent disinfectants. Chlorine is rather useful, especially for washing walls, for which a 1% solution is sufficient. "Chloros" is a solution of sodium hypochlorite, containing 10% of available chlorine. Condy's fluid, though useful for keeping things sweet and clean, is almost too expensive for disinfecting work, because such large quantities would be required. The reason is that the permanganate is used up in oxidising the organic matter in the infected substance. Fumigation by sulphur is a very satisfactory way of disinfecting buildings. The amount required is about 14 lbs. per 1000 cub. ft. of space. In use it is placed on a tray in the centre of the room, and a little alcohol poured on to it to give it a start, when it will burn continually till all gone. All windows and doors, etc., must be closed, and preferably sealed with brown paper. Chlorine gas is also used. It may be generated by pouring strong HCI on to chloride of lime in the quantities of 2 pints of HCl to 1 lb. of chloride of lime per 1000 cub. ft. of space. Or it may be produced by mixing one ounce of common salt with oz. of oxide of manganese, plus oz. of H2SO and oz. of water. Apply the solution to the powder, preferably in a hot basin. But formic aldehyde vapour is superior to both the above processes (sulphur and chlorine). To produce it, paraform tablets are used in an Alformant lamp, or better still, a "Linguer" machine used. To produce "glyco-formal," used for disinfecting purposes in the same way as formalin, a solution of formic aldehyde, glycerine, and water is used. In all cases of fumigation the rooms must be sealed for at least six hours. When paraform tablets are used, it will be necessary to burn 10 for each 1000 cub. ft. of space, the walls being afterwards painted with a 5% solution of formalin. It may here be mentioned, the formalin has hardly any penetrating power, being merely a superficial disinfectant. But it will not damage metals or colours (except aniline blue). The various actions of disinfectants are as follows: 1. Metallic salts and mineral acids combine with organic matter, and thus forming a permanent compound, prevent the action of bacteria. 2. Substances such as charcoal condense the oxygen within their pores and help to destroy animal matter. Condy's fluid will give out oxygen and so form CO2, while sulphurous acid deprives substances of their oxygen. Corrosive sublimate will be neutralised by proteid nitrogenous matters and albuminoid matter; in such cases an excess over the ordinary quantities has to be used. For disinfecting typhoid excreta (a very necessary precaution in the case of outbreak) use the following:— Corrosive sublimate Sulphate of iron oz. to one gallon of water. Chloride of zinc 1 quart to 3 quarts of water. Carbolic acid (Calvert's No. 5) a 5% solution. To produce nitrous acid gas for disinfecting purposes use oz. copper filings, oz. nitrous acid, and oz. of water. It may here be stated that those compounds termed nitrous contain less oxygen than those termed nitric. Nitre is nitrate of potassium. For disinfecting stone and tile floors, use sawdust which has been saturated with H2SO4; and for disinfecting sewage, sulphate of iron only is of any practical value. Very often old offensive burial-grounds have given rise to nuisance. They must be raked over, fresh earth put on, trees planted, and good stiff grass sown. A spreading of unslaked lime is an advantage. The subject of disconnecting traps is at present a very vexed question, therefore no doubt the views of a very eminent member of the sanitary engineering profession may prove of value and interest to the reader. At a meeting of the Sanitary Inspectors' Association held recently at Bath, Mr T. J. Moss-Flower, C.E., F.R.Sau.I., opened a discussion on the disconnecting trap in drains. Mr Moss-Flower stated that he considered it most desirable that there should be fixed on the line of drain between the house and the sewer an intercepting trap, so as to keep the sewer air as far from the house as possible. In his opinion, the fixing in a proper manner of an intercepting trap of suitable size, shape, and form affords an effectual barrier to the passage of any germ of disease or sewer air from the sewer to the house. He had examined the drainage of houses where there was no intercepting trap between the house and the sewer, and the sewer air was enabled to pass freely to the inside of the house, through defective drains and sanitary fittings, and this state of affairs was alleged by medical attendants to have been partly contributory, if not the direct cause, of the specific form of disease from which the inmates were suffering. He had also examined the drainage and sanitary arrangements of a large number of houses where in each case there was an intercepting trap on the line of drain, and gave particulars of the defects discovered, such as periodical syphoning of traps of w.c.'s, which allowed drain air to enter the house, and which, but for the intercepting trap, would have given a free and uninterrupted passage to the house for the sewer air. In the absence of a trap on the line of drain, any germs of disease which may find their way into the sewer, from an infected stool or otherwise, may pass up the house drain of a neighbouring house and into the house through one of the numerous defects that may exist in the drains and general sanitary arrangements, and be imbibed by the inmates. He had never known any evils to arise in connection with the numerous systems of drainage constructed by him during the last twenty years in connection with which intercepting traps were fixed, and of the large number of intercepting traps fixed by him he has only known of one becoming choked, and that was due to the carelessness of workmen in allowing some cement to fall into the well of the trap. In Mr Moss-Flower's opinion, the abolition of the intercepting trap would prove very disastrous, and it would not be thought of in any case unless the public sewers were constructed, covered, cleansed, ventilated, and kept at all times so as not to be a nuisance or injurious to health, and the house drainage and general sanitary arrangements of all houses draining into the public. sewer were also constructed and maintained constantly in a perfectly sound state; and since it is not possible to ensure this, the intercepting trap is the best safeguard to the health of the inmates of houses. Where complaints have been made against the use of the intercepting trap, they arise from one or more of the following defects : (a) The trap is too large or too small; in the former case difficult to flush, and in the latter liable to choke. (b) The trap is of improper shape and form, offering obstacles to the flushing out of its contents. (c) The invert of the outlet of the trap being on a level with, or above the level of, the inlet, in the latter case causing the sewage to pond back in the drain. (d) Carelessness of workmen in fixing the trap out of level, either tipping it towards the outlet, thereby breaking or reducing the water seal, or tipping it towards the house, and making the outlet higher than the inlet, and causing the sewage to pond back in the drain, as in (c); also in not clearing the cement from the inside of the pipes at the joints, etc. (e) By fixing the traps, in cases where there are no special automatic flushing tanks, so far from the house that all ordinary flushes of water have so spread out along the invert of the drain as to have no flushing power by the time it reaches the trap. (f) By giving too little fall to the house drains to which the traps are connected, causing the traps to choke. (g) In the case of disconnecting chambers, by fixing intercepting traps with inspection eyes, leading to sewer, these inspection eyes being capped by a plain stoneware disc which can be easily blown out by pressure of air or otherwise, and the stoppers under normal conditions being seldom tight, and allowing sewer air to enter the drain. (h) By a variety of other avoidable defects. The foregoing defects, the speaker maintained, can be avoided if proper care be observed. By carefully selecting the trap, and taking due care in fixing and in selecting the position for it, no evils need arise; and as regards the inspection eye on the outlet end of manholes, the disc closing the opening should be so arranged that it cannot be removed by sewer men thrusting the rods up the house drains from the sewer, or by pressure caused by sewage or air, and yet so as it could, if necessary, be quickly opened from the groundlevel without entering the manhole. Mr Moss-Flower has made detailed examinations of a large number of premises where one or another of such diseases as typhoid fever, diphtheria, blood-poisoning, etc., has broken out, and in every case he has found serious |