CO885-(7-8) — Page 136

PUBLIC RECORD OFFICE

Reference :-

FITUC.O.885

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PUBLIC RECORD OFFICE, LONDON

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which should be diluted with about eight times its volume of water before adding it to the chalk. Proportionate quantities of chalk and vitriol and water are required according to the cubie capacity of the hold and the thickness or depth of the layer of carbonic acid required. The vessel, so shaped and fixed as to prevent the contents being spilled over, should be placed in the lower part of the hold with the necessary quantity of chalk, and then the diluted oil of vitriol should be added either directly or from a pipe which has been led down from the upper part of the hold to the vessel. Before adding the vitriol some pieces of cheese or other article of food might with advantage be placed near the vessel or the centre of the hold. As the gas will only rise very slowly the depth of the layer of gas can be easily tested by letting down a lighted candle; immediately the carbonic acid gas is reached the flame is extinguished. Three or four hours after the generation of the gas has been completed, the hold, which during this time has been shut down, should be opened up and thoroughly ventilated so as to get rid of the carbimie acid gas. The state of the hold as to the safety or otherwise of any- one descending into it can easily he determined by letting down a lighted taper. So long as the flame is extinguished or burns feebly it is unsafe and the ventilation is not complete. This method can also be applied when the vessel arrives in port, though the most usual method, and one which has proved effective, is the pumping into the hold of the ship sulphurous fumes obtained from the sulphur furnace provided by the Port Health Authorities. If there are no special shafts down which the pipe conveying the sulphur dioxide gas can be passed, a sort of temporary shaft down to the lowest part of the hold is to be nude by removal of some of the cargo. Whichever method is adopted, special care should be given to cargo vessels, which are often infested with a great number of rats, There is on record an instance in which, after sulphur fumigation of a cargo steamer of about 3,500 tons, no fewer than 16 deck buckets of rats were taken from the holls, Both methods can be applied when the cargo is still in the ship, and there should be in every port the necessary appliances, A third method of destroying rats, but one which can only be applied to the hold when empty, has been tried at Hamburg, and is reported as having given good results, It consists in spraying into the hold a quantity of Pietoline." ~ which appears to be a chemical preparation containing certain diffusible gases mixed with sulphuric acid. Its use is injurious to merchandise owing to the sulphuric acid which it contains, and its application is, therefore restricted to the destruction of rats in empty holds. Until the rats are destroyed the cables which moor the ship to the shore should have con- trivances fastened on them to prevent rats getting from the ship on to the shore. There is in use in many places a sort of funnel-shaped apparatus, consisting of a tube of tin or iron, having on it a trumpet-like flange. The cable is put through the tube and any intervenung space is stopped up.' The apparatus

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is placed close to the ship. This arrangement prevents; rats from creeping along the cables from the shore on to the ship, or from the ship on to the shore. Trains bringing merchandise from infected localities should also be inspected, in order that all rats may be killed and destroyed.

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14. For the early stamping out of the plague epizootie among Measures rats on shore, by the destruction and extermination of the rats, necessary for it is necessary that the information as regards mortality should the stamping not be left to chance observation. It is essential that in the out of rut event of a locality being threatened with plague on account of a focility. neighbouring district being infected, or on account of any com

plague in a munication direct or indirect with a plague-infected port, that a systematic and regular inspection of houses in the poorer quarters, and in the neighbourhood of the docks, warehouses, grain depôts, and other buildings which are likely to contain rats should be made, in order to ascertain if there are any sick or dead rats, The inhabitants should also be warned to report the occurrence of any mortality among rats. If the authorities are thus on the alert, there is no difficulty in recognising rat plague. As has already been stated, the rat leaves its hole, is dazed, bleary-eyed, hobbles about, staggers, falls and soon dies. Examination after death shows its glands to be enlarged, congested and agglutinated, its internal organs to be congested, and its blood, spleen, liver and glands to be full of plague bacilli. These plague bacilli when stained look like diplo-bacteria, single or in pairs. They grow ou nutrient agar, and if cultivated in a flask of bouillon to which has been added some oil, they grow down into the depths of the liquid and form beautiful stalactites. Cultures on agar or in bouillon inoculated into mice or rats reproduce the characteristic disease. On account of the disposition of the rats to leave their runs, when ill, the epizootic among them whether in a house, warehouse or street, soon attracts attention. In an infected locality, the mumber of rats to be seen, their peculiar behaviour and their obvious illness combined with an unusual mortality among them are phenomena which are not easily overlooked. If these occur- rences are not noticed at the commencement and prompt measures are not undertaken the mortality among the rats becomes so widespread in a locality in which an epidemic is impending that it is impossible to escape attention, for dead rats are then to be found in the houses, depôts and streets, and create a most objectionable muisance. It is then rather late in, the day to begin the campaign against the rats. borne in mind during the height of the epizootic in the infected Another fact to be locality is the likelihood of the sudden appearance of an unusual number of rats in one or more of the adjacent localities, and that this has an important bearing on the dissemination of the disense. Areas which were formerly free, or comparatively free, of rats become infested with them. This is due to the emigration of healthy rats from the infected locality. Apparently urged by the instinct of safety the rats leave the locality which is bringing