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PUBLIC RECORD OFFICE
Reference :-
C.O. 885
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PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
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Board of the India Office, as to my opinion of the Clayton Process for the destruction of rats in vessels coming from infected Ports. I was acquainted with the claims made on its behalf, and with the high opinion expressed by some who had used it especially the French Health Authorities at Dunkerque, but I thought it desir- able, under the circumstances, to test its capability and efficiency before hazarding a formal opinion, and for that purpose I communicated with the representatives of the Clayton Company, stating that I should like to see the method which they employed for the destruction of rats in operation on the first ship they might have occasion to fumigate in the Thames, and that I should like to be allowed to test for myself the effect of the fumigation. In a short time I was informed that the British India Steam Ship "Manora," recently arrived from Bombay, was placed at my disposal for experimental purposes.
3. Arrangements made with Professor Hewlett and Dr. Willson, of King's College, for a series of careful experiments to test the efficiency of the gas-Hav ing arranged with my colleague, Professor Hewlett, Professor of Bacteriology, King's College, and Dr. Willson, Demonstrator of Bacteriology, the tests which it was de- sirable to apply, the three of us visited the S. S. "Manora," on Wednesday, May 27th, with the object of seeing the process of fumigation, next of subjecting to the action of the gas bacterial cultures of plague, typhoid, cholera, and anthrax, thirdly, of noting the effect of the gas on vermin and insect life, and fourthly, observing its effects on food stuffs and fabrics likely to be carried by merchant ships.
4. The process originated at the Quarantine Station in New Orleans.-Ten years ago, when in India, I was much interested in the apparently excellent results as reported by the New Orleans Health Officer, which the Quarantine Authorities in New Orleans obtained by the pumping of the fumes of burning sulphur into cargo- laden ships arriving from yellow fever infected ports, combined with the washing of the decks with corrosive sublimate, and the steam disinfection of the personal effects of the passengers and crew. When plague broke out in 1894 I drew the attention of the Health Officer of the Port of Calcutta to the process as a possibly useful method of disinfecting ships arriving from China. It is accordingly with a particu- lar degree of interest that I find the Clayton Process for extinguishing fires, and the destruction of vermin to be a modified and improved method of the system used for so long a period at the quarantine station of the New Orleans Board of Health.
5. The mode of generation of the gas.-The gas, which analyses show to be a mixture of SO, and SO,, together with some unknown gaseous toxic combination of sulphur and oxygen is generated by burning rolls of sulphur at an intense heat in a very simply constructed apparatus, which is usually fixed on to a small launch, so that the machine may be brought to the side of any ship that requires fumigation. Air is supplied to the burning sulphur by an induced draught, which, at the same time, draws the heated gases so formed through a cooler attached to the apparatus. This cooler is kept at a low temperature by a continuous passage of water through From the cooler the gas, it. In this instance the water was taken from the dock. reduced in temperature and volume, passes to a blower, which propels it through a hose-pipe to the part of the ship that is to be fumigated. There is a return hose- pipe, which draws the air from the chamber that is being fumigated to the furnace. It is this air which first supplies the sulphur in the furnace with oxygen for combus- tion, but as the percentage of gas in the compartment that is being fumigated rises, the withdrawal of such air to feed the furnace cannot be continued as 5 per cent. of the gas in air possesses fire-extinguishing properties. Even a smaller percentage would cause the sulphur to burn badly, and tend to put out the fire. Accordingly, whenever the returning air from the apartment registers 3 per cent. the connection between the return pipe and the furnace is closed, and a valve is opened near to where the pipe enters, which permits an incurrent of fresh air to the furnace from the outside; when the percentage of gas in the furnace rises to 18, and there is a tendency to exceed this, in order to prevent any volatilization and deposit of sulphur along the pipes a second valve is opened, which keeps the percentage of gas formed in the furnace at a regular standard.
It will be understood, therefore, that the system is first one of propulsion and exhaustion, but that when the air exhausted contains 3 per cent. of gas, the exhaust pipe is shut off, and it is then a saturation of the air in the chamber up to the required percentage by propelling into it a high percentage of gas. A very simple
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contrivance indicates the percentage of gas that is being propelled or exhausted through the tubes, and by a similar test the percentage of gas in the compartment that is being fumigated can be ascertained.
6. Strength and properties of the gas, and comparison with carbonic acid gas.— Experience shows that a percentage of between 10 and 12 is sufficient for the pur- poses for which it is employed; a large machine is capable of generating 800 cubic feet per minute of 18 per cent. gas. The gas driven into the supply pipe emerges from it into the chamber to be fumigated in the form of a white fuming gas, which is exceedingly irritating to the mucous membrane of the respiratory passages when breathed in small quantities and in a confined space. The presence of the gas is thus readily detected and recognised by the irritating effect it produces on the respiratory passages and by the fact that it is visible. These two qualities are particularly advantageous for those employed in carrying out the fumigations. They are able to see the gas when it escapes from the pipes, and they are rendered so uncomfortable by the irritation of the eyes, nostrils, throat and chest as the per- centage of the gas increases in the room, that it necessitates a speedy retreat from the room to the fresh air outside, and thus there is no chance of the operators being injuriously affected by the gas. The gas itself has no effect on the clothes or person of those exposed to it provided fresh air is supplied for breathing purposes. In the experiments to be described later on the engineer who was conducting the operations put on a specially designed diving helmet and three times entered a passage and cabin containing air with a 10 to 12 per cent. of the gas, and removed articles which had been exposed for the time decided on.
The readiness with which the gas is detected compares it very favourably with carbonic acid gas, which is not only odourless but invisible and if breathed even in small quantities is liable to produce poisonous effects without any warning.
7. The nature of the experiments.-The experiments were made on two con- secutive days and consisted in observations on the effects produced by fumigation with the gas in the strength of 10 per cent. to 12 per cent. for two, four, or six hours on the following :-
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(1.) On rats and cockroaches in the ship.
(2.) On bugs, fleas, grubs, chrysales, mosquitoes, and mosquito larvæ and
pupæ.
(3.) On bacteria of plague, cholera, typhoid fever, and anthrax.
(4.) On meat and food-stuffs.
(5.) On fabrics of different kinds and colours, gloves, leather, gilt bound and
gilt edged books, furs, &c.
(6.) On the general condition of the engine-room, store-room, kitchen and
cabins and their contents after fumigation.
Rats and cockroaches. The first series of experiments were on the rats and cockroaches in the ship. The result of fumigation with the gas for six hours was 218 rats killed and large numbers of cockroaches. In connection with the destruc- tion of rats there was one particularly noticeable circumstance, viz., the great num- ber which were found dead a short distance from their holes, and which had evi- dently met with their death when rushing from their holes to escape the effect of the gas which had penetrated into their runs. As this appears to be the usual effect of the gas the nuisance which is feared to possibly arise from rats dying in their holes does not occur. I am informed that in ships fumigated with their cargo
in them the rats, intent in their rush for fresh air, usually manage to scramble to the upper parts of the cargo before they die. It does not require a six hours' exposure to this gas for the destruction of rats. Experiments showed that rats let down in cages to the hold containing 10 per cent. of the gas were killed in less than two
minutes.
9. Bugs, fleas, mosquitoes, grubs, and chrysales.The second series of experi- ments consisted in testing in a cabin with a cubic capacity of over 500 feet, the effect of the gas on bugs, fleas, mosquitoes, larvæ of mosquitoes, pups of larvæ, grubs and chrysales, which were placed inside bottles the mouths of which were covered with cloth or cotton.
1. (a) Bugs; (b) fleas.-One bottle containing bugs and another bottle con-
taining fleas were placed in a closed lantern.