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WASHINGTON BRANCH,
APRIL 13, 1880.

MEDICAL DIRECTOR T. J. TURNER, U. S. N., in the chair.

THE VENTILATION OF SHIPS.

BY PASSED ASSISTANT ENGINEER G. W. BAIRD, U. S. N.

MR. CHAIRMAN AND GENTLEMEN:—

I think that the carbonic acid exhaled from our lungs or produced by combustion on board ship is not nearly so injurious to health or comfort as the foul gases of the bilge or the organic matter from our exhalations. While serving on board the Pensacola—a vessel not overcrowded—we found the organic matter, deposited upon the knees, beams and ceiling of the vessel, on the berth deck, sufficiently thick to be wiped off by a pocket handkerchief, and clearly distinguished upon its surface.

In 1854 Dr. Thompson found that “the air of London when passed through oil of vitriol communicated a dark tinge to it, and if large quantities of air were passed through distilled water, the inevitable result was the formation of fungi.” And Dr. R. Angus Smith, (Op. Cit. p. 217,) tested the air for organic matter and found the proportion in the air. This table, published in the Chemical Gazette of 1859, is as follows:—

- - o Number of grains of LOCALITIES. Organic matter in 100 - Cubic inches Of air.

Manchester, England, . . . . . . . . . . . . . . . . . . . . . . . . . 52.9
In a pig-sty,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109.7
Thames, in warm weather, . . . . . . . . . . . . . . . . . . . . . . 58.4
Thames, Lambeth, . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43.2
Thames, Waterloo bridge, . . . . . . . . . . . . . . . . . . . . . . 43.2
London, in Warm weather, . . . . . . . . . . . . . . . . . . . . . . 29.2
London, after a thunder storm, . . . . . . . . . . . . . . . . . . 12.3
Northern Italy, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6
German Ocean, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3
Lake Lucerne, . . . . . . . . . . e e o e e o e s to e o e a e o e o e o e e 1.4

It will be seen that the amount of organic matter varies considerably in different localities and under different circumstances, and I regret that I am unable to give the proportion of this poison found on board our ships. It is a subject now under investigation by the surgeons of the Navy, and, though the tests for it are complicated, I hope at no distant day to see a full analysis, as found on board all classes of our vessels, published by the Medical Bureau. Pasteur supposed “that germs of infusoria were present in all air, and the cause of fermentation and putrefaction,” and Van der Broeck, Shroeder and Deuch have confirmed his views. They found that almost all organic substances, even those of ready putrefaction, such as blood, fibrine, albumen, sugar, etc., were preserved unaltered when heated to the boiling point in a bottle, stopped by a loose plug of raw cotton, so that in cooling the entering air would be filtered and deprived of floating solid substances. The amount of carbonic acid in the air seems to be as inconstant as that of organic matter. In the densely populated parts of Europe we find a much greater quantity than in any parts of America, excepting in the volcanic regions of South America. Dr. Wetherell estimates the mean amount of carbonic acid in the air, for all parts of the world, to be four parts in ten thousand, so that in estimating the amount of air necessary for the dilution of this gas to its normal, we will base our calculations on this fraction. The quality of this gas appears to be more deadly than its quantity, for I have read that La Blanc found that “a bird died in a room containing less carbonic acid than existed in the air of many apartments he had examined; and a dog survived longer in air containing the enormous amount of nineteen hundred and ninety-one volumes per ten thousand of carbonic acid than in an atmosphere from burning charcoal in which three hundred and one volumes of this gas were present.” The cause of the latter superior deadly effect was attributed, by competent authority, to the presence of the poisonous carbonic oxide, emitted by imperfect combustion. The presence of carbonic acid on board ship, when produced by exhalation, is an indication of the presence of organic matter, and they bear, in that case, nearly a constant relative proportion to each other, so that the tests now being made on board our ships for carbonic acid may be relied upon as an index for organic matter as well. What this ratio is I am unable at present to say, but I hope soon to see published

the work our surgeons are now doing on this subject.

Pettenkoffer, La Blanc, Roscoe and others have made some very interesting experiments on the escape of carbonic acid through the crewices of rooms, condensation upon the surfaces of, and diffusion through the walls of apartments, but I have not been able to find any similar tests for organic matter. Dr. Wetherell, in his celebrated experiments found the carbonic acid in the public schools of Washington ranged from 9.342 parts in ten thousand, to 17.184 in ten thousand, and during the same month he found only from 4.275 to 7.355 parts in the United States Senate Chamber, and while there were no complaints from the schools of ill ventilation, we have heard many from the Capitol extension. There must have been some other offensive matter than the carbonic acid in the Senate and House of Representatives, and it may have been organic matter, for we are informed that Professor Leeds found decaying animal and vegetable matter in the very conduits which bring the air from the fans to the Senate Chamber and the House of Representatives. On board ship we have more than this to contend with. On board all new ships, and also those which have been lately repaired, we find the bilge pumps frequently choked up by chips and shavings. As the bilges are cleaned and inspected before a vessel leaves the navy yard to commence a cruise, we naturally ask where these shavings come from? We observe they appear most abundant when the ship has considerable motion, and infer that they must have worked or fallen down from between the timbers where the ship is ceiled in. As this stuff decays it evolves gas abundantly. Letting water into the bilge and pumping it out daily will remove the bad odors, but if the watering be neglected for a single day the stench is worse than usual. In order to prevent the evolution of gases by the bilge we must keep it dry. The large amount of air received into a ship through the wind sails alone is more than enough to purify the air so that no trace of odor could be detected, were the air properly distributed; but this blast takes the most direct course to the nearest outlet and escapes, causing, in its passage, but feeble eddies in the other parts of the vessel. It is evident that we must remove these foul and poisonous gases first, and afterwards direct our attention to the supply of fresh air. DIRECTION OF THE PRODUCTS OF RESPIRATION.—The question which now presents itself is whether it is better to remove foul gases through openings near the floor or near the ceiling. Mr. Goldsworthy Gurney, who ventilated the House of Commons, informs us that the breath is forced downwards to the ground from the

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