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in a dungeon only eighteen feet square, of less than 5.900 cubic feet, with two small windows on one side, of whom 123 died in a single night; the master of the emigrant steampship Londonderry, on her passage from Liverpool to New York, in 1848, on account of stormy weather, forced 200 steerage passengers into a steerage eighteen feet by eleven and seven feet high (thus allowing but seven feet of cubic space to each person), and closed the hatches upon them; on the removal of which, in the morning, there were seventy-two dead and several others expiring in convulsions, and with blood starting from their nostrils, ears and eyes; and by the act of a “distressed American seaman," the chief mate of the ship Waverly, of Boston, in 1858, who complained of "hard treatment” because he had been sentenced to jail four years for having confined 400 coolies below decks for twelve hours, during which time 270 were suffocated: these examples, to which others might be added, are cited as object-lessons worthy of continual repetition in school books.

Carbon dioxide is commonly considered non-poisonous, but only, as above described, irrespirable. But this is an error. Numerous experiments on animals have demonstrated to the contrary. R. Angus Smith found that thirty volumes per 1,000 atmospheric air caused great feebleness of the circulation with usually slowness of the heart's action and quickened respiration. These effects lessened when the amount was smaller, but they were evident when the amount of carbon dioxide was only one volume per 1,000—an amount often excelled in dwellings, particularly in bedrooms.

Symptoms of carbon dioxide poisoning are irritation of the throat, headache, giddiness, singing in the ears, drowsiness, gradual loss of muscular action of the heart, hurried respiration, syncope, nausea, and sometimes vomiting and convulsions; and, finally, as these symptoms disappear under continued exposure, coma and death. Few are the teachers in our public schools who have not observed some of these symptoms.

The Air of Subways.—While writing this article, the report comes to us that Prof. D. A. SUTHERLAND has lately made a series of analyses of the air of the London “tubes" with results that should not fail to attract the attention of the engineers of the New York Rapid Transit Commission. If they are relying in any sense upon London experience, it is evident that the results in that city should not be accepted as satisfactory for New York. The fact was established by test that the air of the street outside the tube stations of the Central London Railway contains normally an average of 2.83 parts of carbon dioxide in 10,000. Tests made inside the stations and in cars under various conditions gave the following mean average results:

7.36

During hours of limited traffic

Carbonic acid in 10,000 vol

umes of air. On platforms at 8.15 A. M........

.............. 4.23
On platforms (Saturday), 7 P. M..

3.74
In elevator, 10.10 A. M..........
In cars, 9.30 A. M., from city......

4.33
In cars, 1.30 P. M., from city.......

5.33
During hours of heavy traffic-
On platforms, 4 to 7 P. M........

11.04
In cars, 9.30 A. M., to city........

16.65 In cars, 4 to 5 P. M., from city....

13.74 In cars, 6 to 6.45 P. M., from city..... ....... 15.54 In cars, 6.10 P. M., from city.................. 20.46

The carbonic acid tests were made between the 11th and the 15th of December. The range of outside temperature was between 37 and 56 F. The range of temperatures on the platforms was between 56 and 76 F., and in the cars between 66 and 76 F. The barometric pressure throughout the period of the experiment was very constant, ranging between 30.1 inches and 30.2 inches. Readings with the anemometer showed an air movement due to forced draught and train movement of from one mile to five miles per hour. Some of the tests were made with the Chattaway and Wharton apparatus, and some by the Pettenkofer method. One method was employed to check the other, and the mean average result was 16.62 volumes of carbon dioxide in 10,000 volumes of air.

The ventilation of a crowded car is difficult even under the · most favorable circumstances. But the figures above cited have

especial significance with reference to the Pennsylvania terminal and for those who will have professional responsibility for the Hudson River trolley tunnel now building.

As the result of careful observation and repeated experiments on a practical scale it has been ascertained that the air of occupied rooms vitiated by the presence of more than 0.8 per volume of carbon dioxide (twice the average amount in the atmosphere), is dangerous to health. The danger, however, is not wholly attributable to the excess of carbon dioxide, but as much to the diminution of oxygen.

While it is impracticable to maintain the same degree of purity of the air of any occupied enclosure as that of the atmosphere, the object of all methods of ventilation is to approximate that condition as nearly as practicable.

Ammonia is a light, colorless, gaseous chemical compound, one of the products of the decomposition of nitrogenous organic matter. It consists of one equivalent of nitrogen and three equivalents of hydrogen. It exists normally in the proportions of about three and a half volumes in every 10,000,000 of atmosphere. In other words, in ten millions gallons of atmospheric air the amount of ammonia gas present is, on an average, about three and a half gallons; it frequently exceeds this, however, and wherever it does it is always suggestive of impure local conditions.

It possesses a strong pungent, familiar and offensive odor, common in the vicinity of horse stables, from the manure of which it is often evolved with dangerous significance. For all accumulations of organic matter in process of putrefaction are more or less dangerous to the neighborhood as localizing conditions of infectious diseases. The disagreeable odors emitted by organic matter in process of decomposition, ammonia gas, or other, though useful as a warning of its proximity, adds to the danger by stimulating the sensitiveness of persons exposed to it and thereby lessens the power of resistance to disease.

Ammonia is exceedingly soluble in water and hence it cannot long remain in excess in the atmosphere in regions subject to nature's great air cleansers, rain and snow, by which it is deposited on the surface of the earth. Rain water always contains ammonia in solution, and it is this which gives the apparent sensation of softness to rain water experienced in its use. Nevertheless there is always some ammonia present in the air roundabout, doubtless because organic matter of one kind or another, in process of decomposition, is also always roundabout, and of this the presence of ammonia is evidence. In an address on “Air as a Sanitary Agent,” delivered at the Sanitary Institute of Great Britain by Dr. Angus Smith, the distinguished author of the celebrated work in “Air and Rain," a few years ago, occurs the following practical remarks with regard to the significance of ammonia:

“When a room is shut up even for a day, unless the room be very large indeed, there is always that peculiarity observed by sensitive persons to which would be given the name of closeness. Yet there are people who do not seem to observe this and who spend their lives in rooms in which this closeness may be constantly observed. I have often reflected on this peculiar condition. Surely if oxygen removed all impurities these impurities ought to have been removed, since the oxygen of the air is never absent from the rooms except to such a small extent that the estimation of the change is extremely difficult. If we lift up a window and allow the air to blow into the room so as to replace the original air we do not at all times attain efficient aeration. It takes but a few minutes, in a climate where there is considerable motion in the air, to renew the atmosphere of a room entirely. We may judge of this by making a trial upon a visible atmosphere, viz.: one pretty well filled with smoke. We see how rapidly, with an open window, every trace may be removed from the farthest corner, and yet this new air is not sufficient to refresh the room, and closeness is the characteristic still complained of. It is the custom in well-regulated houses not to renew merely the air, but to cause the air to blow through the house for a considerable time every day when the weather permits it. Knowing this for a long time I wondered much what was the reason. Surely, I said, there was vital air enough without the long-continued current. Looking further at this subject it occurred to me that really clean houses were preserved in this condition by something more than currents of air, generally, and that good housewives resorted to the practical methods of rubbing by hand, and it seemed clear that no furniture could be preserved from the peculiar condition of mustiness in any house where the doors and windows must be frequently closed unless the absolute removal of certain substances from the surface was resorted to. And what was this substance that required to be removed ? I supposed it to be one of organic origin. If organic matter is everywhere, the presence of ammonia is everywhere possible; and if that matter is decomposing, ammonia is everywhere present; that is the general statement which this paper illustrates. It is now many years since it was observed by me that ammonia could be found on surfaces exposed to exhalations from human beings, but it is not until now that the full significance of the fact has dawned on me and the practical results that may be drawn from it in hygiene and meteorology. These results are that ammonia may be an index of decayed matter. This does not apply to the substances which may be called germs, whether it be possible to see them or not, because they are not bodies which have passed into the ammonical stage, although some of them may be passing—those, for example, which are purely chemical and exert what we may call idiolytic action.

“As a part of the atmosphere ammonia touches all substances, and can be found on many; it is in reality universally on the surface of the earth in the presence of men and animals, perhaps attached more or less to all objects, but especially to all found within human habitations, and we might also add, with equal certainty, the habitations of all animals.

“This ammonia on the surface is partly the result of decomposition continually taking place, of organic matter adhering to everything in dwellings. The presence of organic matter is easily accounted for, but it is less easy to detect than ammonia. It is probable that the chief cause of the presence of ammonia on surfaces in houses and near habitations is the direct decomposition of organic matter on the spot. If so, being more readily observed than organic matter itself, it may be taken as a test, and the amount will be a measure of the impurity.”

CONSUMPTION IN THE BRITISH NAVY.–Gerald Sichel says (“British Medical Journal," Oct. 4, 1902) it may be confidently assumed that in the navy, as elsewhere, the lungs are par excellence the favorite sites both for infection of the individual patient and for the propagation of the disease to others. Tuberculosis costs the English navy £20,000 per annum. The question of ventilation is of the first importance so far as the cure of consumption is concerned. The remedy for this disease is in prevention rather than in cure; that is, in prompt diagnosis. Careful microscopical examination probably affords the surest and earliest method of making a reliable diagnosis. On the other hand, exceptionally, the bacillus can only be demonstrated after prolonged and frequent search in cases in which physical signs point to advanced disease. Once tubercle bacilli have been demonstrated, the only proper course is to at once invalid the man out of the service. The writer concludes by emphasizing two important practical points: (1) We should consider it our earnest duty, more particularly on board ship, to carry out the needful simple examination of sputum systematically. (2) Every medical man, whenever he gets the opportunity, should urge the necessity for compulsory notification of tuberculosis throughout the country.

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