These lectures were presented bj^ Dr.J. B. Cohen^ of Yorkshire College, Leeds, England, in Hodgkins Fund, Smithsonian Institution Prize Competition.]. Since we cannot bring clean air to the city, let's go looking for it in the countryside or by the sea: that is, those of us who can afford it. The health of a city can be compared with the health of a country by means of statistics from the health reports of health officials.
My friend and colleague, Mr. Wager, of Yorkshire College, took some trouble to obtain statistics on these points with regard to Leeds, and found that the percentage of deaths from diseases of these organs was considerably greater in the city than in the surrounding area . Before I pass to the subject of "Urban Air," I would like you to understand and keep well before you the idea that we live at the bottom of a great ocean of air, that we are surrounded on all sides. It constitutes about four-fifths of the total bulk of the air, and serves to dilute the other constituent, oxygen, which is the active part.
Its presence may best be shown by exposing to the air some pure lime in a glass basin, when the surface is quickly coated with a white film of carbonate of lime. By slowly inverting another beaker containing carbonic acid over the open mouth of the suspended one, the latter is filled with heavy gas and descends.
THE AIR OF TOWNS. 7 turbid indicated the presence of carbonic acid.) It is given off from the
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OXYGEN
NITROGEN
Based on Professor Koberts-Austen, we argue that a difference of one tenth of a percent of carbon in steel rails may be a very serious matter. The steel cylinder of compressed oxygen which recently burst at Bradford station with such fatal effect contained only three-tenths of a per cent, too much carbon—an amount, however, quite sufficient to account for the accident. The steel dies used in the mint should hold an average of 40,000 coins, but if the die contained one-tenth too much carbon, it would not strike 100 pieces without cracking.
Iscarbonic acid is really so poisonous that a quart or gallon more of carbonic acid and a corresponding quantity of less oxygen would be injurious to that extent." It is sulfuric acid, which accompanies the burning of coal and gas; it is the organic poison which accompanies its emission It is evidently very important to determine the small differences of carbonic acid in the air, so that we may guard against the smallest increase of carbonic acid in the atmosphere.
34;Weallavoidan atmosphere of 0.1 percent of crowded rooms, and the experience of civilized think that it is not only disgusting, but unhealthy.
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112,600 gallons of air in twenty-four hours, or the exhalation of 16 cubic feet 2,600 gallons of air in twenty-four hours, or the exhalation of 16 cubic feet per hour of air containing 5 per cent, of carbonic acid. In order to keep the air relatively fresh, the amount of carbonic acid should not rise above 0.06 percent; that is, the amount of carbonic acid should not increase by more than 0.02 per cent, supposing the air to have originally contained 0.04 per cent. On introduction of the Bunsenburner at the bottom opening a strong upward current of air. is produced, causing the spiral j), twisted on a horizontal bar, to revolve rapidly.
Strips of tissue paper rubberized around the edge of the top opening form vertical bands, also indicating the presence of air flow.
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17green color then pale, without disturbing the sooty dej^osit on the green color then bleaclied, without disturbing the sooty dej^osit on the other half. This acid, like soot, is derived from . coal, because it is never found in the country. The sulfur in the coal, .. which is present to the extent of 1 to 3 percent, burns, and part passes through the chimney as sulfuric acid, and then into the open.
In the open, it is quickly converted into the .. much more corrosive substance - sulfuric acid, which almost always . accompanies soot and it is found with soot on leaves and probably promotes their early wilting near cities. It has been said that no matter how much you can remove the smoke, you will never remove this acid; it will still i)assine in the air.
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THE AIR OF TOWNS. 19 which might by other find better means be prevented, he violates the
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THE AIR OF TOWNS. 21 INSTANCES OF FIRMS USING SMOKELESS FURNACES
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Before going to the subject of the city fog, I would like to say a word or two about the weight and number of those dust mites that we. By making use of a small vessel and dusty air greatly diluted with air free from dust, he succeeded in producing an apparatus, in which the dew-drops or fog-drops are sufficiently small in number to be counted. It consists of a shallow circular metal box of known capacity, fitted with glass plates at the top and bottom.
Under them is a plug of cotton wool, and at the bottom of the cylinder, which is closed at the end, there is a small hole through which air can enter. By pulling the iDiston down with the tap in the position shown in the diagram, air enters the metal box through a cotton plug, freeing it of dust. The piston which is at the top is now^ pulled down and a sample of dusty air is drawn up with the filtered air into the metal box.
The following is the average number of dust particles in town and country, taken from Aitken's observations: Country, 8,000 to 100,000 per cubic inch; city, 1,000,000 to 50,000,000 percubicinch.
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THE AIR OF TOWNS. 31 of beautifying our buildings and streets and squares, and of realizing
The Germs of the Air
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THE AIR OF TOWNS. 33 Yeast would also find its way into tlie brewer's wort; but this liquid is
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this. moreover, it manifested itself in the stunted and uneven growth of the caterpillars, in their eagerness of movement, fastidiousness in regard to food, and premature death. The black spots that appeared through the silkworm's transparent skin were examined and proved to be living brains. These gradually occupied the intestinal canal and expanded, finally filling the silk cavities, so that the worm, when its time came, automatically went through the process of spinning, but without j)roducing any silk.
By careful and constant use of the microscope he followed the life of these fatal bodies. When it emerges from the egg the worm, which is not much larger than the head of a needle, begins to feed and grow, shedding its skin from time to time when its clothing becomes too tight until, having reached a length of almost 2 centimeters, he suddenly stops feeding and, having found a suitable place, hebegins to spin his silk web around him. Inside the cocoon it remains dormant for a while in the chrysalis state, and then the moth form emerges from its silken prison.
Pasteur proved that "the corpuscles may begin in the egg and escape detection, germinate in the worm and confuse the microscope." Like the. Feeding together, the body parts of the sick are transferred to the healthy worm, and the infected worm, without immediately showing signs of illness, can spin its cocoon and eventually lay eggs; but the eggs are all infected. Instead, then, as silk growers were wont to do, to select the eggs for the next year's growth from the moths which had most successfully survived their cocoons, the microscope was brought to bear on the moths when the presence of these diseased corpses without exception has been made clear.
This is a practice now adopted by all silk growers, and many women trained with the microscope examine each butterfly as it emerges from the cocoon. Here, then, we have the first distinct connection between living germs and the cause of disease, infection, and hereditary defects.
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They multiply quickly; the parent cell in the case of bacteria dividing into two or more new cells, and these again undergo subdivision. The tube is then placed under the best conditions for the growth of bacteria and excluded from the dust. Where a germ has fallen, a spot of mold will soon appear, and such spots mark the abode of the original single germ.
It seems not unlikely that these harmless people serve a useful purpose in perpetuating putrid change and acting as scavengers for the world's garbage; but the subject is still in its infancy, and one upon which no doubt fresh light will fall as bacteriological research progresses. The following table gives the ratio of dust particles, spores, etc., and bacteria in a cubic foot of town and country air:^.
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A RAPID METHOD FOR THE ESTIMATION OF CARBONIC ACID IN
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