The air of towns / by J.B. Cohen.

  • Cohen, Julius B. (Julius Berend), 1859-1935.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: The air of towns / by J.B. Cohen. Source: Wellcome Collection.

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    25 to 45 years by far the largest number (122) are due to phthisis, and the next largest number (38) to pneumonia. This high percentage of deaths from such diseases is characteristic of all large manufacturing centers. But we need not have recourse to these statistics to assure ourselves of the beneficial effects of fresh air. We have all experienced them. Statistics, however, emphasize the cumulative effect of imperceptible changes—an effect which you will all admit is sufficiently serious. There is such a thing known as cumulati ve poisoning. White lead, for example, taken iiiternally in minute quantities will in time produce the effect of a poisonous dose. Bad air is also an example of a cumulative poison. According to Professor Foster, the average individual inhales 2,600 gallons of air in twenty-four hours, or about 34 pounds by weight, as against 5J pounds of food, liquid and solid, or six times the weight of food. If we had to buy our air at so much a pound or pay rates on it at so much a cubic foot or gallon, we should take good care that it was not adulterated; for we distinguish fresh air as we do fresh butter from the second-rate article. There is, however, an important distinction between food and air regarded in this way. If the food we take is not quite as nourishing or as good as it should be, the digestive process is sufficiently adaptable to select the good and reject the bad; but the lungs are infinitely more delicate in structure and function, and we can not with impunity inhale a vitiated air and expect our lungs to select the pure and reject the impure without permanent injury to our breathing apparatus as well as to our whole body. Before passing to the subject of ^^Town air,’’ I should like you to grasp and keep well before you the idea that we are living at the bottom of a great ocean of air, that we are surrounded on all sides by matter invisible because composed of minute particles (separated by spaces which are big in comparison with the particles) but none the less material. That the air has weight was first demonstrated by Galileo about the middle of the seventeenth century. I will repeat his experiment: A glass globe (fig. 1), furnished with a brass stopcock is evacuated by the air pump, the stopcock closed and the vessel then carefully coun¬ terpoised. On opening the stopcock air rushes in with a hissing sound, and the balance now sinks at the arm to which the globe is sus¬ pended, thus showing that the air has weight. How, this invisible matter or gas is not a single gas, but a mixture of gases—mainly two. One of these gases is nitrogen, an inert gas, whose chief properties are negative. 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. This gas helps things to burn and supports life by consuming waste tissue and keeping up the animal heat. In these processes the