THE LUNG PLAGUE OP CATTLE. 79 



absolute seclusion is rarely required, and that a certain amount of aerial 



diffusion is always .n'oing on through imperfectly closed hatches, com- 

 panion ways, and ventilators, yet that these arc often insiiHicicnt ha> 

 been amply shown by such losses as an- reported above, as well as by 

 the bronchitis and tuberculosis which Drs. Whitney, Lyinan, and \Vii- 

 liams have found in the lungs of American animals atidying in Kngland. 



ORGANIC MATTER IN EXPIRED AIR. 



The decomposing organic matter given off by tin 1 lungs and skin is 

 probably the most injurious of the animal excreta, when allowed to act 

 on the system for a length of time. This exhaled organic matter is 

 easily recognized in the air by chemical tests, or by the putrid odor 

 evolved when cotton wool that has been breathed through is left to soak 

 in otherwise pure water at a temperature of 70 to 80 Fahrenheit. 

 The experiments of Gavarret and Hammond, in which expired air had 

 its carbonic acid and water vapor removed, leaving only the organic 

 matter, showed that the latter was highly deleterious. Hammond 

 found that a mouse died in forty-five minutes in such an atmosphere. 

 It has also been again and again demonstrated that air containing a 

 given amount of carbonic acid as the result of respiration is far more 

 poisonous than air which contains the same amount of carbonic acid as 

 a product of combustion. 



WATER VAPOR IN EXPIRED AIR. 







The amount of water vapor given off by the lungs varies greatly ac- 

 cording as the air is already more or less saturated with water. As the 

 air in the stalls between decks is always saturated with water vapor, we 

 may take the very lowest estimate for each animal, namely, 60 ounces 

 in 24 hours, which for a cargo of 200 head would amount to over 93 gal- 

 lons. And this is in addition to the exhalations from the skin and the 

 bowel and kidney excretions. The air between decks is therefore con- 

 stantly saturated with moisture which condenses and runs down in 

 streams on every solid object. Among the ill effects of this saturation 

 may be noted : 



First. The saturation of the air with water vapor increases the exha- 

 lation of carbonic acid from Ihe lungs. This effect on the excretion of 

 carbonic acid is usually so great as to counterbalance the tendency of 

 warm air to reduce the production of this acid. This saturation, the're- 

 fore, with water increases the danger of suffocation by the accumulation 

 of the irrespirable carbonic acid in the ship, unless the air is being con- 

 stantly removed. 



Second. The excess of moisture in the warm atmosphere hastens the 

 decomposition of the organic matter derived from the lungs, skin, and 

 manure. Speaking of filth ferments, Simon says : " They show no power 

 of diffusion in dry air, but as moisture is their normal medium, currents 

 of humid air can doubtless lift them in their full effectiveness." Sir 

 Alexander Armstrong, head of the medical department of the British 

 Navy, says: a There can be no more fertile source of disease among 

 seamen, or, indeed, other persons, than the constant inhalation of a 

 moist atmosphere, whether sleeping or waking ; but particularly is this 

 influence injurious when the moisture exists between a ship's decks, 

 where it may be at the same time more or less impure, and hot or cold, 

 according to circumstances." It has become an aphorism with sanita- 

 rians that "a damp ship is an unhealthy ship," and many instances are 



