200 



ACCIDENTAL IMPURITIES OF THE AIR. 



Ciliated JZ~^ 

 Epithelium. 



Clear disc. 



pound with the haemoglobin (1) CO ( 16 and 17). (2) CNH (hydrocyanic acid) displaces (?) 

 O from haemoglobin, forming a more stable compound, and kills exceedingly rapidly. Blood- 

 corpuscles charged with hydrocyanic acid lose the property of decomposing hydric peroxide into 

 water and ( 17, 5). 



(6) Narcotic Gases. (1) CO,. V. Pettenkofer characterises atmospheric air containing 'lper 

 cent C0 2 as " bad air" ; still, air in a room containing this amount of C0 2 produces a disagreeable 

 feeling, rather from the impurities mixed with it than from the actual amount of CO, itself. 

 Air containing 1 per cent. (J0 2 produces decided discomfort, and with 10 per cent, it endangers 

 life, while larger amounts cause death, with symptoms of coma. (2) N 2 (nitrous oxide), respired, 

 mixed with volume 0, causes, after 1 to 2 minutes, a short temporary stage of excitement 

 (" Laughing gas" of H. Davy), which is succeeded by unconsciousness, and afterwards by an 

 increased excretion of C0 2 . (3) Ozonised air causes similar effects (Binz). 



(c) Reducing Gases. (1) HS (sulphuretted hydrogen) rapidly robs blood-corpuscles of O, 

 S and H 2 being formed, and death occurs rapidly before the gas can decompose the haemoglobin 

 to form a sulphur-methaemoglobin compound. 



(2) PH 3 (pnosphuretted hydrogen) is oxidised in the blood to form phosphoric acid and 

 water, with decomposition of the haemoglobin. 



(3) AsH 3 (arseniuretted hydrogen) and SbH 3 (antimoniuretted hydrogen) act like PH 3 , but 

 the haemoglobin passes out of the stroma and appears in the urine. 



(4) CoNj (cyanogen) absorbs 0, and decomposes the blood. 



III. Irrespirable gases, i.e., gases which, on entering the larynx, cause reflex spasm of the 

 glottis. When introduced into the trachea, they cause inflammation and death. Under this 

 category come hydrochloric, hydrofluoric, sulphurous, nitrous, and nitric acids, ammonia, 

 chlorine, fluorine, and ozone. 



136. ACCIDENTAL IMPURITIES OF THE AIR. Amongst these are dust-particles, which 

 occur in enormous amount suspended in the air, and thereby act injuriously upon the respiratory 

 organs. The ciliated epithelium of the respiratory passages eliminates a large number of them 

 (fig. 148). Some of them, however, reach the air- vesicles of the lung, where they penetrate the 



epithelium, reach the interstitial lung- tissue 

 and lymphatics, andso pass with the lymph- 

 stream into the bronchial glands. Particles 

 of coal or charcoal are found in the lungs 

 of all elderly individuals, and blacken the 

 alveoli. In moderate amount, these black 

 particles do not seem to do any harm in the 

 tissues, but when there are large accumu- 

 lations they give rise to lung-affections, 

 which lead to disintegration of these organs. 

 [In coal-miners, for example, the lung- 

 tissues along the track of the lymphatics 

 and in the bronchial glands are quite black, 

 constituting " coal-miners' lung."] In 

 many trades various particles occur in the 

 air ; miners, grinders, stone-masons, file-makers, weavers, spinners, tobacco manufacturers, 

 millers, and bakers suffer from lung affections caused by the introduction of particles of various 

 kinds inhaled during the time they are at work. 



Germs. There seems no doubt that the seeds of some contagious diseases may be inhaled. 

 Diphtheritic bacteria (Bacillus diphtherias) become localised in the pharynx and in the larynx 

 glanders in the nose measles in the bronchi whooping-cough in the bronchi hay-monads 

 in the nose the Bacillus pneumoniae of pneumonia in the pulmonary alveoli. Tuberculosis, 

 according to R. Koch, is due to the introduction and development of the Bacillus tuberculosis 

 in the lungs, the bacillus being derived from the dust of tuberculous sputa. The same seems to be 

 the case with the Bacillus of leprosy and with Bacillus malariae, which is the cause of malaria. 

 The latter organism thus reaches the blood ; it changes the Hb within the red blood-corpuscles 

 into melanin ( 10, 3), and causes them to break up. The Micrococcus vaccinae of smallpox 

 gains access to the blood in the same way, also the Spirillum of remittent fever (fig. 23), the 

 microbe of scarlet fever, &c. 



Seeds of disease passing into the mouth along with air, and also with the food, are swallowed, 

 and undergo development in the intestinal tract, as is probably the case in cholera (Comma- 

 bacillus of B. Koch), dysentery, typhoid, and anthrax which is due to Bacterium anthracis 

 (fig. 24). 



137- VENTILATION OF ROOMS. Fresh air is as necessary for the healthy as for the sick. 

 Every healthy person ought to have a cubic space of at the very least 800 cubic feet, and every 

 sick person at the very least 1000 cubic feet of space. [The cubic space allowed per individual 

 varies greatly, but 1000 cubic feet is a fair average. If the air in this space is to be kept sweet, 



Inner layer. 



Fig. 148. 

 Ciliated epithelium. 



