400 THE COMPOSITION OF EXPIRED AIR. 



under stand the failures on the part of the other experimenters. They 

 emphatically reaffirm that the expired breath of man and animals con- 

 tains a volatile organic poison producing the results reported by them, 

 and that these results are not produced by excess of carbonic acid or 

 deficiency of oxygen in the air. 



From the foregoing summary of the reports of different experimenters, 

 it will be seen that widely different results have been reported by them, 

 but that the majority of tbe later investigators agree in denying that 

 the exhaled breath of healthy human beings or of animals contains a 

 poisonous organic alkaloid, or any poisonous product other than car- 

 bonic acid, yet in any case positive results require an explanation 

 which shall account for the facts. 



DR. BEEGEY'S EXPERIMENTS. 



The first experiments made by Dr. Bergey were to ascertain whether 

 the condensed moisture of air expired by man in ordinary, quiet respi- 

 ration contains any particulate organic matters, such as microorgan- 

 isms, epithelial scales, etc. The test for microorganisms was made by 

 having an adult man expire for from twenty to thirty minutes through 

 sterilized melted gelatin, which was then preserved as a culture for 

 from twenty to thirty days. In the first trial, six, and in the second, 

 two colonies of common air organisms developed; but when special 

 care was taken to thoroughly sterilize the vessels used, the result was 

 that in two consecutive trials the gelatin remained sterile, Erfithelial 

 scales and other particulate matters Avere sought for by condensing the 

 vapor of the exhaled breath and examining the product with the micro- 

 scope, with and without the use of stains. In six preparations thus 

 examined no bacteria or epithelial cells were found. This result was 

 to be expected, since neither bacteria nor wetted particles pass into the 

 air from the surface of fluids, or from moist surfaces, unless the air 

 currents are sufficiently powerful to take up particles of the liquid 

 itself in the form of spray. 



Abbott (30), in his paper on sewer gas, reports some experiments made 

 to determine the possibility of conveying microorganisms from liquid cul- 

 ture media by means of a current of air bubbling through such media; 

 also by means of ordinary baker's yeast inoculated into media contain- 

 ing from 4 to 5 rjer cent of glucose. No bacteria were carried from the 

 culture by the exploding air bubbles produced by the yeast, but a cur. 

 rent of air equal to 3£ liters in six hours, bubbling through a liquid 

 culture, carried with it some of the organisms in the culture. 



The determinations of ammonia in the condensed fluid of expired air, 

 the estimation of its reducing rjower upon solution of permanganate 

 of potash, and its reaction with various reagents, were made with fluids 

 collected from a healthy man, from a man with a tracheal fistula follow- 

 ing excision of the larynx, the expired air not coming in contact with 

 the mouth or the pharynx, and from a man suffering from well-marked 



