14 THE COMPOSITION OF EXPIRED AIR. 



two colonies of common air organisms developed ; but w hen special care was taken 

 to tlioioughly sterilize the vessels used, the result was that in two consecutive tiials 

 the gelatin remained sterile. Epithelial scales and other particulate matters were 

 sought for by condensius: the vapor of the exhaled l)reatli and examininir the ino- 

 duct with the microsco[ie, with and without the uj^e of stains. In six pieparations 

 thus examined no bacteria oi- e^jithelial cells wei'e found. This I'esult was to be 

 expected, since neither bacteiia nnr wetted particles pass iiiti) the air from the sur- 

 face of fluids, or fiom moist surfaces, unless the air cnrients aie suHiciently power- 

 ful to take up particles of the liquid itself in the form of spray. 



Abbott (36), in his paper on "Sewer-Gas," leports some experiments made to 

 determine the possibility of conveying raicroorgani.sms frimi liquid culture media 

 V)y means of a current of aii- bubbling through such media; also by means of 

 ordinary baker's yeast inoculated into media containing from 4 to 5 per cent, of 

 glucose. No bacteria were carried from the culture by the ex[»lodiug air-bubbles 

 produced by the yeast, but a current of air ecpial to 33, lities 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 esti- 

 mation of its reducing power upon solution of penuanganate of potash, and its 

 reaction with various reagents (see Appendix, Section II.), were made with fluids 

 collected from a healthy man, from a man with a tracheal fistula following excision 

 of the larynx, the expired air not coming in contact with the mouth or the pharynx, 

 and from a man suffering fiom well marked tubei'culosis of the lungs. In each 

 case the amount of aiiniuinia and of albuminoid aniiiitmia in the fluid was veiy 

 small, as shown by Table B in the appendix, the average being, in grams per litre 

 of fluid : 



Healthy man 



Man with tracheal fistula . 

 Consumptive 



Albuminoid Ammonia. 



.o8i 



.00036. 



.0034. 



The oxidizable matter in these fluids, as shown by their reducing power on a 

 solution of permanganate of potash, was determined, and the details are given in 

 Table C in the appendix. The average results, stated in milligrammes of oxygen 

 consumed per litre of conden.sed fluid, are as follows: Healthy man, 10.72 ; man 

 with ti-acheal fistula, 13.49 ; consumptive, 19.34. The high average for the man 

 with the tracheal fistula is due to a single observation, for which the figure was 

 24.910. Omitting this, the average for the three other observations would be 9.G8. 



