Miscellaneous Intelligence. 155 



II. In ordinary quiet respiration, no bacteria, epithelial scales, 

 or particles of dead tissue are contained in the expired air. In 

 the act of coughing or sneezing, such organisms or particles may 

 probably be thrown out. 



III. The minute quantity of ammonia, or of combined nitro- 

 gen, or other oxidizable matters found in the condensed moisture 

 of human breath, appears to be largely due to products of the 

 decomposition of organic matter which is constantly going on in 

 the mouth and pharynx'. This is shown by the effects of cleans- 

 ing the mouth and teeth upon the amount of such matters in the 

 condensed moisture of the breath, and also by the differences in 

 this respect between the air exhaled through a tracheal fistula 

 and that expired in the usual way. 



1Y. The air in an inhabited room, such as the hospital ward 

 in which experiments were made, is contaminated from many 

 sources besides the expired air of the occupants, and the most 

 important of these contaminations are in the form of minute par- 

 ticles, or dust. The experiments on the air of the hospital ward, 

 and with the moisture condensed therefrom, show that the greater 

 part of the ammonia in the air was probably connected with dust 

 particles which could be removed by a filter. They also showed 

 that in this dust there were micro-organisms, including some of 

 the bacteria which produce inflammation and suppuration, and it 

 is probable that these were the only really dangerous elements in 

 this air. 



V. The experiments in which animals were compelled to 

 breathe air vitiated by the products of either their own respira- 

 tion or by those of other animals; or were injected with fluid 

 condensed from expired air, gave results contrary to those reported 

 by Hammond, by Brown-Sequard and d'Arsonval, and by Merkel, 

 but corresponding to those reported by Dastre and Loye, Russo- 

 Giliberti and Alessi, Hoffmann-Wellenhof, Rauer, and other ex- 

 perimenters referred to in the preliminary historical sketch of 

 this report, and make it improbable that there is any peculiar 

 volatile poisonous matter in the air expired by healthy men and 

 animals, other than carbonic acid. It must be borne in mind, 

 however, that the results of such experiments upon animals as 

 are referred to in this report may be applicable only in part to 

 human beings. It does not necessarily follow that a man would 

 not be injured by continually living in an atmosphere containing 

 two parts per 1000 of carbonic acid and other products of respir- 

 ation, of cutaneous excretion, and of putrefactive decomposition 

 of organic matters, because it is found that a mouse, a guinea- 

 pig, or a rabbit seems to suffer no ill effects from living under 

 such conditions for several days, weeks, or months; but it does 

 follow that the evidence which has heretolore been supposed to 

 demonstrate the evil effects of bad ventilation upon human health 

 should be carefully scrutinized. 



VI. The effects of reduction of oxygen and increase of car- 

 bonic acid to a certain degree appear to be the same in artificial 



