EFFECTS OF RESPIRATION ON THE AIR. 403 



bonic acid, Hydrochloric acid, Binoxide and Peroxide of Nitrogen, Ammonia, 

 Chlorine, and Ozone. If introduced through a trachea! fistula, all of them 

 act as poisons. Finally Nitrogen, Hydrogen, and perhaps Carhu retted hy- 

 drogen, may he considered as indifferent gases, proving fatal when breathed 

 in a .state of purity, hy permitting the accumulation of Carbonic acid in the 

 blood, and by failing to supply oxygen. Cyanogen is another gas which has 

 an actively poisonous influence upon animals, when absorbed into the lungs; 

 its agency is of a narcotic character, but has riot been accurately investi- 

 gated. 



:'.'_'2. The respiration of pure Oxygen for short periods, 7 17 minutes iu 

 man, 1 produces no effect either on the rapidity of the pulse or upon the tem- 

 perature of the body, and scarcely any more of this gas is absorbed than 

 under ordinary circumstances, which, as Pfluger has shown, is owing to the 

 fact that arterial blood is charged normally with nine-tenths of the whole 

 amount of oxygen it can take up." In small chambers 3 the whole of the 

 oxygen is used up, but if the chamber be large, the amount of Carbonic 

 acid" produced proves fatal before the complete consumption of the Oxygen. 

 Thus Bert observed that when an animal was placed in an atmosphere of 

 pure Oxygen with no provision for the removal of the Carbonic acid elimi- 

 nated, death took place when the proportion of this gas amounted to 20 30 

 per cent,, though the quantity of Oxygen was still from 70 80 per cent. 

 When all the Carbonic acid eliminated was removed, 4 death occurred in 

 mammals when the amount of Oxygen had fallen to 2 per cent., and in 

 birds when it was reduced to between 3 and 4 per cent. He further found 

 that animals made to breathe Oxygen at a pressure of 5 or G atmospheres, 

 or which are exposed to ordinary air at a pressure of 20 atmospheres, fall 

 into violent convulsions, which last even after the pressure has been reduced 

 to the normal. It would therefore appear that the Oxygen in entering the 

 blood at this high pressure forms one or more compounds with some of its 

 constituents, acting like strychnia. Death is also caused by the inhalation 

 of several gases of an irritant character, such as Sulphurous, Nitrous, and 

 Muriatic acids; but it is doubtful how far they are absorbed, or how far their 

 injurious effects are due to the abnormal action which they excite in the 

 lining membrane of the air-cells and tubes. It cannot be doubted that 

 Miasmata and other morbific agents diffused through the atmosphere, are 

 more readily introduced into the system through the pulmonary surface 

 than by any other; and our aim should therefore be directed to the discovery 

 of some counteracting agents, which can be introduced in the same manner. 

 The pulmonary surface affords a most advantageous channel for the intro- 

 duction of certain medicines that can be raised in vapor, when it is desired 

 to affect the system with them speedily and powerfully; such is pre-eminently 

 the case with those Anaesthetic agents, ether and chloroform, whose intro- 

 duction into the various departments of Medical and Surgical practice con- 

 stitutes a most important era in the history of the healing art; also with 

 Mercury, 5 Iodine, Tobacco, Stramonium, etc., and it has recently been shown 



1 Naoumoff and Beliaieff, Robin's Journal de 1'Anatomie, 1875, p. 138. See also 

 Kowalewsky, in Travaux du laboratoire physiologique de I'Univ. Imp. a Kasan, 

 l ere ser. Kasan, 1869. 



2 This is difficult to reconcile with the statement made by M. Grehant (Co'mptes 

 Eendus, 1872, 19 Aout), that 100 c.c. of carotid blood of the dog contains when air 

 is breathed 1G.3 per cent, of oxygen, and when oxygen is breathed 23.3, and even 

 26.8 per cent. 



3 See account of Miiller's Experiments in Funke's Physiology, 1870, p. 284. 



4 Paul Bert, Art. Asphyxia, Nouv. Diet, de Med., t. iii. 



5 The beneficial results of the introduction of Mercury by inhalation, are strikingly 

 set forth in Mr. Langston Parker's Essay on the Treatment of Secondary, Consti- 

 tutional, and Confirmed Syphilis. 



