408 OF RESPIRATION. 



scale ; there has happened one at no distant date, however, which rivalled 

 it in magnitude. On the night of the 1st of December, 1848, the deck 

 passengers on board the Irish steamer Londonderry were ordered below by 

 the captain, on account of the stormy character of the weather ; and although 

 they were crowded into a cabin far too small for their accommodation, the 

 hatches were closed down upon them. The consequence of this was, that 

 out of 150 individuals, no fewer than 70 were suffocated before the morning. 

 326. It cannot be too strongly impressed upon the Medical practitioner, 

 however, and through him upon the Public in general, that the continued 

 respiration of an atmosphere charged in a far inferior degree with the exhala- 

 tions from the Lungs and Skin, is amongst the most potent of all the " pre- 

 disposing causes" of disease, and especially of those zymotic diseases whose 

 propagation seems to depend upon the presence of fermentable matter in the 

 blood. That such is really the fact, will appear from evidence to be presently 

 referred to ; and it is not difficult to find a complete and satisfactory explana- 

 tion of it. For, as the presence of even a small percentage of carbonic acid 

 in the respired air is sufficient to cause a serious diminution in the amount 

 of carbonic acid thrown off and of oxygen absorbed ( 310), it follows that 

 those oxidating processes which minister to the elimination of effete matter 

 from the system, must be imperfectly performed, and that an accumulation 

 of substances tending to putrescence must take place in the blood. Hence 

 there will probably be a considerable increase in the amount of such matters 

 in the pulmonary and cutaneous exhalation ; and the uurenewed air will be- 

 come charged, not only with carbonic acid, but also with organic matter in a 

 state of decomposition, and will thus favor the accumulation of both these 

 morbific substances in the blood, instead of effecting that constant and com- 

 plete removal of them, which it is one of the chief ends of the respiratory 

 process to accomplish. It has been customary to consider the consequences 

 of imperfect respiration, as being exerted merely in promoting an accumula- 

 tion of carbonic acid in the system, and in thus depressing the vital powers, 

 and rendering it prone to the attacks of disease. But the deficiency of 

 oxygenation, and the consequent increase of putrescent matter in the body, 

 must be admitted as at least a concurrent agency ; and when it is borne in 

 mind that the atmosphere in which a number of persons have been confined 

 for some time becomes actually offensive to the smell in consequence of the 

 accumulation of such exhalations, and that (as will presently appear) this 

 accumulation exerts precisely the same influence upon the spread of zymotic 

 disease as that which is afforded by the diffusion of a sewer-atmosphere through 

 the respired air, it scarcely admits of reasonable doubt, that the pernicious 

 effect of overcrowding is exerted yet more through its tendency to promote 

 putrescence in the system, than through the obstruction it creates to the due 

 elimination of carbonic acid from the blood. For it is to be remembered, 

 that whilst the complete oxidation of the effete matters will carry them off by 

 the lungs in the form of carbonic acid and water, leaving urea and other 

 highly azotized products to pass off by the kidneys, an imperfect oxidation 

 will only convert them into those peculiarly offensive products which char- 

 acterize the fecal excretion ( 131 ).* 



1 It is a remarkable confirmation of Prof. Licbig's analogy between the imperfect 

 oxidation of effete matters within the body, and that combustion in a lamp or furnace 

 insufficiently supplied with air which causes a deposit of soot and various rmpyreumatie, 

 products, that a set of acids have been found by Stiideler in the urine of the cow, bear- 

 ing a close analogy to well-known products of destructive distillation, and one of them 

 actually identical with the carbolic acid previously known as one of the ingredients 

 of smoke. See Prof. Gregory's Handbook of Organic Chemistry, p. 450. 



