10 THE COMPOSITION OF EXPIRED AIR, 



iiitii tlie subcutaneous tissue of the back. Six rabbits were thus iujeeted, each 

 with So c. c. of the fluid, witli no evident disturbance of health in any of them; 

 80 c. c. to a ial>l)it corresponds to a dose of al)<»ut 3 litres to a man. They also 

 repeated the e.xperiments of lirown-Secpiard and d'Arsonval in supplying to the 

 animals air charged with organic matter drawn directly from the lungs of other 

 animals. Two large rabbits were placed in an aii-tight chamber and a current of 

 air diawn tlirough this was sui)i)lied to two young rabbits under observation ; no 

 effect was produceil. 



Merkel, in 1892, (29), reported an experiment in which four airtight glass 

 vessels, of H litres capacity, were connected by means of glass tubes; a mouse 

 being placed in each vessel. Between the third and fourth vessels a Geissler 

 absoi'[)tion tube, containing sulphuric acid, was interposed. Air was now drawn 

 slowly thnnigh the vessels by means of an aspirator, so that the second mouse 

 breathed the air from the first, the third from that of the second, etc. The residt 

 was, just as in the experimeut of BrownSeipiard antl d'Arsonval, that the mouse 

 in tile thii-d vessel died first, after 16-20 hours, while that in the fourth vessel 

 remained alive. 



Tiie conclusion is drawn that, as the fourth mouse lemained alive, the death 

 of the thiid cannot have been due to excess of carbonic acid, i)r deficiency of 

 o.xygen in the air, but must have been caused by the presence of some volatile 

 substance which is absorbed or destroyed by sul[)huiic acid. 



The symptoms presented by the mice before death were at first restlessness 

 an<l gradually inci'easing acceleration of respiration, afterward slowing of respira- 

 tion, and finally spasmodic deep respirations, becoming constantly less frequent 

 until the advent of death. The proportion of carbonic acid in the air led through 

 the gla.ss vessels was not poisonous ; it amounted in the highest case to 1.5 per 

 cent. 



Merkel also conducted the expired breath through HCl with the idea of com- 

 bining the organic matter with it, and believed he was successful, but the quantities 

 of the "salts" produced Avere so small that determination of their chemical nature 

 was impossible. His experiments upon animals with this body, obtained from its 

 combination by neutralization of the acid, gave negative results. 



He concludes that the expired breath of healthy persons contains a volatile 

 poison in exti'emely small quantities ; l:)eing probably a base which is poisonous in 

 its gaseous state, but loses its toxicity aftei- comljination with acids. His belief 

 in the toxicity of the organic matter contained in the expired breath of human 

 beings is based solely upon the results he obtained in the " Brown-Scipiard and 

 d'Arsonval" experiment. 



