MINERAL OE INOEGANIC POISONS 91 



and is contained in ' producer gas ' to the extent of about 

 23 per cent., in ' water gas ' about 44 per cent., in ' Dowson 

 gas ' 24 per cent., in ' coal gas ' from 6 to 11 per cent., and 

 is further also formed in the explosion without complete 

 combustion of fire-damp in mines, and is thus a constituent 

 of choke-damp. 



Toxicity. — Estimates as to the toxic proportion of carbon 

 monoxide in air vary, but according to some authorities 

 (Gruber and Hempel) it is less than 1 per cent. On this 

 account, and in consideration of the numerous technical 

 and domestic employments of the above-named gases, 

 a description of carbon monoxide poisoning is desirable. 

 But recorded cases of death amongst animals are very rare. 



Absorption and Effects. — Carbon monoxide is rapidly 

 absorbed by the pulmonary mucosa, and passes into the 

 blood stream in the form of carboxyhsemoglobin, a combina- 

 tion of the monoxide with hasmoglobin, which is more stable 

 than the oxygen compound (oxyhsemoglobin). It is there- 

 fore an exceedingly toxic compound, since the stability of 

 the carboxyhssmoglobin prevents oxygenation of the blood, 

 and poisoning in an atmosphere containing over 3 per cent. 

 is almost instantaneous. 



In smaller proportions there is vertigo, and loss of power 

 and muscular tremors. Eespiration is difficult, rapid, and 

 stertorous. The heart's action is intermittent, power over 

 the sphincters is lost, and death ensues in coma. 



Post-MoFtem Appearances. — The most notable post- 

 mortem appearance is the bright redness of the blood, 

 which gives a pink or violet froth, but the lesions are not 

 characteristic. 



Treatment in suspected cases such as of coal gas or 

 choke-damp poisoning will take the form of inhalation 

 of oxygen, in the hope of dissociating the carboxy- 

 hffimoglobin, by means of excess of oxygen. Electrical 

 treatment, the positive pole in the rectum and the negative 

 in the mouth, has been recommended as valuable for small 

 animals. 



Chemical Diagnosis. — The best test for carbon monoxide 



