PUTREFACTION IN BLOOD. 49 



hydrogen was very abundant generally at first, but after 

 a time it did not appear so; on allowing the blood to 

 stand for a while, and then drawing air through it, the 

 lead became deeply coloured by the sulphuretted hy- 

 drogen. There was^ in fact, a solution of sulphuretted 

 hydrogen formed in the blood ; and as soon as the stream 

 was allowed to pass through it, the sulphur compound 

 was carried off. If, however, this were allowed to con- 

 tinue long, there was an excess of air, the sulphide of 

 lead became oxidized, and a white powder was formed, 

 which was sulphate of lead. It was strange how rapidly 

 this oxidation took place. I had occasion previously to 

 observe this rapid oxidation of sulphide of lead, in at- 

 tempting to retain a permanent coating of that substance 

 on the surface of lead pipes used for water. When the 

 coating was made, I found it converted into a white powder 

 in a day or two. 



The air was passed through the putrid blood for several 

 months, coming in contact immediately on leaving the 

 blood with the chloride of lead. The salt of lead when exa- 

 mined was found to contain organic matter and ammonia ; 

 but it was not found to have lost all its putrid gases. 

 It contained a very minute quantity of phosphoric acid. 

 Carbon and nitrogen were found in the lead salt : 

 I '4 per cent, of carbon. 

 0*54 per cent, of nitrogen. 

 These amounts are as loo to 38*5, instead of, as in albumen, 



TOO to 28-9. 

 We might at first infer from this that the ammonia is re- 

 moved with greater rapidity than the carbon, and that 

 there is not acid enough formed to retain it in the liquid ; 

 but this is not really the state of the case. The portion of 

 the vapour retained by the salt of lead does not contain all 

 the carbon which passed into it, whilst it contains nearly 

 all the nitrogen. It might also be argued that, as only a- 



SER. III. VOL. II. E 



