164 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



the methyl mercaptan, discovered by Nencki among the gases 

 formed during putrefaction, is collected in the form of the 

 mercury mercaptide. This arrangement also helps materi- 

 ally to diminish the odor of putrefaction in the room in which 

 the experiment takes place. 



Digest about six days or even longer and then distil the 

 mixture, best from a large metal vessel. Measure the dis- 

 tillate. As soon as seven liters have distilled over pour 

 about 2.5 liters of water into the distillation vessel and 

 distil off the same amount. The indol, skatol, and phenol 

 pass over almost completely with the strongly ammoniacal 

 distillate. The distillate also contains besides hydrogen 

 sulphide or ammonium sulphide, ammonium carbonate and 

 ammonium bases small quantities of volatile fatty and 

 aromatic acids, while the greater part of these acids remains 

 in the distillation residue as the sodium salts. The method 

 of treatment of the distillate and of the distillation residue, 

 apart from some slight modifications, is the same as given 

 above, except that the isolation or purification of the products 

 can be carried further on account of the larger quantities of 

 the substances at command. 



(a) Distillate. 



1. To get rid of the disagreeable hydrogen sulphide it is 

 advisable to add some copper sulphate solution to the dis- 

 tillate and to filter from the copper sulphide. The aqueous, 

 fluid (B) (see scheme on page 159) is evaporated as before, 

 but, since it contains copper sulphate, it is advantageous to 

 distil the residue with sodium hydroxide solution, collecting 

 the ammonia and the other bases in hydrochloric acid, and 

 then evaporate the solution thus obtained. If no copper 

 sulphate has been used, this roundabout way may be dis- 

 pensed with. To isolate the ammonium bases, the residue 

 resulting is extracted in the usual manner with absolute alco- 



