146 CONTENTS OF THE INTESTINAL CANAL 



the presence of bile-pigment by nitric acid, and of the resinous 

 biliary acids, by Pettenkofer's test, in the alcoholic extract 

 when carefully prepared ; and this extract may usually be obtained 

 in considerable quantity. Every one who himself analyses such 

 stools is, at all events, led to the subjective conviction that a 

 part of the green and light colour may be dependent on bile- 

 pigment. To this we must add that Buchheim* has recently 

 convinced himself by experiments on dogs, provided with artificial 

 fistulous openings (made according to Schmidt and Bidder's di- 

 rections) between the gall-bladder and the external abdominal 

 walls, that the administration of calomel actually causes an 

 increased secretion of bile, as well as a more abundant secretion of 

 mucus. If, moreover, the administration of calomel is sometimes 

 not followed by green stools (and this is not very unfrequently the 

 case), the evacuations either retaining their normal colour, or pre- 

 senting the characteristics of special morbid processes, this must 

 not be regarded as presenting an argument against Merklein's view ; 

 for it is obvious that, when the intestinal canal is in an abnormal 

 state, the conditions may not always be present which are requisite 

 for the formation of sulphide of mercury. On the other hand, 

 this is as little in opposition to the view that the bile-pigment 

 takes part in the coloration, since there are various conditions 

 under which the action of calomel on the hepatic secretion may 

 be modified and entirely checked. 



The case is altogether different with the dark, often black, but 

 frequently also green coloured stools, which occur after the pro- 

 longed use of preparations of iron, or chalybeate mineral waters, 

 especially such as contain sulphate of soda with carbonate of 

 protoxide of iron. Kerstenf was the first to show that the green 

 colour of these excrements was due to sulphide of iron ; his only 

 error was that he ascribed the colour to the bisulphide, being led 

 astray by the analogy with the formation of prismatic iron pyrites, 

 Fe S 2 , (spear pyrites,) which, as is well known, is produced in 

 stagnating waters, when organic substances undergo putrefaction 

 in the presence of the oxides of iron and alkaline sulphates. In 

 three cases in which I analysed the green and black excrements of 

 persons who for a long time had taken the Marienbad waters at 

 their source, IJ found 3'163, 1'039, and 2-100f of proto- 

 sulphide of iron in the dry residue of the pulpy stools. 



* In a Private Communication. 



t Walther's u. Ammon's Journ. f. Chir. Tli. 3, S. 180. 



$ Goschen's Jahresber. Bd. 3, S. 42. 



