GREEN STOOLS. 147 



The watery extract of these excrements contained much sul- 

 phate of protoxide of iron, which seemed to increase in proportion 

 to the length of time during which they were digested with 

 water and exposed to the air. The residue of these excrements, 

 which was insoluble in water, alcohol, and ether, developed sul- 

 phuretted hydrogen when treated with hydrochloric acid, and the 

 acid filtered fluid gave distinct indications of iron with all the 

 ordinary reagents. I now separated the residue insoluble in 

 water, alcohol, and ether, into three parts ; from one I extracted 

 the iron with hydrochloric acid, treated the solution with chlorine, 

 and determined the peroxide of iron quantitatively by precipitating 

 it with caustic ammonia; the second part I treated with aqua 

 regia, and determined the iron and sulphuric acid from the 

 solution ; while I incinerated the third part with carbonate and 

 nitrate of soda : by these means I found that the iron stood to 

 the sulphur in about the ratio of 28 : 16, which obviously corre- 

 sponds to the protosulphide. 



It has been doubted whether the sulphide of iron, even in the 

 state of finest comminution, can give rise to a green colour ; but 

 we may very easily convince ourselves on this point by adding a 

 proto-salt of iron to albumen, dissolving the precipitate by an 

 alkali, and passing a current of sulphuretted hydrogen through the 

 solution, or by adding a liver of sulphur.* There is then no pre- 

 cipitate, but the previously colourless fluid becomes of an intense 

 steel-green colour from the sulphide of iron which is formed. 



The alcoholic extract of these excrements, which was of a very 

 faintly yellow colour, contained neither bile-pigment nor the 

 resinous biliary acids ; but in the ethereal extract, there was, in 

 addition to fat, a substance which yielded the most distinct reaction 

 on the addition of sugar and sulphuric acid. 



In the ethereal extract, which ranged from 6 to 16% of the 

 dried excrements, there were contained not only margarin and 

 olein, but also butyric acid, and probably some other acids of the 

 same group. In the dry excrements there were contained from 

 22 to 24-g- of substances soluble in alcohol, from 14'5 to 18'7& of 

 substances soluble only in water, and from 16*6 to 26*8^ of in- 

 soluble matters (remains of food, mucus, &c.) The mineral sub- 

 stances in these excrements, after drying, ranged from 18*4 to 

 27'8, of which from 3'04 to 4'67-g- was sulphate of soda. 



Many vegetable substances likewise communicate a more or 

 less green or black colour to the excrements. The stools are often 

 * [This terra includes all soluble metallic sulphides. G. E. D.] 



L 2 



