142 INFECTIONS OF THE DIGESTIVE TRACT 



color resulting from the action of the dimethylamido- 

 benzaldehyde on skatol, one obtains an amorphous blue 

 material which can be partially purified from the ad- 

 mixture with Ehrlich's aldehyde by the use of petroleum 

 ether. The nature of this compound is not at present 

 known. The melting point of our preparation lay be- 

 tween 65 C. and 66 C. 



The method of separating indol and skatol here de- 

 scribed has been used in a routine way during the past 

 year in connection with the study of the faeces and has 

 given satisfaction. To twenty-five grams of the mate- 

 rial have been added twenty cubic centimeters of water 

 and one to two cubic centimeters of a ten per cent, 

 sodium hydroxide solution. The suspension is then 

 subjected to distillation with the aid of steam, until the 

 distillate no longer gives a color reaction when boiled 

 with the dimethylamidobenzaldehyde solution. Ordina- 

 rily the indol and skatol present go over completely within 

 an hour, but where the material develops frothing a more 

 prolonged distillation may be necessary. When the 

 distillate has been obtained, it is treated in the manner 

 above outlined for the separation of indol and skatol. 

 In some cases one obtains only skatol from the faeces, 

 but as a rule indol is also present. In the presence of 

 indol the chloroform extract, instead of being a pure 

 blue, may have a slightly purplish tinge, owing to una- 

 voidable admixture with a slight amount of indol. 



It is important in making the colorimetric estimations 

 of the quantity of skatol present to employ a standard 

 color solution for comparison with the color obtained 



