PHENOLIC DISINFECTANT. 59 



late the heat so that the condensing liquid will not be forced to the top of the 

 condenser. In this way the contents of the flask can be boiled without ap- 

 parently losing any of the solvent. Boil for thirty minutes. Cool, add phenolph- 

 thalein, and titrate the excess of potassium hydroxid with half-normal sulphuric 

 acid. On adding the acid the liquid separates into two layers and the change in 

 color can be seen in the lower layer ; the titrating, however, must be conducted 

 slowly. Subtract the cubic centimeters of sulphuric acid from the amount 

 used on blanks and calculate the saponiflcation number. For all practical pur- 

 poses 195 may be considered as the saponiflcation number of the fatty oils 

 used in lubricating oils, and hence if S equals the determined saponification 

 number, 100 S divided by 195 equals the percentage of fatty oil present. 



When the oil is very dark, or when soaps are present, it may be necessary 

 to determine the hydrocarbon oils directly. For this purpose saponify as de- 

 scribed, cool, add 25 cc of benzol, transfer to a separatory funnel, add 100 cc of 

 water, shake, allow to settle, draw off the water layer, and wash the benzol 

 three times with 100 cc of water; wash the soap solution with three portions 

 of 50 cc of benzol, evaporate off the benzol solution, and weigh the nonvolatile 

 hydrocarbon oils. 



12. Acid Number. 



See linseed oil, page 12. 



13. Bosin Oil. 

 See linseed oil, page 13. 



PHENOLIC DISINFECTANT. 



The phenolic soap mixtures can generally be identified as they form an 

 emulsion with water. They consist of phenolic soaps and hydrocarbon oils 

 and are quite variable in composition. The following scheme for analysis is 

 only a slight modification of that given by Allen. The only important modi- 

 fication consists in the recovery of light hydrocarbons, which by Allen's process 

 would be lost. 



1. Volatile Hydrocarbons. 



Mix the sample thoroughly, weigh a portion of somewhat more than 100 grams 

 in an Erlenmeyer flask with a funnel. Pour about 100 grams into a distilling 

 flask of 150 to 200 cc capacity, using the funnel to prevent the disinfectant 

 from getting on the neck of the flask, weigh back the Erlenmeyer flask and 

 the funnel, and get the exact weight by difference. The delivery tube of the 

 distilling flask should be bent so that it can connect with a small vertical con- 

 denser; all connections are of cork. Heat the flask in a paraffin bath, slowly 

 and carefully, not exceeding 130 C., for one and one-half hours, or until the 

 substance becomes solid or ceases to give off volatile matter. The receiver is a 

 small separatory funnel with a short tube, the tube of the condenser being con- 

 nected with it by a cork having a groove cut into it for the free passage of air. 

 The funnel is weighed empty, and again with the total volatile liquid; then the 

 water is drawn off and the remaining liquid weighed as volatile hydrocarbon. 



2. Pyridin. 



Dissolve the residue in the distilling flask in water, it is usually necessary 

 to add 60 cc of water ; heat slowly to avoid foaming and leave the flask in the 

 steam bath for about an hour. Wash the soapy solution into a 500 cc separa- 



a Commercial Organic Analysis, 3d ed., 2(2): 262. 



