XXIX] DRUGS 357 



of sulphuric acid (1 to 10) and evaporate on the steam bath until the volume is re- 

 duced one half. Add 10 cc. of water and continue the digestion as before, then add 

 a second 10 cc. of water and evaporate to 5 cc. Transfer the residue with about 

 20 cc. of water to a small separatory funnel and extract with 15, 10 and 5 cc. of 

 chloroform, washing each extract with 5 cc. of water in a second separatory funnel 

 to recover traces of phenetidin sulphate possibly dissolved by the chloroform, 

 finally rejecting the latter since it contains all the salol not previously eliminated 

 during the digestion. 



Add the wash water in the second separatory funnel to the solution of phenetidin 

 sulphate in the first separatory funnel and proceed as directed under 7, beginning 

 with "Treat with successive small portions of solid sodium bicarbonate". 



15 Alkaline Hydrolysis Method. — Tentative. 



On a small, tared filter weigh out an amount of the sample to contain not more 

 than 0.10 gram of salol, exhaust.with chloroform as directed in 14, collect the sol- 

 vent in a small, lipped Erlenmeyer flask and evaporate the chloroform by means of 

 an air blast without heat. Add 10 cc. of 2.5% sodium hydro.xid solution and heat 5 

 minutes on a steam bath. Cool quickly to room temperature in running water to 

 prevent partial hydrolysis of the acetphenetidin. Transfer the liquid to a separa- 

 tory funnel with a minimum of water, then rinse out the flask with the first 20 cc. 

 portion of chloroform used in the extraction. Extract the alkaline solution with 

 three 20 cc. portions of chloroform, wash each portion in a second separatory funnel 

 with 5 cc. of water and pass the solution through a small, dry filter into a 200 cc. 

 Erlenmeyer flask. Designate the combined alkaline solution and washings as A. 

 Distil the combined chloroform extracts to about 5 cc. Transfer by means of a 

 little chloroform to a small, tared beaker or crystallizing dish, evaporate on a steam 

 bath with the aid of an air blast, cool and weigh the residual acetphenetidin at 

 intervals until the weight becomes constant. 



SALOL. 



16 Acid Hydrolysis Method. — Tentative. 



Subtract the weight of acetphenetidin, as determined in 14, from the combined 

 weight of the 2 ingredients determined in 14, to obtain the weight of salol. 



1 7 Alkaline Hydrolysis Method. — Tentative. 



Place the combined alkaline solutions. A, under 15, in a 500 cc. glass-stoppered 

 bottle, dilute with water to about 200 cc, run in from a burette an excess (about 

 45 cc.) of N/7 potassium bromid-bromate, add 10 cc. of concentrated hydrochloric 

 acid and shake 1 minute, then at inteivals for 30 minutes. Add 10 cc. of 15% potas- 

 sium iodid solution and shake at intervals for 15 minutes. Titrate the free iodin 

 with standard sodium thiosulphate solution (preferably N/7), previously standard- 

 ized against the N/7 bromid-bromate solution. One cc. of N/7 potassium bromid- 

 bromate is equivalent to 2.55 mg. of salol. From the number of cc. of the N/7 

 bromid-bromate solution used, calculate the amount of salol on the basis of 12 atoms 

 of bromin to 1 molecule of salol. 



ACETANILID AND SODIUM SALICYLATE IN MIXTURES. 

 18 PREPARATION OF SAMPLE AND SOLUTION.-TENTATIVE. 



Weigh an amount of the powdered sample equal to, or a multiple of, an average 

 unit dose, transfer to a separatory funnel containing 10 cc. of water and, for every 

 unit dose, add 0.10 gram of solid sodium bicarbonate. In the case of coated tablets 



