101 



water hath until thecontentsof the flask have evaporated to about 3 to 4 cc. Cool, trans- 

 fer by washing with water to a separatory funnel, so that the final volume does notgreatly 

 ex -e'ed L'O cc. Add four times the volume, or about 80 cc of chloroform, shake for some 

 time vigorously, allow to stand until the chloroform clears perfectly, pass through a 

 small dry filter into a dry 100 cc Erlenmeyer, distil off the solvent and use distillate 

 for a second extra* lion, observing the same method of shaking, clearing, and filtering 

 as above noted. Distil off chloroform to a small volume, transfer residue to a small 

 tared beaker, or crystallizing dish, by means of a few cubic centimeters of chloroform. 

 Allow to evaporate spontaneously, or if desired on a steam or hot-water bath to dry- 

 n. -, in the latter case partially covering the dish toward the end of operation with a 

 watch glass in order to avoid possible loss from "popping." Cool in desiccator and 

 weigh as caffein, dry alkaloid. a 



Acetanilid. 



First method. The acid solution remaining in the separator and containing anilin 

 sulphate is run into a 100 cc Erlenmeyer, the filter through which the chloroform 

 MHBed i v. ..-h'-d <>nce with a little water, allowing the latter to run into the separator. 

 Km - tin- latter thoroughly, adding the aqueous rinsings tothe acid solution. Now, 

 run in slowly and with constant agitation a standard solution of potassium bromid- 

 l.i ornate 6 to a faint but distinct yellow coloration. The number of cubic centimeters 

 eni ployed, multiplied by the value of 1 cc in terms of acetanilid, will give the amount 

 of acetanilid present. 



Second method. The acid solution aforesaid is treated with successive small por- 

 tion.s of sodium bicarbonate until an excess of this reagent is observed in the bottom 

 I the separator. Add 50 cc of chloroform and 15 to 20 drops of acetic anhydrid, shake 

 for some turn- \iirorou-ly, allow the chloroform to clear, then pass through the same 

 filter n-ed i'or the cam-in intou, 100 cc Erlenmeyer, and distil off most of the chloroform. 

 Use this distillate I >r a .-ec. >nd shake out, clear, filter, and distil down to a small vol- 

 ume. transferring the residue and t he subsequent chloroform washings to a tared beaker 

 >r di-h precisely as m the case of caffein. Allow the solvent to evaporate spontane- 

 u>l\ or by means of a bla.-t or fan, avoiding, however, undue heat. c Dry in desic- 

 >ver quicklime t" con-taut weight. 



nv the final wei-lit by means of titration with standard potassium bromid- 

 bromate solution as in t ho first method. Heat the residue with 10 cc dilute sulphuric 

 .i hall h'.ur on the steam or vapor bath, cool, add 5 cc of water and titrate as 

 1 above. 



Sodium bicarbonate. 



The residue left after the first treatment with chloroform is weighed when dry and 



v nearly the amount oi sodium bicarbonate present. It may be more 



accurately estimated by titrating with tenth-normal sulphuric acid, using congo red 



licaior. or it may "l- unite. I with dilute sulphuric acid arid weighed as sodium 



BUlpfa 



< alculate results in parts per 100. 



a Should the cat'fein not be colorless or nearly so, the residue is dissolved in about 

 11 necessary (in case oily matters are present), through a wet 



filter, the filtrate acidified with dilute hydrochloric acid, the caffein precipitated 

 with ream-lit, allowed to stand a half hour, filtered, and the 



.pilule washed with a lew cubic centimeters of same reagent, the filter, together 

 with precipitate. tran-iVrred to separator, decolorized by means ot sodium sulphite, 

 and the cat'fein finally extracted with chloroform. 



ft For this purple the solution is prepared by adding bromin in slight excess to a 

 concentrated aqueous >olutin of 50 grams caustic potash, the liquid diluted till the 

 separated salte redissolve, boiled, to expel any excess of bromin, and finally made 

 up to 1 liter. This solution is standardized with weighed amounts of acetanilid, or 

 it ma> be s.) adjusted by further dilution that 1 cc is exactly equivalent to 1 centi- 

 gram of acetanilid. Kor purposes of titration 1 to 2 decigrams are heated a half hour 

 on the steam or water bath with 10 cc of dilute sulphuric acid. 



c Acetanilid suffers appreciable loss when heated above 40. 



