URINE: QUANTITATIVE ANALYSIS. 399 



moved from the urine to the absorption bottle and there retained 

 as iodoform. 



The contents of the absorption bottle should now be acidified with 

 concentrated hydrochloric acid/ and titrated with y^ sodium thio- 

 sulphate and starch as in the Messinger-Huppert method (see 

 below). 



2. Messinger-Huppert Method. 2 Place 100 c.c. of urine in a 

 distillation flask and add 2 c.c. of 50 per cent acetic acid. Connect 

 the flask with a condenser, properly arrange a receiver, attach a 

 terminal series of bulbs containing water and distil over about nine- 

 tenths of the urine mixture. Remove the receiver, attach another 

 and subject the residual portion of the mixture to a second distil- 

 lation. Test this fluid for acetone and if the presence of acetone 

 is indicated add about 100 c.c. of water to. the residue and again 

 distil. Treat the united acetone distillates with i c.c. of dilute (12 

 per cent) sulphuric acid and redistil, collecting this second distillate 

 in a glass-stoppered flask. During distillation, however, the glass 

 stopper is replaced by a cork with a double perforation, the glass 

 tube from one perforation passing to the condenser, while the bulbs 

 containing water, before mentioned, are attached by means of the 

 tube in the other perforation. Allow the distillation process to pro- 

 ceed until practically all of the fluid has passed over, then remove 

 the receiving flask and insert the glass stopper. Now treat the dis- 

 tillate carefully with 10 c.c. of a j\ solution of iodine and add 

 sodium hydroxide solution, drop by drop, until the blue color is dis- 

 sipated and the iodoform precipitates. Stopper the flask and shake 

 it for about one minute, acidify the solution with concentrated 

 hydrochloric acid, and note the production of a brown color if an 

 excess of iodine is present. In case there is no such excess, the 

 solution should be treated with ^ iodine solution until an excess 

 is obtained. Retitrate this excess of iodine with T \ sodium thio- 

 sulphate solution until a light yellow color is observed. At this 

 point a few cubic centimeters of starch paste should be added and 

 the mixture again titrated until no blue color is visible. This is 

 the end-reaction. 



Calculation. Subtract the number of cubic centimeters of -f^ 

 thiosulphate solution used from the volume of T \ iodine solution 

 employed. Since I c.c. of the iodine solution is equivalent to 



1 An excess of iodine is indicated by the development of a brown color. 

 ~ This method serves to determine both acetone and diacetic acid in terms of 

 acetone. 



