EXPERIMENTAL WORK. 19 



CONSTITUENTS OP CRUDE PYROLIQNEOUS ACID. 



In Table 5 are given the results showing the composition of the 

 aqueous portion or the crude pyroligneous acid produced by dry 

 distilling the black liquor. This aqueous portion of the distillate 

 retains in solution and suspension, tar, tar acids, phenols, acetates, 

 acetone, etc. Only (1) total free acid, calculated as acetic, (2) esters, 

 (3) acetone, and (4) methyl alcohol were determined in the aqueous 

 distillate. 



The crude acid is first distilled by heating to 140 C. with 10 cc 

 phosphoric acid, adding small portions of water and distilling until 

 all the acid is over. This distillate is made to volume and used for 

 the following determinations: 



Free acetic acid. Titrate 100 cc with standard sodium hydroxid, 

 using phenolphthalein as indicator. Boil for the end point on account 

 of any carbon dioxid present. 



Esters. Saponify 100 cc with excess of normal sodium hydroxid 

 with reflux condenser for two hours, and titrate back with normal 

 acid, using phenolphthalein as indicator. Run a blank with water. 

 Subtract the number of cubic centimeters previously found to be 

 required to neutralize the free acid, from the number of cubic centi- 

 meters of soda neutralized by the solution. The remainder is neu- 

 tralized by the esters present. One molecule of sodium hydroxid 

 (40 grams) equals one molecule of methyl acetate (74 grams). 



Acetone. Messinger's method: 1 Place 10 cc of the sample in a 500 cc 

 glass stoppered bottle. Add 25 cc of normal sodium hydroxid and 

 run in drop by drop 20 cc fifth-normal iodin. Let stand 15 minutes; 

 add 26 cc normal sulphuric acid. The iodin in excess of the amount 

 required to form iodoform (CHI 3 ) is then titrated with tenth-normal 

 sodium thiosulphate. Three molecules of iodin (761) equal one 

 molecule of acetone. 



Methyl alcohol. Zeisel method, as modified by Perkins and 

 applied to the analysis of pyroligneous acid by Striter and Zeidler: 2 

 Distill 10 cc of the sample with 30 cc hydriodic acid. Pass the 

 methyl iodid evolved through a train, the first flask of which contains 

 25 cc of 2 per cent potassium arsenite to free the methyl iodid from 

 iodin and hydriodic acid. Each of the second and third flasks 

 contains 20 cc alcoholic silver nitrate. The apparatus is filled with 

 carbon dioxid and the glycerin bath containing the distilling flask 

 heated up to about 125 to 127 C., or as high as possible without 

 causing the hydriodic acid to distill. All of the methyl iodid should 

 be over in 1 hour. Wash the contents of the silver nitrate bottles 

 into a beaker, make to 450 cc, acidify with nitric acid, heat one-half 

 hour and filter into a Gooch. Correct for the amount of methyl 



i Klar. Technologic dea Holzverko&lung, 1910, p. 364. Analyst,1904, g 9: 313. 



