DETECTION AND DETERMINATION OF ALCOHOLS, ETC. 3 



distilling it, using an ordinary distilling flask, from 94 to 100 per cent 

 of the total alcohol could be easily concentrated in a relatively small 

 volume of distillate, as is shown from the following experiments 

 selected from a number made to test this point : 



Experiment 1. To 500 cc of water containing 1 gram of absolute 

 alcohol (0.2 per cent by weight) there were added 200 grams of calcium 

 chlorid and this solution was distilled from a 1 liter distilling flask, 

 150 cc of distillate being collected. To this distillate there were added 

 50 grams of calcium chlorid and a 50 cc solution was distilled from it. 

 This distillate gave at 17.5 C., with the Zeiss immersion refracto- 

 meter, a reading of 18.2, equivalent to 2 per cent of alcohol, a 100 per 

 cent recovery. 



Experiment 2. Five hundred cubic centimeters of 0.19 per cent 

 alcohol were treated as in experiment 1, save that of the first distillate 

 but 100 cc were collected. The refractometer reading at 17.5 C. was 

 17.9, equivalent to 1.84 per cent alcohol, a 96.8 per cent recovery. 



Experiment 3. This experiment was conducted exactly as in the 

 case of No. 2. except that instead of using calcium chlorid, the solu- 

 tions were about three-fourths saturated with common salt. The 

 refractometer reading was 17.9 at 17.5 C., equivalent to 1.84 per 

 cent alcohol, a 96.8 per cent recovery. 



Experiment 4- From the distillates of experiments 2 and 3 (100 cc 

 of 1.84 per cent alcohol) after three-quarters saturation with salt, 

 there were distilled 50 cc. The refractometer reading at 17.5 C. was 

 21.0, equivalent to 3.71 per cent alcohol (theory 3.68 per cent), a 

 100.8 per cent recovery. 



Experiment 5. Five hundred cubic centimeters of 1.6 per cent 

 alcohol were treated as in experiment 3. The refractometer reading 

 at 17.5 C. was 42.7, equivalent to 15.02 per cent alcohol, a 94 per cent 

 recovery. 



Experiment 6. One thousand cubic centimeters of 0.1 per cent 

 alcohol were three-quarters saturated with salt, l50 cc were dis- 

 tilled off, again three-fourths saturated with salt, and from this solu- 

 tion 25 cc were distilled which at 17.5 C. had a refractometer reading 

 of 21.3, equivalent to 3.84 per cent alcohol, a 96 per cent recovery. 



These experiments prove that very small percentages of alcohol 

 may easily be concentrated from salt solutions to a strength that can 

 be used for the accurate determination of alcohol by known methods. 

 The method here proposed for detecting and determining small quan- 

 tities of alcohol is as follows: 



Using the methods outlined in the preceding experiments con- 

 centrate the sample until a solution containing from 2 to 4 per cent 

 of alcohol is obtained. If acids are present in the original solution 

 exactly neutralize before distilling, using a trace of solid phenol- 

 phthalein as an indicator. Treat the final distillate as follows : Deter- 



