246 METHODS OF ANALYSIS [Chap. 



Conduct a blank determination upon 100 cc. of carbon tetrachlorid beginning 

 the blank at that point of the procedure immediately after the extraction and just 

 before the washings with sodium chlorid and sodium sulphate solutions. 



1 5 SUGARS.-TENTATIVE. 

 Proceed as directed under XVI, 15, 16 or 17. 



METHYL ALCOHOL. 



16 Trillal Method^.— Tentative. 



To 50 cc. of the sample add 50 cc. of water and 8 grams of lime and fractionate 

 by the aid of Glinsky bulb tubes. Dilute the first 15 cc. of the distillate to 150 cc, 

 mix with 15 grams of potassimn dichromate and 70 cc. of sulphuric acid (1 to 5), 

 and allow to stand for an hour with occasional shaking. 



Distil, reject the first 25 cc. and collect 100 cc. Mix 50 cc. of the distillate with 

 1 cc. of redistilled dimethylanilin, transfer to a stout, tightly stoppered flask, and 

 keep on a bath at 70°-80°C. for 3 hours with occasional shaking. Make distinctly 

 alkaline with sodium hydroxid solution, and distil off the excess of dimethylanilin, 

 stopping the distillation when 25 cc. have passed over. 



Acidify the residue in the flask with acetic acid, shake and test a few cc. by add- 

 ing 4 or 5 drops of 1% suspension of lead dioxid. If methyl alcohol is present, a 

 blue coloration occurs which is increased by boiling. 



Ethyl alcohol thus treated yields a blue coloration changing immediately to green, 

 later to yellow, and becoming colorless when boiled. 



1 7 Riche and Bardy Method^. — Tentative. 



The following method for the detection of methyl alcohol in commercial spirit 

 of wine depends on the formation of methylanilin violet : 



Place 10 cc. of the sample, previously redistilled over potassium carbonate if 

 necessary, in a small flask with 15 grams of iodin and 2 grams of red phosphorus. 

 Keep in ice water for 10-15 minutes until action has ceased. Distil off, on a water 

 bath, the methyl and ethyl iodids formed into about 30 cc. of water. Wash with 

 dilute alkali to eliminate free iodin. Separate the heavy, oily liquid which settles 

 and transfer to a flask containing 5 cc. of anilin. If the action be too violent, place 

 the flask in cold water; if too slow, stimulate by gently warming the flask. After an 

 hour boil the product with water and add about 20 cc. of 15% sodium hydroxid 

 solution; when the bases rise to the top as an oily layer, fill the flask up to the neck 

 with water and draw them off with a pipette. Oxidize 1 cc. of the oily liquid by 

 adding 10 grams of a mixture of 100 parts of clean sand, 2 of common salt, and 3 

 of cupric nitrate; mix thoroughly, transfer to a glass tube, and heat to 90°C. 

 for 8-10 hours. Exhaust the product with warm alcohol, filter and make up to 

 100 cc. with alcohol. If the sample of spirits is pure, the liquid has a red tint, but, 

 in the presence of 1% of methyl alcohol, it has a distinct violet shade; with 2.5% 

 the shade is very distinct, and still more so with 5%. To detect more minute quan- 

 tities of methyl alcohol, dilute 5 cc. of the colored liquid to 100 cc. with water, and 

 dilute 5 cc. of this again to 400 cc. Heat the liquid thus obtained in a porcelain 

 dish and immerse in it a fragment of white merino (free from sulphur) for 30 min- 

 utes. If the alcohol is pure, the wool will remain white, but, if methyl alcohol is 

 present, the fiber will become violet, the depth of tint giving a fairly approximate 

 indication of the proportion of methyl alcohol present. 



