66 ALCOHOL. 



other there is a deep green, and then a lighter green, 

 colour produced. One fourth to one tenth of a grain 

 of alcohol in half an ounce of water will yet be indi- 

 cated by this test. Prove this by experiments with 

 pure alcohol. 



4. By the foregoing process you can prove the 

 presence of alcohol in from two to six ounces of urine 

 secreted a few hours after the drinking of spirituous 

 liquors. 



5. Quantitative determination of small quantities of 

 alcohol by transformation into acetic acid. Enclose 

 the distillate with a certain quantity of the dichromate 

 and sulphuric acid mixture in a strong flask, stop it 

 air-tight with a caoutchouc stopper, and tie it down 

 well by means of wire. Heat this flask for two hours 

 in a water-bath to between 80 and 90 C., never to the 

 boiling-point; then attach the flask to a condenser, 

 and distil the newly-formed acetic acid out of it. 

 Determine the acidity of the distillate by volumetric 

 analysis, with a standard solution of caustic soda. 



6. In case larger quantities of alcohol are contained 

 in the matters to be examined e. g. vomited matter, 

 contents of stomach or intestines, blood, brain, muscles, 

 or urine in quantity then the distillate can be con- 

 densed by successive distillations, in which one half of 

 the liquid is driven over every time, and the liquid in 

 the retort is each time mixed with common salt. 

 Ultimately the distillate will smell of alcohol, and burn 

 when exposed to flame. It can then be made anhy- 

 drous by boiling with and distilling from quicklime or 

 anhydrous copper sulphate. Its specific gravity at 



