818 FOODS AND FOOD ADULTERANTS. 



METHODS OF ANALYSIS ADOPTED FOR WAX. 



Acid and ether numbers. These were determined by the well-known 

 method of Hehner (Analyst, 1883, 16, see abstracts, p. 844) using the 

 acidimetric values ar> determined by titration with alcoholic potash. To 

 set the potash and for back titration hydrochloric acid was used. This 

 was standardized by weighing portions and precipitating the chlo- 

 rine as silver chloride and weighing. This gave the per cent of hydro- 

 chloric acid by weight in the standard solution. The specific gravity 

 of the solution was then taken at various temperatures by a specific 

 gravity bottle, and from these two figures a table made out giving the 

 content of acid of* 1 cc at the prevailing temperatures. The method of 

 titration in detail was : 



Between 4 and 5 grams of wax were weighed and placed in a flask hold- 

 ing about 500 cc., covered with 100 cc of 95 per cent alcohol, a reflux 

 condenser attached, and the alcohol boiled vigorously for two hours. 

 While still hot it was titrated with alcoholic potash, using phenol- 

 phtalein as an indicator. A cubic centimeter of normal potash solution 

 is equivalent to 410 milligrams of cerotic acid. Into the same flask 

 were now run 50 cc of approximately half-normal alcoholic alkali, the 

 condenser reinserted, and the alcohol heated to a brisk boil for five 

 hours. The excess of alkali was then titrated by standard hydrochloric 

 acid and the number of cubic centimeters required deducted from the 

 number of cubic centimeters required to neutralize the potash in a 

 blank which had received exactly the same treatment, except, of course, 

 the addition of wax. The alkali which had disappeared was equivalent 

 to the number of cubic centimeters of the standard hydrochloric acid 

 thus obtained. One cubic centimeter of normal acid is equal to 076 

 milligrams of myricin. 



Melting points. Melting points were done by dipping the bulb of a 

 thermometer into the melted wax for an instant, placing the thermom- 

 eter (which now carried a thin film of wax on the bulb) through a 

 perforation in the cork of a wide bottle, hanging the bottle in a beaker 

 full of water kept heated to about 65, and noting the temperature 

 shown by the thermometer at the instant the wax runs down the bulb 

 and forms a hanging drop. This was called the melting point. The 

 experiment was tried of allowing the wax to remain on the bulb over 

 night before making the determination, but the melting point did not 

 differ from that shown by a fresh wax coating. 



Iodine number. This was determined according to the conventional 

 method (Hiibl's) for fats, except that owing to the low numbers found 

 a greater weight (2 grains) was taken than is usual for fats (0.2 to 1.0 

 gram). More chloroform was also required. The method in detail is: 



Two grams were weighed and placed in a glass-stoppered flask and dis- 

 solved in 40 cc of chloroform. Twenty-five cc of an iodine solution (con- 

 taining 25 grams iodine and 30 grams of mercuric chloride dissolved in 

 95 per cent alcohol and made up to 1 liter) were then run in and the mix- 



