30 TECHNICAL DRUG STUDIES. 



made from it, which would test* as above, yet it would not fairly represent an average 

 product. 



WILLIAM F. JOBBINS, (INC.). 



Definite, fixed limits of impurities should be prescribed and taste and odor tests 

 eliminated, as two different individuals almost invariably have a widely different 

 sense of taste or smell. One chemist will sometimes be of opinion there is a foreign 

 taste or smell, while another can detect neither. 



As the glycerin industry throughout the world has been revolutionized by our 

 patented processes and machinery, which have gradually been adopted during the 

 last past 15 years, and are now almost exclusively used by glycerin producers, we 

 submit we speak as recognized authorities on the subject, and beg to suggest that 

 the Pharmacopoeia requirements be changed, as follows: 



Specific gravity not less than 1.258 at 15 C. (60 F.), the specific gravity to be 

 ascertained by means of a Westphal specific gravity balance, all materials being at 

 the temperature of the room, the value found being reduced to the value at 15 C. by 

 adding a product represented by (temperature 15) X 0.000581. 



Carbonaceous residue, including mineral and readily carbonizable impurities, not to 

 exceed 0.009 per cent. Test: Weigh 50 grams of glycerin in a tared platinum dish, 

 heat cautiously until it inflames, then remove the source of heat (preferably Bunsen 

 burner) and allow the glycerin to burn away in a place free from draft; transfer the 

 dish to a desiccator and when cool weigh. 



Ash, including chlorids, not to exceed 0.005 per cent. Test: Ignite the carbona- 

 ceous residue at a red heat till it ceases to lose weight; then transfer to a desiccator 

 and when cold weigh. 



Chlorids, not to exceed 0.001 per cent, figured as NaCl. Test: Put the ash in 100 

 cc distilled water, make slightly acid with HNO 3 , add two or three drops of a cold, 

 saturated solution of neutral chromate of potassium as indicator, then run in from 

 accurately calibrated burette one-tenth normal silver nitrate volumetric solution till 

 tinge of permanent red color appears. The cubic centimeter of one-tenth normal 

 silver nitrate volumetric solution used multiplied by 0.005806 for each cubic centi- 

 meter, and then by 2, giving the percentage of chlorin as sodium chlorids. 



Total acid equivalent, in terms of NaOH, not to exceed 0.02 per cent. Test: 

 Weigh 100 grams of the glycerin, add 100 cc of distilled water and a few drops of 

 phenolphthalein solution as indicator. Run in an excess of one-tenth normal NaOH 

 solution (3.976 grams of NaOH to 1 liter) from a burette, boil for three minutes over 

 Bunsen burner, then titrate with tenth normal H 2 S0 4 solution (4.8675 grams per liter) 

 run in from a burette, until pink color just disappears. The NaOH solution used, 

 less the H 2 SO 4 solution used, must not exceed 5 cc to neutralize. 



In addition to the foregoing tests an aqueous solution (1 cc of glycerin to 10 cc of 

 distilled water) with 5 cc of tenth-normal silver nitrate volumetric solution, the mix- 

 ture shaken and placed in a dark place for 10 minutes, may assume a slight pink or 

 gray tinge, but must not turn red nor black, nor give a precipitate. The glycerin shall 

 then be considered chemically pure and free from chlorids, acids, or other impurities. 



These tests cover all possible impurities to be found in C. P. glycerin, and being set 

 forth with definiteness leave no latitude for controversy between chemists, and insure 

 a glycerin of such purity as is applicable in the use of medicines, foods, or drugs, and 

 are requirements which no honest refiner of glycerin can possibly make objection to, 

 and are, in fact, the tests by which the leading glycerin refiners are governed. 



American glycerin is equal to any foreign glycerin. Regarding test with Fehling's 

 solution, we have to say that same is no longer employed. If adulterated with sugar 

 it would increase the carbonaceous residue beyond the recognized limit, so sugar 

 adulteration is provided against by the carbonaceous residue test. 



