THE NEW YORK JOURNAL OF PHARMACY 



11 



evident are so marked. However, it 

 must be remembered that an apparent 

 increase of concentration, owing to 

 quantitative disturbances by the pre- 

 servative, may be compensated by the 

 loss of material, owing- to fermentation 

 and other causes. Therefore, when 

 both factors are operative, the appar- 

 ent reading of concentration may be 

 above, equal to, or below the original 

 concentration, but is invariably above 

 the true concentration. 



Since chloroform yields formic and 

 hydrochloric acids by hydrolysis after 

 standing, its presence vitiates chlorine 

 and glucose determinations. Other 

 preservatives that destroy the accur- 

 acy of glucose are gallic acid, phenol, 

 salicylic acid, formaldehyde, hydrogen 

 peroxide, and thymol.^ 



Since thymol also absorbs iodine 

 and reduces alkaline picrate solutions, 

 its presence will effect not only the 

 glucose, but also the uric acid and 

 creatinine determinations. Owing to 

 hydrolysis, sulfuric acid, in dilute con- 

 centrations, converts creatine into 

 creatinine; in greater concentrations 

 sulfuric acid precipitates the creatin- 

 ine. For these reasons sulfuric acid 

 gives the abnormal results indicated 

 above. All concentrations of sulfuric 

 acid not only effect the creatinine but 

 precipitate the uric acid and most of 

 the coloring matter of urine. 



Adequate explanations of the other 

 high results in the tables are impos- 

 sible at present. 



*for the effect of formaldehyde on Feh- 

 ling's solution see Rudd and Bolenbaugh, 

 Proc. Virginia Chemists' Club, 220. 



^For the effect of thymol on acetone see 

 Welker, /. Biol. Chem., 3, 27; A^. Y. Med. J., 

 86, 552. 



Changes in Urine. — The changes 

 possible in urine through aging and 

 standing with preservatives are almost 

 as numerous as the components of the 

 mixture. Only certain inorganic salts, 

 as for instance sodium chloride, seem 

 proof to chemical decomposition. The 

 easiest observed changes result from 

 mere cooling, when urates and other 

 substances are precipitated. A change 

 in reactivity, as when normally acidic 

 urine become alkaline, is accompanied 

 by numerous chemical transformations, 

 particularly of the urate, the phos- 

 phate, and the creatine-creatinine equil- 

 ibria. For this reason it is evident 

 that an acid preservative most often 

 will be the more desirable. 



Important transformations in urine 

 are produced bacterially on glucose, 

 urea and other fermentable substances. 

 The enzymes developed are chemical- 

 ly hydrolytic, dissociative and oxida- 

 tive, as evidenced by the formation of 

 alcohol, carbon dioxide, ammonia, nit- 

 rate and nitrate. Though each of the 

 preservatives in the above studied con- 

 centrations, undoubtedly has inhibitory 

 influence, none has perfect bactericidal 

 power, hence none is a perfect preserv- 

 ative. 



Reference to the above data shows 

 very little change in the phosphates, 

 except when the reaction of the solu- 

 tion becomes neutral or alkaline ; a 

 notable exception is the ether sam- 

 ple. The chlorine analyses are uni- 

 formly constant, except when inter- 

 fered with by such preservatives as 

 hydrochloric acid, hydrogen peroxide, 

 and chloroform ; why the boric acid 

 sample is high is not evident. With 

 glucose the compensating influence of 



