EXAMINATION OF HYDROGEN DIOXID SOLUTIONS. 21 



all of the hydrogen peroxid manuiai -inn-d during the entire year is 2.31 cc tenth-normal 



KOI I, tested urronlilitf to the I'. S. P. 



We always make our determinations before the addition of the acetanilid. 



Comment by authors. Manufacturers are aware that the Pharma- 

 copoeia prescribes a maximum for solids, and therefore if a pre- 

 servative is added il should be only in such amounts as to keep well 

 within the limits. 



DISCUSSION OF RESULTS. 

 HYDROGEN DIOXID. 



As before stated, the value of a solution of hydrogen peroxid is 

 largely judged from the percentage of hydrogen dioxid present. 

 The investigations were begun in October, 1907, and continued 

 over approximately one year. The results obtained on hydrogen 

 dioxid by the gasometric methods and the iodin method do not 

 materially vary from those by the pharmacoposial method, and for 

 that reason the latter will be made the basis of comment. The 

 Pharmacopoeia states that hydrogen peroxid solution should contain, 

 when fresh, about 3 per cent by weight of absolute hydrogen dioxid, 

 corresponding to about 10 volumes of available oxygen. 



A review of the results obtained by the first examination shows 

 that 21 of the samples fall below the 3 per cent basis and 8 fall below 

 a 2.75 per cent basis. The results obtained five and six months 

 after the first examination show that 24 of the samples examined 

 had lost 10 per cent and over of the original content of hydrogen 

 dioxid, while on a 15 per cent basis, 21 were found defective, which 

 is only 3 less than on the 10 per cent basis. The point may be 

 raised that this commodity is less stable in warm than in cold weather, 

 but this generally accepted idea is not supported by the data. The 

 degree of deterioration taking place between 5 and 6 months and 

 9 and 10 months, respectively, which covers the summer period, 

 does not differ materially from that noted over similar periods of 

 time in cooler weather. It should, moreover, be noted that these 

 observations were made after the samples were at least five or six 

 months old and deterioration had set in, a condition favorable for 

 decomposition. 



Knowledge of trade conditions leads to the belief that it is not 

 necessary to keep hydrogen peroxid solutions on hand longer than 

 five or six months, the latter being the maximum limit. 



ACETANILID. 



The results of this work undoubtedly show that acetanilid retards 

 the deterioration of hydrogen peroxid solutions. The inhibition, 

 however, is not uniform. For example, of two samples of hydrogen 



