EXAMINATION OF HYDROGEN DIOXID SOLUTIONS. 17 



MERCK & Co. 



* * * We have looked over your tabulated results with interest. From the 

 tabulation which you offered it appears that in the acidity test the method of the 

 United States Pharmacopoeia has been employed. But do you not think this method 

 rather unreliable? This question was raised about three years ago by numerous 

 investigators. 



Replying to your favor of the 13th, asking us to advise you as to what we consider 

 a reliable test for determining the amount of free acid in pharmacopoeial hydrogen 

 peroxid, we would say that we obtain the most accurate results by the use of methyl 

 orange indicator instead of the phenolphthalein indicator prescribed by the United 

 States Pharmacopoeia. 



Uniform and accurate results may also be obtained by simply titrating the original 

 solution of dioxid with decinormal potassium hydroxid, using methyl orange and 

 omitting all evaporation and heat. 



Comment by authors. The observations noted are in accordance 

 with our findings. 



OAKLAND CHEMICAL Co. 



Replying to your letter of December 16, received yesterday, we beg to thank you for 

 it. The plan that you are using of notifying manufacturers of the results of your 

 investigations and the opportunity you are offering for comment on the report is very 

 fair and commendable. 



May we ask you to kindly give us the numbers which are stamped with a rubber 

 stamp on the labels of the bottles which you have been using as samples? We ask 

 this information so that we can check up your results with our records. We take it 

 that this will not be unsatisfactory to you, and it will certainly be a matter of satis- 

 faction to us to make the comparison. * * * 



We beg to acknowledge receipt of your favor of the 5th instant. None of our records 

 show anything that would compare with your report on this sample. The uniformity 

 of the other four and the relative closeness of your statement with our results justify 

 the assumption that the report on sample No. 5 can not be accepted as indicating 

 either an exceptional case or a fair average of quality of our product; the not unrea- 

 sonable possibility of something unusual having happened to this sample either 

 before or after it reached your hands, the further possibility that it may not actually 

 be our product, though apparently an original bottle bearing our label, are sufficiently 

 important to warrant our request that this sample be either eliminated or a full oppor- 

 tunity be given us to make a rigid investigation that would allow us to trace its history 

 completely. * * * 



Your favor of March 1 was duly received. The statement that the label on the 

 package of dioxogen, on which there is some question, contains the number 91, and 

 which statement had previously been made in a department letter of January 13, has 

 been carefully reviewed, and we beg to make you the following report. 



The number referred to, which is placed on these bottles, is the key by which we 

 can identify each lot of our product, its date of manufacture, and all the records which 

 refer to it. These numbers run in series. The present series of numbers began in 

 March, 1907, and No. 91 of this series was reached December 15, 1908. If the bottle 

 bearing the mark received by your department from Co. was obtained in 

 October, 1907, it could not have belonged to this series started in March, 1907, and 

 must have belonged to a previous series. 



The previous series began in November, 1904, and No. 91 of this series was reached 

 August 13, 1906. In August, 1906, Co. received a shipment of goods bearing 

 this number. Consequently this bottle, which your department has reported on, had 

 21450 Bull. 15012 3 



