150 THE ALUMNI JOURNAL 



slowly with a wooden paddle or mechanical agitator for a period of 

 from four to five hours, care being taken to regulate the temperature 

 by the addition of lumps of ice from time to time. The balance of 

 the barium is added in small quantities every half hour until all has 

 been introduced. The reaction is carefully watched during the latter 

 part of the stirring by introducing a piece of litmus paper into the 

 solution. When the solution has reached a neutral point, or has become 

 very slightly alkaline, agitation is stopped, the lumps of ice removed 

 and the precipitate allowed to settle. This requires about fifteen 

 minutes. The clear suppernatent liquid is then removed by decantation 

 and a quantity of wash water from a previous batch is added to the 

 sediment left in the tub. This wash water is really dilute hydrogen 

 peroxide and contains a certain amount of free acid. The contents 

 of the tub are again stirred briskly for a period varying from one 

 hour to one and one-half hours. Ice is added as in the previous treat- 

 ment and when the mixture again becomes slightly alkaline it is per- 

 mitted to settle and the clear solution decanted off as before, the 

 two decantations being mixed together. The solution obtained in this 

 manner will have a strength varying from 3.4 per cent, to 3.8 per cent. 

 This should be carefullv diluted to 3.1 per cent., a sufficient quantity 

 of chemically pure sulphuric acid added to make the product slightly 

 acid and to precipitate the barium in solution as barium sulphate. The 

 acetanilid is also added at this time and allowed to dissolve in the 

 solution. The resultant product may then be filtered or the precipitate 

 allowed to settle and the clear peroxide decanted off. 



To the sediment in the tub is now added about ten gallons of pure 

 water, the mixture stirred for about one hour, allowed to settle and 

 the clear liquid decanted off. The sediment is then treated the second 

 time with about seven gallons of water in the same manner, the clear 

 liquid being poured off at the end and mixed with the first decantation. 

 This forms the wash water for the next batch. 



Peroxide manufacture has long been regarded as a secret by those 

 who have not had the privilege of observing its production. This 

 idea is rather falacious inasmuch as it is really a very simple process, 

 it being only a formula of proper proportions and careful manipula- 

 tion. The above process will answer admirably for those who desire 

 to operate on a small scale, and produce a superior and permanent 

 solution of hydrogen dioxide. The best known manufacturers of 

 to-day, however, are compelled, in order to operate on a profitable 

 basis, to follow the hot process or the sulphuric acid process on a 



