abstracts: chemistry, analytical chemistry 489 



CHEMISTRY. — Application of the dimethyl sulfate test for determining 

 small amounts of petroleum or asphalt products in tars. Charles 

 S. Reeve and Richard H. Lewis, Office of Public Roads. Eighth 

 International Congress of Applied Chemistry, 1912. 

 This paper, after briefly reviewing the literature on the dimethyl 

 sulfate test, notes that the best method to date fails to detect the pres- 

 ence of open-chain hydrocarbons in tar-asphalt mixtures when the 

 asphalt or petroleum is 10 per cent or less of the mixture. Commer- 

 cial specifications are now being drawn which require less than 10 

 per cent of asphalt in mixtures with tar. The authors proceed to 

 show that as low as 3 per cent of asphalt or petroleum can be detected 

 in these mixtures by making the dimethyl sulfate test on higher boiling 

 fractions (315°C.-350°C. and 350°C.-370°C.). Tables of experimental 

 data are given. 



The results do not give any absolute idea of either the amount or 

 exact nature of the material which has been fluxed with the tar. It 

 is thought possible, however, that the improvement which has been 

 made in the test will enable the chemist to ascertain whether his speci- 

 fications are being fulfilled, by checking up the material supplied against 

 laboratory mixtures of the same amount and grades of materials re- 

 quired. C. S. R. 



ANALYTICAL CHEMISTRY.— Determination of manganese as sul- 

 fate and by the sodium bismuthate method. William Blum. Bul- 

 letin of the Bureau of Standards 8: Reprint 186. 



Manganous sulfate is the only compound adapted to accurate weigh- 

 ing of manganese, either in gravimetric analysis, or in obtaining a 

 definite amount of manganese as a primary standard. Of the various 

 volumetric methods considered, the bismuthate method appeared to 

 be most nearly free from the influence of the precise conditions of opera- 

 tion, and therefore most suitable for use as a standard method. 



This method depends upon the oxidation of manganese to perman- 

 ganic acid by sodium bismuthate in nitric acid solution. After filtration 

 thru asbestos to remove the excess of bismuthate, ferrous sulfate is 

 added in slight excess, which is then titrated with permanganate of 

 known manganese value and of known ratio to the ferrous sulfate. The 

 method of standardizing the permanganate is of course fundamental, 

 and forms the principal subject of this paper. The manganese value 

 may be determined by two general methods: (a) titration of a known 

 amount of manganese, e.g., as MnS0 4 , under the conditions of opera- 



