2 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The oxides and acids formed by combustion were first distilled and 

 collected in bromiue water as an oxidizing agent by Sauer * and this 

 method was still further improved by Mixter, f who avoided the use of 

 a rubber cork in the forward end of the combustion tube, carried for- 

 ward the volatilized substance by a current of carbonic dioxide, and 

 suggested more efficient means for oxidation by bromiue and absorp- 

 tion. All these methods depend upon the formation of sulphuric acid 

 and precipitation as baric sulphate, which involves considerable labor 

 when a large number of determinations are necessary in a limited 

 time. To overcome this difficulty Burton j suggested a modification of 

 the method of Sauer, which consists in absorbing the oxidized sulphur 

 in a standard solution of potassic hydrate and titrating the excess of 

 alkali with standard sulphuric acid. 



Besides these methods the only other suitable means for the deter- 

 mination of sulphur in oils with large percentages of sulphur is the well 

 known method of Carius, in which the substance is oxidized in a closed 

 tube by means of fuming nitric acid. In its applicability to all classes 

 of compounds, and in the accuracy of results of which it is capable, this 

 method leaves little to be desired except perhaps in the analysis of 

 oils containing less than one hundredth of one per cent of sulphur. On 

 account of the limited weight of substance that can be oxidized in a 

 Carius tube another method must be selected for substances containing 

 less sulphur. Our experience has shown that the Carius method may 

 be relied upon in sulphur determinations to yield concordant results 

 within a few hundredths of one per cent. Oxidation of the less vola- 

 tile oils containing a small percentage of sulphur, without doubt, may 

 be accurately accomplished in an open vessel, but with larger amounts 

 of sulphur the action of nitric acid is so violent that it must entail 

 loss by volatilization, unless indeed the sulphur oil is considerably 

 diluted by a sulphur-free oil, in which case the solvent must be com- 

 pletely oxidized. 



The great number of sulphur determinations in crude oils and 

 products obtained from them, connected with the extended examina- 

 tions which have occupied my attention during several years past, has 

 demanded a careful comparison of the various methods as to their 

 efficiency and economy of time. Particular attention has been given 

 to details of the Carius method, with the precautions necessary in its 

 successful application to the analysis of sulphur oils. The first requi- 



* Fres. Zeit. Anal. Chem., XII. 32. 



t Amer. Cliem. Journ., II. 396. J Ibid., XI. 72. 



