THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



MARCH 1856. 



XXI. Remarks on the Estimation of Sulphur in Iron, and on the 

 Solubility of Sulphate of Baryta in Nitric Acid. By E. Cham- 

 bers Nicholson and David S. Price, Ph.D.* 



THE method usually employed for estimating the amount of 

 sulphur in a metallic substance, is to act upon it either 

 with nitric acid or aqua regia, and then to precipitate the sul- 

 phuric acid with a solution of a salt of baryta. By pursuing 

 this plan for the determination of sulphur in cast iron, the solu- 

 tion obtained by oxidizing 10 grammes of the metal with nitric 

 acid was evaporated to dryness for the purpose of rendering the 

 silicic acid insoluble, the residue then digested with dilute hydro- 

 chloric acid until free from iron, and the sulphuric acid in the 

 solution thus obtained precipitated with chloride of barium. The 

 quantity of sulphur found by this method will be seen by the 

 Table, column 1, far to exceed that afterwards arrived at by 

 adopting another process. This process consisted in dissolving 

 the same weight of iron in hydrochloric acid, and passing the 

 gases evolved through a solution of acetate of lead slightly aci- 

 dified with acetic acid. The precipitate of sulphide of lead thus 

 produced was collected. on a filter, washed, dried, and the per- 

 centage of sulphur calculated from the weight obtained (see 

 column 2). The residue from the iron, consisting of graphite 

 and silicic acid, was collected on a filter, dried, and then fused 

 with a mixture of nitre and carbonate of soda, in order to ascer- 

 tain if all the sulphur had been eliminated as hydrosulphuric 

 acid. The fused mass was dissolved in water, the solution aci- 

 dified with hydrochloric acid, and then evaporated to dryness to 

 separate silicic acid. To the solution obtained by digesting this 

 * Communicated by the Authors. 

 Phil. Mag. S. 4. Vol. 11. No. 71. Mar. 1856. N 



