in the pig iron passing into the vessel is more than sufficient to effect a thorough desulphurization.  Indeed, 1 to 1.2 per cent. of manganese is sufficient to effect a satisfactory desulphurization.  For the extent of the removal of the sulphur, the temperature and the duration of the reaction are of importance.  It has been found that if highly sulphureted pig iron is poured from the blast furnace into the desulphurizing vessel, fifteen to twenty minutes are sufficient to effect the desulphurization requisite for the steel process.  The part played by the duration of the process is seen from the results obtained with the last charges, if the vessel is emptied at the end of the week without fresh pig iron being added from the blast furnace.  If, for example, 60 tons of pig iron with 0.065 per cent. of sulphur remain in the vessel, the proportion of sulphur with the last charges falls to 0.03 per cent.  The iron in the vessel remains sufficiently fluid for several hours.  When necessary, a little wood is thrown in.  It has been found quite unnecessary to obtain heat by passing and burning a current of gas above the bath of metal.

A number of results, showing the separation of sulphur at the Hoerde Works, was published a few months ago[2] by Professor P. Tunner, one of our honorary members.

  [Footnote 2:  “Oesterreichische Zeitschrift fur Berg und
  Huttenwesen,” 1891, No. 19.]

The totals represent, respectively, 138,500 kilogrammes of pig iron and 98,654 kilogrammes of sulphur.

Thus, from 138,500 kilogrammes of pig iron there has been eliminated 179,577-98,654 = 80,923 kilogrammes of sulphur, or, in other words, 45.063 per cent.

The proportion of sulphur in the slags rises with that in the iron from the blast furnace to 17 per cent., an inappreciable portion of the sulphur of the slag being oxidized to sulphurous anhydride by access of air.  An analysis of the slag yielded the following results: 

Per cent. 
Sulphur                        17.07
Manganese                      30.31
Phosphoric anhydride            0.61
Iron                            7.13
Bases                          35.04

An analysis of an average sample gave: 

Per cent. 
Manganese sulphide             28.01
Manganous oxide                20.23
Ferrous oxide                  25.46
Silica                         18.90
Alumina                         5.00
Lime                            3.53
Magnesia                        0.43

The great convenience and certainty presented by the method described in this paper will in all probability lead to its general adoption.  As a matter of fact, several works are now occupied with the installation of this mixing and desulphurizing plant.

* * * * *

ON THE OCCURRENCE OF TIN IN CANNED FOOD.

By H.A.  WEBER, Ph.D.