218 THE USE OF IODINE IN BLOWPIPING. 
Wheeler and Luedeking, of Washington university, St. 
Louis, Mo., and published in the Zransactions of the 
Academy of Science, of that city (Vol. IV, No. 4). While 
working on Dr. Haanel’s method they found that the 
alcoholic tincture of iodine served as well in the case of 
all sulphides as hydriodic acid, and that the dry scales 
of iodine worked equally well with the sulphides. The 
next step was easy and natural, perhaps suggested by 
Von Kobell’s experiment with potassium iodide and 
sulphur. It was to mix iodine and sulphur so as to con- 
vert all compounds to sulphides. This they accom- 
plished by adding iodine to melted sulphur and pouring 
the liquid mass on cool glass. The resulting mass is © 
dark iron gray with a tinge of brown, and consists of 
sulphur iodide, S, I,, in an excess of sulphur. The pro- 
portions recommended by them are forty parts of iodine 
to sixty of sulphur. The cooled mass is broken up, 
powdered and kept in a stoppered bottle; when used it 
is mixed, slightly in excess, with the powdered sample 
and the mass is treated with the oxidizing flame. The 
superiority of the solid reagent offered by Messrs. 
Wheeler and Luedeking over the unstable hydriodic 
acid of Haanel must beat once apparent. It is more 
portable and is always ready for immediate use—a 
feature of no slight advantage in general practice. 
It is impossible to give any adequate description of 
the results without the samples, though Haanel’s paper 
as well as Wheeler and Luedeking’s are beautifully 
illustrated in chromo lithography. 
The adjectives used in the description of the films, 
taken from Haanel, are determined from the spectrum 
of the film in question. This can readily be done as 
follows: Support a small piece from the end of a plas- 
ter tablef in plane with a clean piece of glass, scrap- 
ing the plaster down to thesame thickness as the glass. 
Place the assay on the plaster and gently direct the 
102 
