

240 



422 OBSERVATIONS IN CHEMISTRY AND MINERALOGY. 



replaced in air-bath and kept at temperatures ranging between 180°-194° C 

 for 6% hours; a small quantity of floury sulfur is now seen floating on liquid 

 roscoelite is barely attacked. Following morning began heating air-bath at 

 8 h. 50 m. Temperature brought up rapidly and kept at between 235° C. to _ 

 until 3 h. 20 m.; that is 63^ hours. Color of liquid is strongly greenish-blue 

 the dark roscoelite particles have disappeared, the quartz sand is nearly white! 

 Sulfur is in many drops (liquid) ; there are no yellow specks. Attempt to unite 

 many sulfur drops by replacing tube into oven, without success. After cooling, 

 opened the tube and filtered the content. 1 c.c. of filtrate requires 3.0 c.c. of 

 permanganate; 17.1 c.c. — 14.1 c.c. have been used up in action or 82.5 per 

 cent of the S0 2 has been changed into sulfur and sulfuric acid. The entire 

 filtrate was then kept boiling until S0 2 was expelled and then the sulfates were 

 precipitated by BaCl 2 , resulting in 7.8842BaS0 4 . To this must be added 0.303 

 BaS0 4 , which was recovered from the residue, having been stored therein as 

 CaS0 4 (originally dolomite). From the residue was recovered 0.5510 gram of 

 elementary sulfur by volatilizing all the quartz with hydrofluoric acid. 8.1872 

 BaS0 4 give 1.1255 grams of sulfur, hence follows elementary sulfur: sulfuric 

 sulfur - 0.551 : 1.1255 = 1 : 2.04. This tallies exactly with the formula 



3S0 2 = S + 2S0 3 . 



The question now arises : does the vanadyl play any special r61e in the action 

 of the sulfurdioxyd, or does the same action take place for any decomposable 

 silicate, no matter what the bases may be? The following two experiments give 



an affirmative answer to the second query. 



III. One gram of black slag finely ground was sealed up with 50 c.c. of sul- 

 furous solution. Slag came from cupola-furnace of copper-smelter and is high 

 in iron. Slag decomposes rapidly at 235° C, throwing out silica of very volumi- 

 nous character. Sulfur is so intimately involved in this silica that it does not 

 show. After filtering, drying the residue, eliminating the silica by hydrofluoric 

 acid, and finally dissolving the sulfur in redistilled carbon disulfid; on evaporation 

 of the latter 0.202 gram pure sulfur was recovered. 



IV. Orthoclase represents that type of polysilicate which is not decomposable 

 readily by sulfuric acid. 1.0 gram of finely ground orthoclase was sealed up m 

 tube with 40 c.c. of the sulfurous solution. Tube was kept 18 hours at tempera- 

 ture ranging between 230° and 250° C. Again the residue showed ^reiy t 

 sulfur to naked eye; under microscope it is easily seen. The filt / a ^ ubic 



or 



pelling sulfurdioxyd— which had come down to 2.2 c.c. permanganate per 



centimeter, 1.5117 of BaS0 4 was obtained. This gives 0.519 gram oid 

 0.208 of sulfur as the product of the action in forming aluminum suna 

 potassium sulfate from the orthoclase. oMion 



Conclusion.— ■" It is experimentally proven that sulfurdioxyd in aquew 



and in presence of a silicate which is decomposable by sulfuric aci 



