1644
JOURNAL OF CHEMICAL EDUCATION
JULY.
1930
5. Is. hydrogen sulfide lighter or heavier than air? (Heavier) 6. Does hydrogen sulfide have any odor? (Yes) 7. Is hydrogen sulfide acidic or basic in properties? (Acidic) 8. I n general, t o what group of compounds would you add any reasonably strong acid t o producehydrogen sulfide? (Sulfides) 9. Whenever silverware turns black i t constitutes s test for what element? (Sulfur) Or, a fruit jar rubber was found in contact with a silver kniie on which was a circular black ring. This shows the presence of what element in the ring? (Sulfur) 10. A paper moistened with a solution of a soluble lead salt on expasure to an unknown gas turned Mack. What was the gas? (Has) 11. I n the burning of hydroken sulfide what product may be obtained which is a gas a t room temperature? (Sulfur dioxide) 12. I n burning hydrogen sulfide, what product may be obtained which is a solid a t room temperature? (Sulfur) 13. I n burning hydrogen sulfide what product is formed which is a liquid a t room temperature? (Water) 14. When hydrogen sulfide is bubbled into a blue vitriol solution, give the formula of the precipitate. (CuS) 15. What color is the precipitate in No. 14? (Black) 16. What color is zinc sulfide? (White) 17. What colm is cadmium sulfide? (Yellow) 18. Is a water solution of hydrogen sulfide highly or slightly ionized? (Slightly) 19. Is hydrogen sulfide a good reducing or oxidizing agent? (Reducing) 20. What is the valence of S i n the sulfides? (Negative two)
The above procedure has been tried for approximately a year now on two different classes of genera1,chemistry students of about thirtyfive or forty in each class; the laboratory group, itself, consisting of approximately twenty students. It is $arly to predict all the results, either good or bad, as compared with the former method. It is very refreshing, however, to note how spontaneously the students come to their instructors with their questions. Where formerly only that small group of questioners would venture unless strongly urged to do so, now nearly all seem to feel some impetus to come. The students, themselves, state freely that they are learning more during their laboratory period than formerly. The fact that both groups were started for a few weeks following the usual plan, gave them some basis for comparison. It is our opinion, also, that the grades from the examinations on the textbook work as a whole are being decidedly benefited by such a method. While it means somewhat more work a t the time for the instructor, yet this is offset by the fact that the tedious reading of a formal notebook on week-ends is decreased to a delightful minimum.
Mercury Production in the Bogojno district of Jugoslavia has been begun by a Polish group. Up to now, two chamber ovens have been put into operation, eight tons of ore being worked up daily. I t is hoped to bring others into operation in the near future.-Cham. Age
