VOL. 4, NO. 12
NEW
Amomnc HYDROGEN SULPIDE GENERATOR
1549
tically clear. By this treatment all of the insoluble material carried into section A, the ferrous sulfate, and silt will be removed and a fresh clean surface of ferrous sulfide will be left in the generator. The acid container should also be washed. Allow the water to drain from the generator; close the openings in sections A and D; fill the acid jar with fresh acid. The generator is now in fine operating condition. If a thorough washing of the ferrous sulfide is carried out after each lot of acid is spent, it will not be necessary to open the generator until the whole of the charge, about 200 lb., of ferrous sulfide has been used up, as the ferrous sulfide will move toward the bottom of section B as it is dissolved, and the acid lead from section E to section A will not become clogged by the insoluble material. One generator of the size described in this article will supply hydrogen sulfide in sufficient quantity for 200 students working in qualitative chemistry when closed precipitation flasks are used. These generators may be obtained from the ceramic companies for about $37.00. The cost of hydrogen sulfide when prepared from commercial ferrous sulfide and sulfuric acidwill be approximately 25'#the pound.
s-ary A new automatic hydrogen sulfide generator, simple in construction, inexpensive, and positive in operation has been described. The generator is easily filled and cleaned, and does not clog in operation. The generator is not easily broken, and may be constructed in any size to suit the laboratory requirements. The generator may be easily secured on specifications from the ceramic companies.
Airship Gas Source Seen in Atmosphere. Airship makers take courage. Helium, the valuable safety gas so much in demand for filling balloons, may be obtainable in unlimited quantities from ordinary air. This optimistic suggestion comes from Dr. Frederick G. CottreIl of the Fixed Nitrogen Laboratory, one of the country's foremost experts in the chemistry of the atmosphere. Unfortunately, there is but one part of helium in 180,000 of common air. On the other hand there is a lot of air. Dr. Cottrell's hopes are based on the prospect of separation of air into its component gases in a large industrial way, whereby the oxygen, in particular, is to be more efficiently used in combustion. When this sort of wholesale air analysis is undertaken, the helium content of the atmosphere will unquestionably get attention. It is estimated that some fifty million cubic feet of helium per year go through the blast furnaces of America, along with the enormous volume of air feeding the f5res. If it could be salvaged, this quantity of helium alone would revolutionize the airship industry-Sn'eme Service
