INDUSTRIAL AND ENGINEERING CHEMISTRY
July, 1928
inches long and a 1-inch inner tube. Contact is made with the granular carbon packing on each end by graphite collars that may be tightened by thumb screws. Otherwise the construction is very similar to that of the pot furnaces. Sei-era1of these furnaces have been constructed in this laboratory and have given satisfactory service under widely
771
varying uses. Temperatures of 1200" C. have been maintained for hours. The granular carbon must be replaced occasionally, but that is very easily done by pulling out the inner tube, taking out the old carbon, screening out the fines and repacking. These furnaces are splendidly adapted for alloy research.
An Improved Gas Generator' V. T. Jackson UKIVEKSITY O F FLORIDA, GAIKESVILLE, FLA.
H E gas generator for hydrogen sulfide, described herein, has been used in the qualitative analysis laboratory of the University of Florida for several months. It has required a minimum of care and proved very satisfactory. The stand for the generator is shown in Sketch I. The bottom, shelf, and sides are made of 10-inch (25.4-cm.) boards. The bottom is 24 inches (61 cm.) long. The sides are 31 inches (78.7 cm.) high. The s i d e s a r e f a s t e n e d 2 inches ( 5 cm.) from the ends of the bottom. Holes are bored through the ends of the bottom for screws to fasten the stand to t h e t a b l e t o p . The s h e l f , A , is p l a c e d 7 inches (18 cm.) from the tops of the sides. A 3-inch (7.6-cm.) hole, with beveled edge, is bored 4.5 inches (11.4 cm.) from the r i g h t hand end of the shelf. -4 1-inch (2.5-cm.) hole is bored to the left and in front of this hole. The Sketch I strips B and C and the cross strip BC are made of 1-inch (2.5-cm.) square lumber. The complete generator is shown in Sketch 11. D and E are 8-liter aspirator bottles, with an opening near the bottom of each. F is a 2-liter acid bottle. L is a \Tide-mouth bottle; it should have a capacity of at least a liter, preferably larger. The bottle F is fitted with a 2-hole rubber stopper. A length of 3 mm., inside diameter, glass tubing, G, is passed through one of these holes so that its outer end extends just beyond the stopper; the other end should reach nearly to the bottom of the inverted bottle. The glass tube J , 8 to 10 mm. inside diameter, should juqt pass through the other hole in the stopper in F , and should reach to the T-tube I , to which it is joined by a rubber connection. The tube N is joined to the other end of the T-tube by a rubber connection and is extended to the bottom of E. The glass tube K , inside of the bottle E, of 20 mm. inside diameter, should extend from the bottom of the bottle to within 10 to 15 em. of the neck of the bottle. Glass and rubber tubing of the same size as the tube J should connect the lower opening of the bottle D with the free arm of I . A Hoffman screw clamp is placed over the rubber tubing at H . The glass tube M should be of the same size as J . It should barely pass through the rubber stopper in the mouth of E , and should go to the bottom of L. Four holes should be bored in the rubber stopper for the
T
1
Received February 13, 1928.
bottle L, for stopcocks, which are bent and inserted as indicated. Pieces of rubber tubing, of such length that they will not quite touch the bottom of the stand, are fastened to the free ends of the stopcocks. A glass tube is attached to one of these when one wishes to use the gas. A 1-hole rubber stopper, through which is passed a 6-em. length of glass tubing of the same size as J , is inserted in the hole (not shown in sketch) near the bottom of E. A 60-cm. length of rubber tubing is attached to the free end of the glass tube, which is closed with a Hoffman screw clamp. The bottle E is filled to a depth of about 8 cm. with broken glass. The tube K is then placed in position as indicated. The bottle is then filled to the height of K with ferrous sulfide, and over the top of this is placed a layer of glass wool. The bottle is then closed with the rubber stomer, - _ bearing- the two indicated t u b e s . The bottle L is filled two-thirds with g l a s s wool, r a t h e r t i g h t 1y p a c k e d , and the remaining space with cotton, loosely p a c k e d . This prevents s p r a y from being carried over into the precipitating vessel. The bottle D is filled with dilute hydrochloric a c i d . T h e screw clamp a t H is t h e n o p e n e d and the bottle F is filled about one-third with the acid. One of the stopcocks is then opened a n d t h e acid is allowed t o flow into E . When the Sketch I1 stopcock is closed, the acid FTill generate enough gas, by its action on the ferrous sulfide, to push the acid into F . lT7henthe acid is spent, it may be readily drawn off through the rubber tubing attached to the bottom of E. One filling with ferrous sulfide will last for a t least a year. There is no waste in drawing off the spent acid. It is desirable to precipitate with hydrogen sulfide under pressure. This is done by fitting a conical flask with a 1-hole rubber stopper and passing a 5-cm. length of glass tubing barely through the stopper. The free end of the glass tube is attached to the rubber tubing, fastened to one of the stopcocks. The flask should be opened for a few seconds, to allow the escape of air, after the gas has been turned on. By substituting marble chips or zinc for the ferrous sulfide, a very satisfactory generator for carbon dioxide or hydrogen is made. I
