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valve M. Next, t h e instrument is raised t o the place where t h e sample is t o be collected and t h e water allowed t o seek t h e former levels a t D and E . The water in falling t o E sucks in a sample of t h e air t o he tested. Next t h e valve M is closed a n d t h e platinum wire N electrically heated. The methane in t h e combustion chamber burns t o carbon dioxide a n d water, thus: CH, i2 0 2 = COS 2H20 i. e., contraction in volume of t h e sample occurs corresponding t o t h e amount of methane originally present in t h e sample. At the end of I'/~ min. t h e electric current is turned off a n d t h e instrument shaken t o cool t h e gases in t h e combustion space a n d bring t h e m t o t h e same temperature a s t h e gases were a t t h e beginning of t h e test. The water in t h e combustion space will then rise t o take t h e place of t h e burned-out gas and fall a corresponding distance in the glass tube B , i. e . , fa!l t o a point on t h e graduated scale t h a t will show t h e per cent of methane originally in t h e sample. A previous calibration, once and for all time, fixes t h e proper graduations on this scale. The latter carries four graduation columns, one for methane and natural gas, one for hydrogen, one for gasoline vapor, and one for coal gas. The electrical energy for heating t h e platinum wire is derived from a miner's electric cap lamp storage battery, thereby providing t h e electric cap lamp with a gas detector, something i t doe's not possess a t present and which has been a n objection t o the use of electric lamps in gaseous mines. A t Fig. 111 is shown another gas detector similar in operation except i t contains two small dry cells, A and B , for supplying t h e electrical energy. These cells cost about 7 cents apiece and will operate t h e detector for a minimum of 20 determinations. When they are used up, they are as easily replaced (by unscrewing t h e cap D ) as t h e d r y cells of t h e well-known Ever-Ready flashlight batteries. The author is indebted t o several members of the Bureau of Mines for assistance in developing this instrument. Dr. G. A: Hulett, Consulting Chemist, first suggested t h a t a n apparatus of this nature be constructed, a n d 0. P . Hood, Chief Mechanical Engineer, rendered valuable assistance in designing it. Patent claims have been filed by t h e Bureau of Mines on t h e above instruments a n d means for exploiting i t are being considered so t h e best interests of t h e public will be served.
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PITTSBUROH
AN APPARATUS FOR DIGESTING CRUDE FIBER By J. M. P~CBBL Received May 28, 1915
I n a n article'.by t h e author several years ago, i t was stated t h a t round-bottom flasks, through which cold water is passing, set on t h e beakers in which crude fiber is digesting, prevent evaporation and hold frothing in check. The apparatus pictured here is t h e outgrowth of t h a t idea. The distinctive feature of it is the round-bottom reflux condenser. I
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T H E CONDENSERS-In Fig. 1 eight of t h e condensers are shown resting on t h e beakers. Two are shown suspended above t h e beakers. One is suspended. giving a view of t h e tube, through which t h e cooling water passes out of t h e condenser. Another, lying on t h e heating plate, affords a top view. The parts of a condenser (see Fig. 11) are: ( a ) a zinc or copper-in this case i t chances t o be zinc-shell (hemisphere) 7 . 6 cm. in diameter; ( b ) a copper ring, similar t o those used on water baths, about I O cm. in diameter, t h e circular opening in t h e ring being about 5 . 7 cm. in diameter, this ring is soldered t o t h e shell; (c) a copper cone whose big end is about j . 7 cm. in diameter, small end about I cm. in diameter ( I . 5 cm. would be better) and vertical height ahout 4 . 5 cm., this cone is soldered t o t h e ring; ( d ) a copper tube about I cm. in diameter ( I . 5 cm. would be better). and about 11 cm. long, soldered t o t h e cone; in the side of this tube near its top is a small hole, by means of which t h e condenser may be suspended on a catch or hook on t h e influx t u b e ; ( e ) a n elbow-shaped exit, or overflow, tube, ahout 4 mm. in inside diameter (I cm. would he better), length (horizontal) t o the elbow
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about 7 . j cm., length (vertical) about 10 cm.; this tube is soldered t o the tube ( d ) about 3 . 5 cm. above t h e cone.' THE D E L I V E R Y TUBES-The cooling water is delivered into t h e condensers from the water-main b y branch tubes each provided with a stop-cock. These cocks are ordinary brass gas-cocks, in t h e nozzles of which are soldered copper tubes ahout 4 mm. inside diameter and 2 4 cm. long. The adjustment should be such t h a t t h e lower ends of these tubes are about 4 mm. above t h e bottoms of t h e condensers when t h e y are suspended and about I t o 2 cm. below t h e t o p of the cone when t h e condensers rest on t h e beakers. The condensers are suspended from a little catch or hooks soldered t o t h e delivery tubes. Whether the condensers he suspended above the beakers or he resting on them, the water circulates through them freely and spills into a trough back of t h e heakersno rubber connections. A horizontal strip with holes in it, through which the overflow tubes pass, keeps the exit ends of these tubes centered over t h e trough. I t is important t h a t these ends should always he visiI Since writins the above. an ordinary glass flask. whore neck i s provided with a suitable side-tube. has been used quite satisfactorily for several months instead of one of the metallic condensers.
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ble so t h a t one may a t a n y time know t h a t there is ample flow of water through t h e condensers. These tubes should not, therefore, dip into t h e trough. The trough (galvanized sheet iron) is about 3 . 5 cm. wide, about 13 cm. deep and. of wafer course, extends along t h e entire length of t h e “plant.” These condensers prevent completely loss of liquid by evaporation, and suppress, or hold sufficiently in check, frothing. But t h e boiling must be started gently and conducted gently; violent ebullition is not at all necessary and is t o be avoided. Frothing is due t o bubbles filled with steam-and doubtless t o some extent with hot air; condense t h e steam and t h e bubbles or froth collapse. The upper region of t h e beakers is kept cool by t h e condensers; hence FIG. 11-REFLUX CONDENSER there is no need of a cold FOR USE ON BEAKERS IN CRUDEFIBERDESERblast of air-it is t h e coldMINASION ”ress, not t h e blast, t h a t checks ( 1 1 4 Size) t h e frothing. A cold airblast could, however, be easily introduced through these condensers. Such a condenser is shown on a beaker in t h e foreground of Fig. I. Beakers of joo cc. capacity, 7 . j cm. inside diameter and 14 cm. high, Jena glass, are preferred; b u t beakers of 600 cc. capacity, 8 cm. diameter, I j . 5 cm. high, can be used interchangeably with t h e smaller ones. The beakers can be given a rotary shaking without lifting t h e m from t h e heating plate. After t h e boiling has been gotten under way and t h e beakers have been rotated a time or two, t h e apparatus may be left to itself. The heating plate (wrought iron) is about 4 mm. thick and has a top surface about 9 . j cm. wide. Along its entire length is turned a flange about 2. j cm. wide. The object of t h e flange is t o give rigidity and prevent sagging or buckling. LABORASORY OF THE NORSHCAROLINA DEPARTMENT OF AGRICULSURE, RALEIGH
A FURNACE FOR CRUDE FIBER INCINERATION By J. M. PICKEL Received May 28, 1915
If t h e chemist have a t his dispbsal t h e requisite electric current and $ 5 0 t o $100, he will be a p t t o invest in a n electric furnace. If he have b u t a dollar or two, he can, with t h a t capital and with materials ready t o hand in t h e laboratory, construct a wonderfully efficient incinerating furnace. Such a furnace, occupying on t h e table a space 2 0 X 2 0 cm. (8 X 8 in.), is shown in Fig. I in t h e previous article (page 3 6 6 ) , at t h e left uncovered, a t t h e right as it appears when performing. Twelve crude fiber incinerations are made in I j t o 2 0 min. on, or in, this furnace
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by t h e heat of one small Bunsen burner; and t h e ash is as nearly perfect as t h e writer a n d designer of t h e furnace has ever seen. A piece of asbestos board 0 . 7 X 1 9 X 19 cm., in whose center is cut a circular opening Q cm. in diameter, is laid on an ordinary laboratory tripod. On this board is set a disc of wrought iron (cast iron would probably be better) about 2 . 5 mm. thick a n d 1 3 . 5 cm. in diameter (14. j cm. would be better since i t would furnish space for several more incinerations). The disc is supported on three legs, I cm. long, screwed into it. On t h e disc are set 1 2 crucibles. alundum RA 98, 3 . 8 cm. high and 3 . 7 cm. in outside diameter, in which t h e fiber has been filtered, washed, dried and weighed. On t h e asbestos board is placed a n asbestos cylinder 15. j cm. in diameter a n d 6 . 5 cm. deep. The cylinder is covered with a piece of asbestos board of t h e same dimensions as t h e one previously described, but having in its center a hole only 3 . j cm. in diameter. A small Bunsen burner, whose gas tip has been widened somewhat by inserting t h e point of a penknife blade, furnishes t h e heat. The burner should be set o n a block so as t o bring its t o p close t o t h e iron disc, thus causing t h e flame t o spread over t h e under surface of the disc. I n a few minutes (6 or 8) t h e disc and t h e crucibles will be brought t o a bright glow. The cylinder is easily and quickly made. Strips of suitable width (about 6. j cm.) are cut from asbestos board of suitable thickness (about 7 mm.) and their ends beveled by shaving with a sharp knife. These strips are saturated with water, and, while wet, are wound, two or three thicknesses, around a suitable core (an empty 2-kilo ether can dr a piece of sheetiron stovepipe), bound in place by two or three bands of wire and allowed t o dry out a t room temperature and finally on or near a steam radiator. The core is removed and t h e lapped ends of t h e strips riveted. LABORATORY OF SHE NORTHCAROLINA DEPARSMENT OF AGRICULTURE, RALEIGH
A GAS PRESSURE REGULATOR By J. R. POWELL Received November 15, 1915
Occasion arose in this laboratory t o make use of a gas-heated thermostat, but a great deal of inconvenience was experienced because of varying gas pressure. I n casting about for some simple pressure regulator, the apparatus described below a n d illustrated in Fig. I was finally hit upon as a practical solution of the trouble. I t will be noted t h a t t h e apparatus is constructed from material readily obtainable in almost any laboratory; also t h a t there is no great skill required for its assembly. Practically every chemist has t h e rudimentary knowledge of glass-blowing necessary t o make t h e one “ Y ” required. A and C are rigidly fastened, in t h e position shown, t o a board which acts as a mounting for t h e whole apparatus. B is suspended inside of A on t h e end of E by a rubber stopper. E is so arranged t h a t it may
