July. 191j
T H E J O l - K S . I L O F ILVDL'STKr.-IL . 1 S D E S G I S E E R I S G C"E.IfIS7'KI.v
held in with K h o t i n s l q cement. T h e t i p can be easily removed for cleaning, or tips of various sizes a d a p t e d t o t h e gas t o be burned can be inserted. T h e air necessary for complete combustion after being purified b y passage through t h e large soda lime tower is supplied t o t h e flame in t w o portions. T h e primary air is drawn in b y t h e gas as i t passes through t h e small t i p : t h e secondary air enters through t h e t w o inlets a t t h e side of t h e combustion chamber. T h e combustion chamber, made of Jena glass t u b ing, is about 360 mm. long and about z j m m . in internal diameter. T h e narrow t u b e a t t h e t o p may be used for introducing water when it is desired t o rinse out t h e apparatus; when in operation this t u b e is closed with a small cork. Satisfactory drainage is provided b y t h e sloping layer of paraffin or sealing wax covering t h e stopper a t t h e bottom. T h e n t h e burner is lighted t h e second a r y inlet air keeps t h e base of t h e a p p a r a t u s cool, b u t t h e rest of t h e combustion chamber u p t o t h e side t u b e is heated so t h a t no condensation takes place on t h e walls. For t h a t reason i t is usually unnecessary t o rinse o u t t h e combustion chamber. By means of a cork connector t h e first of a series of wash bottles is attached t o t h e apparatus. Only one wash bottle is shown in t h e illustration. b u t three are usually required for satisfactory operation. I n order t h a t t h e suction m a y 32% pull the gas steadily through t h e wash bottles it is necessary t h a t t h e end of t h e inlet t u b e of t h e first bottle be perforated with a number of small holes. K i t h a single, large opening t h e operation of t h e burner is not steady. Experience has shown t h a t combustion of t h e sulfur t o oxides is incomplete when t h e flame, because of too little primary air. is smoky or even strongly luminous without smoke, as well as when ,the supply of secondary air is not sufficient. This latter condition is s h o v n b y a flame with an indefinite or "ragged" outline. When t h e gas and air entering t h e burner are so regulated t h a t t h e flame is non-luminous a n d clear-cut, combustion is complete a n d t h e results obtained have been more concordant t h a n those obtained with a n y other apparatus in use in this laboratory. The advantages of t h e apparatus are its small cost, simplicity of construction, and t h e fact t h a t t h e difficulty of lighting and regulating t h e burner usually experienced in t h e use of apparatus of this t y p e is entirely overcome. T h e platinum wires become heated b y t h e gas flame a n d prevent the flame from going out when t h e pressure fluctuates. With a single adjustment it has been found possible t o keep t h e flame
k
621
burning with gases \-arying in composition from pure hydrogen t o pure acetylene and a t pressures ranging from t w o t o t e n inches of water. Of course, comhustion was not complete with such extreme \,ariations. It is, hoyever. easy t o adjust t h e apparatus t o burn completely a n y gas which can be burned in a n y R u n sen-type burner. BLREAUOF STANDARDS ~ V A S H I N G T O N , D.
C.
A MODIFIED PIPETTE By S I D N E Y B O R N Receired February I , 1915
The accompanying sketch shows a form of pipette which has been found very useful in our laboratory. I t is made b y fusing a stopcock and a piece of bent glass tubing t o a pipette. T h e advantages over t h e ordinary pipette are: I . Safety---There is no danger of sucking u p acid or dangerous liquids. 2 . Ease of Manipulation--The stopcock ensures tighter closing a n d greater accuracy t h a n use of a finger. 3. Accuracy--The line of demarcation is level with eye when using. 4 . T h e pipette can be carried around full without losing a n y liquid. I , h B U R A T O R Y O F T H E \\'M.
J. LEMPBREWING CO.
S T . LOUIS
AN APPARATUS FOR THE ,CONTINUOUS EXTRACTION OF A LIQUID BY ANOTHER, AND HEAVIER LIQUID By
ISIDOR
GREENWALD
Reccired hfarch 23. 191.5
T h e need of a convenient a p p a r a t u s €or t h e continuous extraction of a liquid with another, heavier liquid, has been felt for some time. Thc apparatus shown in the accompanying sketch is simplc, compact a n d can readily be made b y a n y glass-bloxer a t little cost. For use? some of t h e extracting liquid is placed in t h e t u b e . I . T h e liquid t o be extracted is then added until t h e extracting liquid is forced u p the t u b e C' almost t o its opening into B . T h e apparatus is t h e n connected, in t h e usual manner, t o a flask containing the extracting fluid a n d t o a condenser. TT'ith t h e apparatus shown. chloroform extracted t h e caffeine from a 2 . .j per cent solution within three hours. For substances extracted Jvith difficulty! the apparatus may be made in a narrower, a n d longer, form. T h e apparatus may he modified b y the use of ground-glass or mercury-sealed connections a n d also by the insertion of n stopcock in either -1 or C for t h e purpose of removinx a sample of t h e extracted, or t h e extracting. fluid. HARRIUIAN
RESEARCH 1,ABORATORY
ROOSEVIILT HOSPITAL. KEW
YORK
.
