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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
outer air a n d , through t h e outer jacket E , with t h e lower receiving vessel. I n t h i s w a y , atmospheric pressure can be restored t o t h e lower vessel without i n a n y way affecting t h e v a c u u m t h r o u g h o u t t h e rest of t h e distilling system. T h e lower vessel can t h e n b e removed, or i t s contents drawn off, as t h e case m a y be. T h e effect of t h i s arrangement of t h e 3-way cock, therefore, is t h a t i n one position only does i t make connection between t h e p u m p a n d t h e lower receiver; a n d in one position only, between t h e l a t t e r a n d t h e outer air. I n all other positions, it merely seals t h e t u b e at D. T h e manipulations are as follows: T h e e n d of t h e condenser (or distilling t u b e ) is inserted through a rubber stopper i n B , a suitable receiving vessel is a t t a c h e d t o t h e funnel s t e m , also b y means of a rubber stopper, t h e p u m p is connected at P , a n d t h e entire a p p a r a t u s evacuated, t h e 'stopcock F being closed, t h e stopcock H open, a n d t h e 3way cock D being t u r n e d so a s t o establish connection between t h e p u m p a n d , through t h e outer jacket of t h e funnel stem! t h e lower receiving vessel. When t h e first fraction has been collected i n d , a n d i t s volume read, i t can be r u n i n t o t h e lower receiving vessel simply b y opening t h e stopcock F . If t h e first (or a n y subsequent fraction) proves greater t h a n t h e graduated capacity of A , t h e l a t t e r can be filled a n d drawn off a s m a n y times as m a y be necessary; or, if preferred, t h e stopcock F m a y be left open during t h e taking of t h e fraction, allowing t h e distill a t e t o r u n right on through A F i n t o t h e lower receiver. After t h e first fraction has all been r u n into t h e lower receiver: t h e stopcocks F a n d H are closed, a n d t h e 3-way cock D t u r n e d so as t o close t h e connection between t h e lower receiver a n d t h e FIG.I1 p u m p a n d open t h a t t o t h e outer air. This allows t h e air t o flow into t h e lower receiver, a n d t h e l a t t e r can t h e n be removed, emptied a n d replaced, or a new one a t t a c h e d . Meanwhile, t h e distillation has not been interrupted in a n y way nor t h e v a c u u m affected, a n d t h e distillate is accumulating i n A . When t h e new receiver is connected below, it is first evacuated b y turning back t h e 3-way cock t o its original position, after which stopcock H c a n be opened again, a n d t h e fraction accumulated in il drawn off as before. If t h e new receiver a t t a c h e d below is large in comparison with t h e capacity of t h e p u m p , a n d t h e operator SUSpects t h a t ' l e a k s may be altering t h e pressure in t h e distilling system (since t h e p u m p is cut off at H ) , he can test t h i s for himself a t a n y moment, without losing a n y of t h e evacuation of t h e lower receiver already gained, b y turning t h e 3-way cock so as t o seal t h e t u b e at D , waiting a moment until t h e pressure gauge has fallen again t o t h e initial pressure i n t h e distilling sys-
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Vol. 7, NO.9
t e m , a n d t h e n slowly opening t h e stopcock H . Any loss of pressure will t h e n be immediately apparent. I n case t h e r e h a v e been leaks a n d t h e pressure has changed, stopcock H is left open until t h e desired .evacuation is restored, after which it is closed and t h e exhaustion of t h e lower receiver resumed. W i t h this a p p a r a t u s , a n y number of fractions m a y b e t a k e n , of a n y desired volume. B y using a separat o r y funnel, or similar vessel, as t h e lower receiver, t h e fractions can be drawn off a t will without removing i t at all. T h e writer has found 2 5 0 cc. a very convenient size for t h e receiver. An a p p a r a t u s of this capacity is a b o u t 1 5 in. high over all, a n d t h e diameter of A is approximately z i n . , so t h a t it is easily held b y an ordinary Liebig condenser clamp. A P P A R A T U S I 1 is a somewhat simpler form, for use in laboratories which, like t h a t of t h e writer, happen t o be equipped with more t h a n one p u m p . T h e 3 way cock D may be set as indicated either in Fig. I or Fig. 11. I n this t y p e of a p p a r a t u s , after t h e removal of t h e first fraction, t h e lower receiver is evacuated b y connecting t h e auxiliary p u m p with t h e hollow s t e m of t h e 3-way cock, after which it is t h r o w n again into t h e distilling system b y turning t h e 3-way cock back t o its original position. Both forms of t h e receiver are manufactured b y t h e Emil Greiner Co., j j F u l t o n S t . , Xew York, N.Y . COLUMBIA UNIVERSITY, NEW PORK CITY
A SIMPLE AUTOMATIC-ZERO BURETTE By A. T. MERTES Received May 7 , 1915
Most automatic-zero burettes discharge t h e overflow f r o m t h e b u r e t t e into a receptacle separate from t h e main reservoir, a n d t h i s excess is either t h r o w n away or is poured back into t h e main supply. For solutions t h a t have been carefully standardized, this practice is inconvenient a n d m a y be a source of error. T h e accompanying drawing shows a n automaticzero b u r e t t e t h a t discharges t h e overflow back into t h e main reservoir. I t has t h e a d v a n t a g e t h a t i t m a y be protected from t h e carbon dioxide of t h e air, a n d hence is especially a d a p t e d for use with s t a n d a r d acid a n d alkali solutions. I t consists of a large Woulfe bottle having a b u r e t t e a t t a c h e d t o i t s neck b y a clamp. T h e b u r e t t e has a side aperture which connects, b y means of rubber t u b i n g , t o a goose-neck-shaped glass tubing, A , a b o u t 5 m m . in bore. This is b e n t in such manner t h a t t h e ring of t h e pinch clamp encircles i t a n d is t h u s prevented from rotating. Half way between t h e b u r e t t e a n d where t h e connection tube, A bends'down i n t o t h e liottle a n inner t u b e , B , is fused. This inner t u b e is about I m m . i n bore. It connects with a short a r m , C, forming a T with t h e main tube. T h e lower ext r e m i t y of t h e inner t u b e B is fused t o t h e outer t u b e a t D i n such a way t h a t it opens outside this t u b e . This prevents air bubbles t h a t m a y be drawn through t h e inner t u b e from rising in t h e main supply tube. T h e t o p of t h e b u r e t t e is closed b y a cork, E , through
Sept.. r g i
j
T H E J O l - R S A L O F I S D L ' S T R I A L .4-IrD ELVGIAVltEERISG C H E M I S T R Y
which is fitted a double tube. T h e outer t u b e is connected b y a short T t u b e , F , bent downward and fitted with a rubber t u b e b y means of lvhich t h e operator sucks u p solution t o fill t h e burette. T h e inner or
E
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01-erflow t u b e G is fused into t h e outer and bends downw a r d , connecting by means of a short rubber t u b e , with a small glass t u b e , H . This t u b e extends d o m i t h e back of t h e burette a n d joins, b y means of another short rubber t u b e , with t h e t u b e C. T h e overflow t u b e G m a y be adjusted b y sliding u p or down in t h e cork E so t h a t t h e lower end of it is on t h e same level as t h e zero mark on t h e burette. It is seen t h a t when t h e liquid above t h e zero mark on t h e burette is allowed t o siphon back it will drain off all t h e liquid above t h e zero mark. I n order t o fill t h e burette, t h e operator opens t h e pinch-cock J a n d sucks through t h e rubber t u b e K till t h e liquid is above t h e zero mark on t h e burette. He t h e n allows t h e excess t o automatically siphon back through t h e overflow t u b e into t h e main supply. I n s t e a d of filling t h e burette b y suction, a rubber bulb m a y be attached t o t h e bottle so t h a t t h e burette can be filled b y air pressure. For small supply bottles this method is excellent b u t for larger ones it is not so satisfactory. 6358 ELLISA v s r u c , CHICAGO,1~1.1~015 ~
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A KJELDAHL DISTILLATION APPARATUS By J. M. PICKEL Received March 6, 1915
M r . Holmes describes what is evidently a n excellent f o r m of Kjeldahl distillation apparatus.' We have 1
THISJOT:RSAL. 6 ,1914). 1010.
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been using for eight or ten years in t h e laboratory of the S o r t h Carolina Department of Agriculture a distillation a p p a r a t u s of t h e writer's designing, which xvould seem t o be simpler, more flexible and less costly t h a n t h a t of XIr. Holmes'. This apparatus has the following features, some of which are, so far as k n o n n t o t h e writer. distincti1-e: I--The connecting bulbs a n d condensing t u l m are in one piece. thus eliminating annoying rubbcr connections. ( I n t h e case of a copper still. t h e whcl.1~ thing is in one piece.) a-The condensing tubes are not clamped, s c r e ~ e d or attached, in a n y way, t o other parts of t h e npparntus: a n d n o t enclosed within a n y other part of the apparatus. ( T o be sure, during distillation. there is. connection with flask a n d receiver.) 3-111 consequence of items I a n d 2 , any condenser c a n , without interfering with a n y other condenser, be instantly removed and another dropped into its place; a n y condenser can. therefore, without d i s t u r b ing its neighbors, be repaired, or flushed out with n-:,ter
FIG.
I-BACK VIEW
OF
KJIXDAIIL DISTII.LIN(: APPIKPTI'.
under a t a p , or air forced into it under water ( w i t h x bicycle p u m p , for example), this latter \operation dis-closing b y air bubbles even t h e tiniest leak (all of o u r condensers are t h u s tested when first p u t into comniission a n d a t suitable intervals thereafter). 4-The condensers adjust themselves autoniaiicnlly t o distilling flasks of different lengths. 5-In case one cares t o set or hang t h e app::ra:us against a mall. t h u s throwing distilling flasks a n d re-. ceil-ers on one and t h e same side, t h e condensers a r c easily adjusted t o t h a t arrangement; b u t t h e recei\,ers are placed a b o e e , not b e l o w , t h e distilling flasks. 6--The distilling flasks, their support a n d heaters (Bunsen burners) are suspended over a trough. 7 in conscquencc of arrangement 5 and 6 , i f . d u r i n g distillation, a distilling flask lireaks, as not inirc-. quently happens. t h e contents of it drop. not o n t h e table, nor on or into a receiver. b u t into t h e trough. which can be easily flushed out with water. S--Regurgitation of liquid from t h e recei\.er 11:ic.k into the distilling flask is precluded. In Fig. 11. upper part. are t h e receii-ers iflnt 1)CJrtnm
