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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 AN EVAPORATING BATH OF SEA SAND HEATED BY STEAM B Y P. P. I'BTFIRSON
neceivedi-.bruary 24. 1417
The apparatus herewith described has been found so convenient and useful in the laboratories of t h e Department of Soils a t the University of Idaho t h a t i t is thought worth while t o tell other chemists about it. It is made of coils of pipe in a bath of sea sand. The heat is supplied by superheated steam, the flow of which is controlled hy a Sarco steam trap. The tray ( A , Fig. I) is made of No. 24 galvanized iron. Of course, it may be any size. Ours is z it. square and 4 in. deep. B is a coil of iron pipe well fitted so t h a t i t can carry a pressure of 100 t o 1 5 0 lbs. per s q . in. A t the end of this pipe is a Sarco steam trap, C, which allows the escape of steain until a certain temperature is reached when i t closes automatically. The coil B is covered with sifted sea sand of about the size t h a t will pass a 20-mesh sieve and washed free from small adhering particles. It is found t h a t by the use of this bath a much more rapid evaporation can be obtained than with a hot water or steam bath. Aside from this t h e escape of large amounts of steam into the room and the noise often accompanying the same is avoided. T o obtain t h e best results the sand should cover the coils t o the to z in. so t h a t the evaporating dish or depth of I > / ~ casserole may be pressed down into it. When the hot sand is allowed t o come u p on t h e side of the evaporating dish the evaporation is greatly accelerated. A temperature of 140' C. can be obtained in the sand be-
bowever, i t has been found t h a t t o avoid this contamination requires no more care than is necessary with t h e old style boiling water bath or the steam
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bath. Thorough washing of the sand t o remove all small particles makes the avoidance of contamination rather easy. Fig. I1 is a cut of the completed bath. Son, P s a r i ~ i r vLABORAIOKY UNIYQXJiIY
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AN IMPROVED FORM OF A FUMELESS DIGESTION APPARATUS By
3. S . MCHIROUE
Received Pcbruary 23, 1917
In a recent, investigation involving a relatively large nurnlier of nitrogen determinations, it became necessary, on account of t h e lack of flue facilities, to make use of a Sy Fumeless Nitrogen Digestion Apparatus. During the time t h e nitrogen digestions were being made, a number of objectionable features t o this particular apparatus were experienced. The writer has, therefore, enlarged and modified the Sy apparatus in such an advantageous manner as t o consider the changes so made worthy of brief notice in thc chemical Iiteraturc. The chief ooints in which the aooaratus shown in t h e accompanying photograph differs from the Sy apparatus and the advantages gained therehy are as follows: r--Increased capacity. Since most ready-made nitrogcn distillation apparatus provides for 6 distillations t o be carried on a t the same time, there is a saving ol time by having an equal number of digestions provided for. *--The lead pipe and t h e absorption bottle is a more pcrmanent and satisfactory arrangement for controlling and disposing of the acid fumes during digcstion. Practically all the fumes are absorbed in the bottle mhich can be easily emptied and the acid recovered by evaporation, thereby effecting a saving of acid and the corrosive action on the drain pipes as well. The pump used in drawing the fumes into t h e absorption bottle is the ordinary type in general use in Iaboratorics. S-Thc shelf E holds 6 beakers which are placed beneath the lower end of tlie condensing bulbs, and catch tlic acid that drains from the condensing tubes after the digestion flasks are removed. After the digestion is stopped and the flasks become cool, a
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tw-em the pipes. Over the hot plaie, whether lieatcd by a gas flame or electricity, this bath has t h e advantage t h a t there is almost no danger at all of spattering. With the hot plate it is almost impossible to avoid this trouble. The objection t h a t contamination from the sand is likely to take place may be raised and, of course, is t o be taken into account. I n this laboratory,
Vol. 9, No. 7
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Z'tiE J O U R N A L OF I X D V S Z ' K 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
small a m o u n t of concentrated acid adl~erest o the inside of tlic condensing iiulbs, which, after t h e reinovai oi t.l?e digestion fiask, absorbs moisture from
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rirnws the fumes through the water in the wash bottle
C, whcre they are absorbed. The adjnstalilc shelf E holds 6 small beakers, which are placed so as t o catch the few drops of acid that always drain from t.he lower end of the condensing tabes after the digestion iiasks are removed. F indicates the rings which support the digestion flasks. The rings are attached t o a '/%-in. iron rod by means of cismps. The iron rod is attached to the vertical rod of the stand by an adjustable screw clamp. G is a '/#-in. gas pipe carrying the 6 burners placed j in. apart and is attached t o the iron stand a t the base by means of a screw clamp. Although the above apparatus has been in use b u t :i short time, it has worked so well as t o leave but little t o be desired in the way of a fumeless digestion apparatus. D z P A R T X s N T or Cil*nrXC*L
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