“Oxidizing Agent” and Peroxide in an Otto Cycle Engine Cylinder SYDNEYSTEELE,University of Cambridge, England
S
arrangement was suggested by INCE the early part of the A description is given of the apparatus used nineteenth century chemG. F. C. Gordon, of the Camand the results obtained in experiments on bridge University Engineering ish have been interested sampling the cylinder contents of a Ricardo Department, and consisted of a in the mechanism of the comE. 35 engine, from different parts of the comdouble spiral square thread fonnbustion of hydrocarbons and a pression space and a f different times during the ing two i n d e p e n d e n t spaces, great volume of work has been water t r a v e l i n g t h r o u g h one done, in general either on slow compression, exhaust, and inlet strokes. Using space to the seat and returning comb us t i on u t i l i z in g sealed a slightly acid solution of potassium iodide, through the other. This cooling vessels or a steady flow of gas quantitative estimations were made of a n “oxiserved the d o u b l e purpose of through heated tubes, or on exdizing agent’’ which was assumed to indicate a keeping the valve intact when explosions in a bomb. Since the definite stage in the progress of combustion of posed to heat in the engine cylinadvent of prime movers operatder (the method of construction ing on the Otto cycle and using the three fuels used (benzole, a straight-run involved brazing a t the tip) and hydrocarbons as fuel, the probspirit, and an ethyl gasoline). of chilling the sample after passlem has assumed more than an Mention is made of two theories of combustion ing the seat. T h e v a l v e was academic interest and is now of and fuel-knock in a n engine, and their relation threaded on the outside for 4.75 primary importance to the engito the research reported is discussed. inches (12 cm.) f r o m the tip neer. and screwed into one of the four During each of the four stages of the Oito cycle (suction, compression, explosion and expan- standard spark-plug holes in the engine cylinder: when sion, and exhaust) chemical changes take place in the cylinder the desired position had been reached the valve was locked by contents and in an engine the complete cycle is repeated con- a locking collar, the extreine position being with the valve tinuously with great rapidity. At first sight the time element seat a t the center of the cylinder. Difficulties were enmight be assumed to complicate the problem of determining, countered in making the valve gas-tight: no satisfactory for a single cycle, the intermediate products between a hydro- method of lubricating the stem could be devised, carbon and carbon-air mixture and its products of combustion, but the con- rust were deposited while sampling was in progress, and in tinued repetition enables a small sample to be withdrawn each consequence it was impossible to guide the valve stem for a t cycle a t the same instant and this procedure can be continued least 6 inches (15 cm.) from the seat. They were overcome by until sufficient gas has been collected to perform a chemical turning the valve stem from a rod of tool steel and providing analysis, Slow combustion and bomb experiments can a t it with a hemispherical head (seating into a very narrow mild best only serve as guides in the more practical problems en- steel seat) and a guide formed by a cast-iron piston screwed to the other end of the stem. The piston was lubricated by countered in work on an engine delivering power. This paper describes experiments performed on the Ricardo three screw-down grease cups spaced a t 120” intervals round E. 35 variable compression engine at Cambridge University. the sampling valve and beyond i t a rod, screwed both to Although the investigation was not carried as far as could be the end of the valve stem and to an adjustable collar terminatwished, the results reported seem worthy of being placed on ing in a case-hardened hemispherical head, completed the record as an indication of the possibilities of this type of in- moving part of the valve. vestigation. With the engine delivering power, a small SAMPLING MECHANISM , sample of the cylinder contents was abstracted once each engine cycle from a part of the compression space and at a The valve and the actuating mechanism were fixed to plates point in the cycle, both of which could be predetermined. united by a complicated system of stays in three dimensions When sufficient gas had been collected from the cylinder, a and secured to the engine (Figure 2). Motion was transchemical analysis was performed and (in the latter stages of mitted to the valve stem through a case-hardened cone fixed the work) quantitative estimations were made of an “oxidiz- by setscrew to a rod. This rod was provided with two guides ing agent.” The experiments were suggested by the Univer- and given a reciprocating motion by the engine camshaft sity Research Panel of the Aeronautical Research Committee through a clutch, a variable timing device incorporated with a as the logical outcome of others described in an Aeronautical wheel carrying the crank pin, and a connecting rod. The Rmearch Committee publication (4). Samples had been angle of the cone was chosen to make its surface perpendicular taken from the exhaust pipe of an E. 35 engine while it was to the valve at the striking point, so that the thrust should be rotated by motor (ignition switched off and a high jacket approximately along the line of valve travel. Any side temperature maintained), aldehydes and peroxides had been thrust was taken up by a brass ball (through which the end detected, and it seemed advisable to perform similar experi- of the valve projected) held between the fixed plate carrying ments on an engine delivering power, the samples being taken the reciprocating rod and a small adjustable plate held in from the cylinder. position by three setscrews. As first assembled the arrangement gave a valve opening SAMPLING VALVE of 40” (crank angle), but by employbg a 5-inch (12.7-cm.) From seat to gas outlet the valve (Figure 1) measured a diameter wheel on which was cast a suitable lead balance little over 6 inches (15 cm.) and water cooling was provided weight, and a connecting rod of Duralumin (supplied by for a length of 5 inches (12.7 cm.) from the seat. The cooling Messrs. James Booth and Company of Birmingham, Eng202
May 15, 1933
INDUSTRIAL AND ENGINEERING
land), the time of opening was reduced to about 20". This estimate was arrived a t as follows: With the variable timing device in a fixed position and the clutch engaged, the engine was rotated by hand until the cone came into contact with the end of the valve; 50" (crank angle) later contact ceased, but gas did not escape from the cylinder during the whole of this period. Again with the clutch engaged, rotation was continued beyond the point of initial contact of cone and
CHEMISTRY
203
I. No trace of peroxide was detected, and in what follows the substance preseQt in the engine cylinder which possessed the property of liberating iodine from a slightly acid solution of potassium iodide is referred to as "oxidizing agent." QUANTITATIVE TESTS,COMPRESSIOS STROKE The method of sampling finally employed was developed as a result of observations on the type of reaction taking place between gas from the cylinder and the potassium iodide solution. This reaction was slow and appeared to be complete in about 3 hours, so that i t seemed advisable to arrange for the gas to pass directly from the engine to the test solution and remain in contact with it until the reaction ceased. Two sets of five gas-sampling tubes ( A to E and 1 to 5) were used, each tube being carefully calibrated and a mark made on a strip of paper pasted
FIGURE 1. SAMPLING VALVE
valve; then the clutch was disengaged without disturbing the valve-actuating mechanism, the engine rotated by motor, and the gas outlet from the valve tested for leakage. I n this way it was found that gas emerged from the engine cylinder during the 20" to 40' interval of the 50" contact of cone and valve, so that the position of mean opening of the valve (Figures 4 to 6) was taken as 20" earlier than the crank angle at which contact between i t and the cone ceased. For any test it was sufficient to determine this "mean opening" for but one setting of the variable timing device, which was graduated in degrees of camshaft angle. The apparatus went into operation early in 1929 and was then believed to be unique in enabling samples to be taken both at different times during the cycle and from different parts of the compression space. Not until September, 1930, (I??) did the literature consulted contain reference to a valve with similar scope, though accounts of sampling devices fixed in position in the cylinder $re to be found prior to 1929.
on the side. When gas wag passed in to the mark the A to E set contained gas and 50 cc. of test solution, and the 1 to 5 set gas and 25 cc., this being done to simplify the control correction. (Approximately 200 cc. of gas were collected in each tube of the A to E set, and 100 cc. in each of the 1to 5 set.) Samplingprocedure is illustrated by Figure 3. The vessel V was filled with test solution and with A, B, X, and Y open it was raised until the level of the solution in the sampling tube S was at A. X was first partly closed (gas was forced into S , dis lacing the potassium iodide solution), then opened again and thefevel of solution in S allowed to return to A . This insured that the connection between A and X contained nothing but gas from the cylinder. To obtain the sample X was partly closed, gas
QUALITATIVE TESTS
A pressure-tube connection was made between the gas outlet from the sampling valve and one leg of a T-piece, the two remaining legs being also provided with pressure-tube connections. One of these led to the atmosphere and was fitted with a screw pinchcock, the other led to the sampling apparatus, and by partly closing the outlet to the atmosphere a regulated flow of gas from the engine cylinder was maintained through the sampling apparatus. This consisted of a glass spiral ending in a bulb provided with a drain tap (the whole immersed in a freezing mixture) followed by a series of Arnold bulbs containing selected reagents. TABLEI. QUALITATIVE TESTS,COMPRESSION STROKB (Fuel, Shell straight-run spirit. compression ratio 4.5/1* speed 11001150 r. p. m.: jacket water tern 'erature 6O0 C ' poier, ma$imum 'ossible; fuel-knock, occasional slight. hixture 'fired b y two spark plugs Jametrically o posite, sampling valve h.alf way to the center o f , the cylinder on a perpenjiioular diameter. One inlet valve operated with reduced lift, eventually cut out completely, to avoid contact with sampling valve.) RBIAQENT To DBTECT DETECTED Schiff's Aldehydes Yes Titanic sulfate solution Peroxides No trace Acid potassium iodide solution "Oxidizinp agent" Yes Lime water Carbon dioxide Yes Palladium chloride solution Carbon monoxide NO
Samples were taken a t various points during the compression stroke, the results and relevant data appearing in Table
FIGURE2. GENERALVIEW OF ENGINEAND SAMPLING MECHANISM
passed in until S was full, A closed, and the clutch on the Sam ling gear taken out. A waR then opened, the levels in S and $adjusted to the mark on s,and the sampling tube contained a known volume of gas at atmospheric pressure, in contact with a convenient amount of otassium iodide solution. Throughout the quantitative tests tiis test solution was standardized at 5 per cent (by weight) and each 300 cc. were acidified by the addition of one drop of strong sulfuric acid.
ANALYTICAL EDITION
204
The sampling tubes (containing gas and test solution) and a 50-cc. control solution were kept in darkness until the titration was performed (usually about 3 hours after sampling) and during this time the control solution turned slightly yellow. The iodine liberated from all solutions used was titrated by a solution of sodium thiosulfate (starch being added in the final stage to give a more accurate result), part of the same solution being used also to titrate a known amount of standard solution of iodine in potassium iodide. This standard solution (kept i n d a r k n e s s ) was made by adding an accuratelv measu r e d q u a n t i t y of iodine to a solution of potassium iodide in distilled water, and was used throughout the tests. From the titrations of test, control, and standard solutions, the mass of iodine l i b e r a t e d by the gases from the \ cylinder was readily calculated and it was taken as a measure of L , their oxidizing agent \W,/ c o n c e n t r a t i o n by weight. The figures FIGURE 3. SAMPLING APPARATUS were reduced to 100
\
&%Awy ~
cc. of gas and typical results plotted in Figure 4,grams of iodine ( X against positions of mean opening of the sampling valve in degrees of crank angle. Data not deducible from Figure 4 are given in Table 11.
VOl. 5 , No. 3
before closing A , in order to obtain the sample at a pressure as close as possible to atmospheric. The technic gave very consistent results, figures for typicaI tests being plotted in Figures 5 and 6. Data not deducible from the figures are given in Table 111, from which it will be noticed that certain iodine values are omitted from the curves. This was done only when these values were very far removed from the average. A satisfactorily large proportion (80 per cent) of the total number of readings made in the selected tests has been utilized. TABLE111. QUAXTITATIVE TESTS,EXHAUST AND INLET STROKES (Compression ratio 4.75/1. jacket water temperature, 60°,C * spark advance, 30- 35". Sahpling 4alve a t edge of cylinder, except in &st 16 when it was half way t o center)
TEST 1 2 3
READINQS PLOTTED~ F U ~ L
ENQINE SPEED FUEL-KNOCK R-. m n
4
5 4 4 4 5 5 6 5 3 3 10 3 12 5 13 3 14 4 16 4 a Five readings were observed in each test. b Shell straight-run spirit.
E
1120 1086 1124 1094
Occasional, sljeht Occasional, slight Occasional slight Occasional' slight Occaeionai slight Occaeional' slight Occasional: slight
1100
1122 1110
1096 1076 1080 1074 1074 1086 o
N O W
None None None None None Bensole.
d Pratt's ethyl petrol
SUPPLEMENTARY TESTS Gas from the cylinder was either bubbled or drawn directly through titanic sulfate solution a t all points during compression, exhaust and inlet strokes (engine delivering power) , but no trace of peroxide was anywhere indicated.
STROKE TABLE11. QUANTITATIVETESTS,COMPRESSION (Compression ratio 4 75/1; jacket water temperature, 60' C.; spark advance. 30-35') 7 10 11 12 Test 6" Bb Bb S" Fuel 1056 1032 1044 1076 Engine speed (r. p. m.) Occasional None None Continuous Fuel-knock moderate Cc Ad Ad Sampling valve position 25 18 18 25 Valve cooling water (" C.)
s18:t
a
b
Shell straight-run spirit. Benzole.
E
d
At center of cylinder. A t edge of cylinder.
QUANTITATIVE TESTS,EXHAUST AND
INLET
STROKES
A 180" rotation of the complete variable timing device on its shaft changed the valve opening from compression to exhaust, and smaller alterations enabled investigations to be made over a wide range of both exhaust and inlet strokes. During these strokes the pressure in the cylinder varies from a value sligbtly greater than atmospheric to one slightly less, so the sampling technic had to be changed. The procedure was as follows, 100-cc. ca acity sampling tubes being used (Figure 3) : The vessel V and tEe pressure tube connection to S were filled with mercury and Y closed, 25 cc. of potassium iodide solution drawn into S, and A and B closed. The flexible connection was made between V and S; A , B, and Y opened, and S then contained mercury and 25 cc. of su erimposed potassium iodide solution. $0 sample from the inlet stroke X was gradually closed, the level of the solution in S being preserved by lowering V. When X was completely closed V was lowered still further, drawing the sample from the cylinder until the level of the potassium iodide solution was below the 25-cc. mark on 8. A was then closed, V raised until the potassium iodide solution again reached the 25-cc. mark on S , and B closed. When sampling from the exhaust stroke a simllar procedure was adopted, but the level of .the potassium iodide solution in S was kept above the mark
230
UVIPRESSION STROKE
-
2 50
c,2%+
a0
310
FIGURE 4. COMPRESSION STROKETESTS
A small pipe was screwed into the inlet manifold and samples extracted from here with the engine delivering power, but neither oxidizing agent nor peroxide was detected. The engine was allowed to run until the temperature of the jacket cooling water reached 70" C., ignition switched off, and rotation continued by motor. Samples were taken from the cylinder a t various points of the cycle while the jacket temperature fell to 50" C., but neither oxidizing agent nor peroxide was detected. (This agrees with a similar experiment described by Callendar, 4.) DISCUSSION OXIDIZING AGENT. I n view of the uncertainty concerning the identity of the substance detected and estimated by the liberation of iodine from potassium iodide solution, the term "oxidizing agent" is employed for convenience. The reac-
May 15, 1933
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
tion between cylinder contents and test solution, though it commenced immediately contact between the two was established, was slow of completion, and it is known that varying combinations of aldehyde, exhaust gas containing carbon monoxide and carbon dioxide, and air, were abstracted from the cylinder. Naturally the question arises of possible action between air and/or oxides of carbon and aldehyde resulting in the formation of a product capable of liberating iodine from potassium iodide, but reference to Figures 4 to 6 shows (a) small quantities of iodine liberated during the compression and late inlet strokes, when the largest proportions of air and the smallest of oxides of carbon are to be expected, and (b) small quantities also during the early exhaust stroke when the opposite proportions of air and oxides of carbon are to be expected. This would seem to isolate the oxidizing agent (possibly a nascent aldehyde) as the chief liberator of iodine, and three interrelated assumptions are made, namely, that the appearance of this substance marks a definite stage in the progression of hydrocarbon-air mixture to products of combustion, that liberation of iodine from the slightly acid solution of potassium iodide was proportional to the concentration (by weight) of this substance in the cylinder, and that the same substance was produced a t corresponding stages in the combustion of the three fuels used. With these assumptions, the results yield interesting conclusions. Figures 5 and 6 show that the oxidizing agent concentration increases during the exhaust stroke (l), reaches a maximum early in the inlet stroke (2), and then decreases (3). Combustion of the fuel-air mixture in an engine cylinder is never completed during the power stroke and may therefore be assumed to continue during the exhaust stroke (1). Fresh
FIGURE5. EXHAUST AND IKLET STROKETESTS charge enters the cylinder before top dead center, coming into contact with hot metal surfaces and the hot exhaust gases, and combustion is initiated (2). As the piston moves down on the inlet stroke the continued entry of fresh charge dilutes the mixture in the engine cylinder, accounting for the falling off in oxidizing agent concentration (3). This applies equally well to each of the three fuels used, engine operating with or without fuel-knock. Figure 4 shows that with the engine running on benzole (a nonknocking fuel) there was a uniform, slight increase in oxidizing agent throughout the compression stroke, and while running on gasoline (with and without fuel-knock) the amount of oxidizing agent remained sensibly constant. Comparison with Figures 5 and 6 shows that the amounts estimated for the end of the inlet and during the cornpression stroke are approximately the same, and are small compared with those for the early part of the inlet stroke, indicating that oxidation of the fuel-air mixture does not proceed unless contact with hot metal surfaces (and/or exhaust gas) occurs (IO). The absence of oxidizing agent in the samples taken from the inlet manifold, and from the cylinder when the engine
205
was motored, can be explained by the considerably lower temperatures a t which these samples were obtained. PEROXIDE. The lack of definite coordination of substance sought with reagent employed in the paper already mentioned (4) misled the author into a lengthy search for a true peroxide in the engine cylinder. This matter was discussed in an essay written during the early part of 1930 (11)and the point has since been raised by various writers (1, 2, 8, 9). Liberation of iodine from potassium iodide solution is not conclusive evidence of the presence of a peroxide, but a reaction with titanic sulfate solution is.
01 -100
I -80
I ! & -40
I -zO
I
TOC
I 20
I
44
1
I
60
I
I
IO0
120
Gmh Ayk
FIGURE 6. EXHAUST AND INLETSTROKE TESTS The experiments reported in this paper show definitely a complete absence of peroxide in the engine cylinder under various combinations of widely differing conditions: (a) engine operated on three different fuels; (b) engine operated with and without fuel-knock; (c) samples taken during compression, exhaust, and inlet strokes; and (d) samples taken from different parts of the compression space. They therefore do not support the Callendar “peroxide” theory of combustion and fuel-knock in an engine (4-8). If a peroxide be formed during the initial stages of hydrocarbon combustion in an engine cylinder and if this same peroxide be responsible for fuel-knock, it is strange that (whether fuelknock was present or not) no sign of it could be detected a t any point of the cycle from which samples were taken. If a peroxide were formed a t all it must have been after the passage of the spark (which is not where the Callendar theory postulates, 6) and therefore subsequent to the formation of the oxidizing agent herein described. If it be assumed that the oxidizing agent were an aldehyde the evidence of this paper would support the “hydroxylation” theory, put forward many years ago and recently reaffirmed by Bone ( I ) , in the statement that during the combustion of a hydrocarbon a peroxide may be formed after, or as a concomitant of an aldehyde, but not before. ACKNOWLEDGMENTS The author wishes to thank S. Lees and A. L. Bird, under whose successive supervision the work was carried out in Cambridge, and D. H. Andrews of The Johns Hopkins University (where the author holds a Commonwealth Fund Fellowship) for assistance in preparing this paper. He also gratefully acknowledges the award of a Research Studentship by Christ’s College (1928-29) and a grant from the Air Ministry (1929-30). LITERATURE CITED (1) Bone, Proc. Roy. SOC.(London), A137, 270 (1932). (2) Bone and Allum, Ibid., 134,578 (1932). (3) Bone and Hill, Ibid.. 129,434 (1930). (4) Callendar, Aeronautical Research Committee (London), Reports and Memoranda, iXo. 1062 fl926).
ANALYTICAL EDITION
206
(5) Ibid., p. 31. (6) Egerton, Nature, 122, 20 (1928). (7) Egerton and Gates, Ibid., 119, 427 (1927). (8) Mardles, Ibid., 121,424 (1928). (9) Nfwitt and Haffner, Proc. Roy. SOC.(London), A134,591 (1932). (10) Ricardo, Engineering, 129,738 (1930).
Vol. 5 , No. 3
(11) Steele, John Winbolt Essay, Cambridge University, 1930. (12) Withrow, Lovell, and Boyd, IND.E m . CHEM.,22, 945 (1930)
REWEWED February 6, 1933. Preaented before the Division of Gaa and Fuel Chemistry at the 86th Meeting of the American Chemical Soriety, Washington, D. C., March 28 t o 31, 1933.
Determination of 2,3=Butylene Glycol in Fermentations M. C. BROCKMANN AND C. H. WERKMAN Department of Bacteriology, Iowa State College, Ames, Iowa
T
H% production of 2,3-butylene glycol is a property common to many microorganisms in the dissimilation of carbohydrates and polyalcohols. The glycol has considerable potential commercial importance, awaiting only cheap production. No rapid and accurate method has been described in the literature for the estimation of 2,3-butylene glycol and its quantitative determination has been a matter of concern to those working in the field of fermentations. It has in the past been determined quantitatively by two types of methods: gravimetrically, by isolation and direct weighing, and volumetrically, by oxidation e i t h e r w i t h a k n o w n volume of standard oxidiaing agent or to a product which is determined subsequently. Obviously the first type of method as employed by Neuberg and Nord (7) and Breden and Fulmer (2) is difficult because of the n e c e s s i t y for a quantitative isolation of a pure product. The second t y p e , oxidation of 2,3-butylene glycol, has been effected by bromine, potassium dichromate, and periodic acid. With bromine 2,3-butylene glycol is oxidized to diacetyl; the diacetyl is then determined by the use of Fehling’s s o l u t i o n or by the nickel-d i m e t h y 1 gl y o xime method described by van Niel (8). B r o m i n e oxidation has been found to give inconsistent results by Ruot (IO),Donker (S), Breden and Fulmer (2), and Pederson and Breed (9). A method involving the oxidation of 2,3-butylene glycol, steamFIGURE1. AFPARATUS distilled from wine, with a standard dichromate solution has been described by Fellenberg (4). This method involves several correction factors and is in general inapplicable to fermentation mixtures. The method suggested by Birkinshaw, Charles, and Clutterbuck (1) involving a general oxidation reaction of polyhydroxy alcohols with periodic acid as first described by Malaprade (6) appears to be the most satisfactory. This method, however, involves the extraction of an alkaline solution with ether and the estimation of the volume
U
of standard periodic acid used in the oxidation of 2,3-butylene glycol according to the following reaction: CHrCHOH.CHOH.CHa
+ HI04 +2CHsCHO + HIOa + Ha0
Since 2,a-butylene glycol is only slightly soluble in ether, an extraction in order to be quantitative was found to require approximately one week, during which time II considerable volume of the fermentation mixture was carried over with the ether. The maintenance of a potassium periodate solution a t constant normality is somewhat difficult. The method here prbposed involves the following reactions:
+
+
+ +
CH8.CHOH.CHOH.CHa HI04 +2CHsCBO HIOa Ha0 2CHs.CHO 2NBOH.HCl2CHaCH = NOH f 2HaO 2HC1
+
The two molecules of hydrochloric acid are titrated with sodium hydroxide.
PROCEDURE A 20-50 cc. aliquot of the fermentation mixture (depending on the amount of 2,3-butylene glycol present) is placed in a 500-cc. Kjeldahl flask and 40 grams of anhydrous sodium carbonate are added. The podium carbonate serves the dual urpose of preventing steam distillation of small quantities of tactic acid and of decreasing the solubility of 2,3-butylene glycol in water. During the distillation the volume is kept constant between 20 and 30 cc. One liter is distilled over, taking approximately 1.25 hours. The hydroxylamine hydrochloride solution is standardized by bringing to neutralit to methyl orange, adding an excess of acetone, and titrating d e liberated hydrochloric acid carefulIy with 0.06 N sodium hydroxide. The apparatus consists of a 1-liter Erlenmeyer flask, A , to which is connected a reflux ,condenser, B, which passes into an absorption tower, C, containing a known volume of standard hydroxylamine hydrochloride solution. The whole apparatus is equipped for aeration either by air pressure or by suction. An aliquot (500 cc.) of the steam distillate is placed in flask A and to this are added 10 t o 15 cc. of concentrated sulfuric acid and 100 to 150 cc. of a potassium periodate solution containing about 3 grams of potassium periodate per liter. The reflux condenser is immediately installed and the absorption tower C connected. The contents of the flask are brought slowly to boiling (0.5 hour) and kept boiling for 2 hours, and during this time the apparatus is aerated at the rate of two bubbles per second. The absorption tower is then disconnected and the liquid contents poured into a flask. The tower is washed several times to insure the removal of all the uncombined hydroxylamine hydrochloride. To the hydroxylamine hydrochloride solution from the tower is added a solution of 0.1 N sodium hydroxide until neutral to methyl orange. Acetone (free from acid and alkali) is then added in excess to liberate hydrochloric acid and the volume of standard sodium hydroxide solution required to titrate the
