T R E J O U R N A L O F I N D U S T R I A L Ah7D E N G I N E E R I & V G C H E M I S T R Y
4 22
for the test could be n-eighed out and dissolved in a definite quantity of water; ( 2 ) a larger quantity of sugar could be dissolved and the solution boiled down t o a syrup, which could then be tested as a syrup. Under the direction of t h e senior author, Mr. J. 21. Scott in 1913 determined the conductix-ity values of some twenty pure sugars b y both of these methods of procedure. For the first, 1 5 g. of sugar were dissolved in hot water and made u p t o j o cc. a t 2 5 0 ' C. For the second method a solution of the sugar v a s boiled until the temperature reached 219' F. The values obtained were seldom identical; in some instances the former method, in other instances the latter method, gave the higher result. This indicated variation in sampling, and as material suitable for a s t u d y of t h e question of sampling was not immediately available the investigation was laid aside. I t has now been resumed n-ith reference t o the volumetric lead test as n-ell as to the conductivity test Ten of the syrups of the season of 191j used in the work reported in Papers TI and VI1 were used in these new experiments. .4bout zoo cc. of each were. boiled t o 243-245' F.,poured into moulds, and allowed t o stand €or a day or two. The sugars thus obtained were redissolved, boiled t o 219' F. and filtered through cotton wool. The conductivity values and t h e volumetric lead numbers were then redetermined on t h e regained syrups and compared with those found in t h e original syrups. The results are given in Table I. They show no material difference between t h e original syrup and t h a t obtained b y redissolving t h e sugar. This method of applying t h e tests t o maple sugar is, therefore, satisfactory. TABI,EI-COMPARISON
OF
hlo. 10 COXDUCTIVITY VALUE' OriginalSyrup . . . . . . . 107 Syrup . . from % E a r . . . . 106 VOLUXETRICLEADS o . Original S y r u p . , . . . . 5 . 3 SyrupfromSugar. . . 5 . 4
VALUESIN ORIGINALA N D REGAINEDS Y R C P S 13 14 16 18 19 22 27 29 43 .4v.
119 99 106 97 108 112 109 117 125 109.9 119 S9 106 98 106 112 110 113 125 109.4 5 . 3 5.1 5 . 3 5 . 8 6 . 0 5 . 7 5 . 1 5 . 6 5 . 2 5 . 6 5 . 3 5.4 5 . 4 6 . 2 5 . 6 5 0 5 . 5 5 . 8
5.44 5.52
The tests have been applied in the same manner t o 16 sugars of the season of 1913, which were collected from the makers wit11 the syrups reported in Paper 1II.I 7 j-IOO g. of sugar were dissolved, t h e solution boiled t o 219" F . and filtered through cotton ~ 0 0 1 . The conductivity 1-alues found vary from 97 t o 148 and the 7-olumetric lead numbers from j . 1 t o 6 . j . These results are all within t h e limits found in pure maple syrups.? The conductivity values obtained by Mr. Scott b y this same method ( z z pure sugars) are also within the limits found in pure maple syrups. Three sugars collected from grocers in the vxstern provinces of Canada in 1912, tested in like manner! gave the following results: NO.
Conductivity Volumetric Value Lead No. 16 0 146 5.6 ......................... 79 0
1.................................. 2 ..................................
Xos. I and 3 are condemned by the tests, while S o . z appears t o be a.genuine maple sugar. METHOD-DkSOlYe a fairly large representative sample (say IOO g.) of the sugar in hot mater. Boil 1
2
THISJOURNAL. 6 (1914). 216 See Papers VI and VII.
Yol. 8. S o .
j
t o 219' F. (103.9' C.). Filter through cotton wool. Test t h e resulting syrup as directed in Papers T I and T-I1 SU 11M A R Y
Pure maple sugars converted into syrups give conductivity values and volumetric lead numbers within t h e limits found ;n genuine maple syrups MACDOBALD COLLEGE, PROVINCE
O r
QUEBEC
DETERMINATION OF TARTARIC ACID By B. G. HARTMANN, J. R . EOFF A N D M. J IKGLE
Received December 30, 1915
The determination of tartaric acid in numerous soda fountain beverages, grape juices, wines and other food products, has necessitated a modification of the Halenke and Aloslinger method, the provisional method of the Association of Official .igricultural Chemists.l Since modifications of this method presented as reports of the =Issociate Referee o n Wine of the above Association h a r e not t,hus far been available t o many chemists mho may be doing n-ork of this nature, it is considered desirable t o revien- briefly the recent methods for the determinatLon of tartaric acid2 and to give t h e results of a successful search for t h e cause of the discrepancies noted in the determination of this acid. These T-ariations i n results. eyen of t h e same analyst. were noted especially on wines containing free acid and alcoh01.~ Alost of the earlier methods depended o n the precipitation of potassium acid tartrate. the original method being t h a t of Berthelot and Fleurieu4 published in 1889. This method mas modified by Halenke and lloslinger' in 1895. Of t h e numerous methods which have been described for the quantitative determination of total tartaric acid in wines. this method may be considered as deserT-ing first mention as t o simplicity of manipulation, accuracy and adaptability t o varying conditions. This is the method which the authors have still further modified. llagnier de la Source6 was perhaps one of the first t o note t h e fact t h a t when free tartaric acid m-as present the cream of tartar precipitate did not represent the total tartaric acid content. He, however, suggested the' neutralization of one-fifch of the total acidity b y adding standard alkali. This procedure did not give satisfactory results on mines containing much free tartaric acid, such as Catawba and Scuppernong. The Goldenberg method' for :he estimation of the tartaric acid content of argols or crude t a r t a r , consisted in dissolving t h e argols in hydrochloric acid and, after completely neutralizing x-ith potassium carbonate, adding acetic acid t o transf o r m t h e neutral salt t o the insoluble acid tartrate. This procedure, however, was open t o criticism, since (as noted by Lampert and b y Ordonneau? iron U. S. Bureau of Chemiatri-, Dzill. 107 (19121, 86. 62 (1914). 5 2 5 - 7 . 537-40. 553-6, 569-72. 3 B. G. Hartmann, Puoc. A , 0. .4. C., 1914. 4 hZ. Berthelot, Chimie V[lkg6tale et Agricole, 4 (lS89;, 423. in collaboration with 11. de Fleurieu. j A . Haleoke and U ' . Moslinger, Z. anal. Chem., 3 4 (18951, 261. 6 > I,. !I 1Iagnier , de la Source, Ann. c h i n . anal., 1 (18961, 205-6. Zeit. anal. Chem., 47 (1908), 57-59 (from Chemischen FaDvik). S A I . C. Ordonneau, Birll. SOL. c h i n . , 7 (1910), 1034-41. 1
: E . P. Haiissler, Schweis. A p o t h . Z e i l . ,
f
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
M a y , 1916
423
and aluminum, commonly present in argols, t e n d , t o tartaric acid into t h e reaction, so t h a t on t h e addilower t h e result. Heczkol calls attention t o t h e tion of t h e alcohol-ether mixture all t h e t a r t a r i c acid fact t h a t t h e freshly precipitated calcium carbonate is precipitated as t a r t a r . These methods are not tends t o react with t h e neutral potassium t a r t r a t e . considered satisfactory as t h e evaporation is producT h e Marseille method2 was used as a n approximate tive of losses through volatilization of esters a n d possimethod for t h e determination of tartaric acid in argols ble decomposition, a n d acid malates are titrated as a n d depended on t h e precipitation of neutral calcium tartrates1 as are also other acid-reacting substances. This method as given b y Malvezin was also tried out t a r t r a t e from a n ammoniacal solution. T h e most recent precipitation method is t h a t de- in t h e Enological Laboratory, a n d gave concordant . ~ is a n extremely satis- b u t uniformly high results. veloped b y A. K l i ~ ~ g This It has been demonstrated in routine work b y t h e factory procedure a n d , as tried out a t t h e Enological Laboratory of t h e Bureau of Chemistry, gave t h e best authors t h a t t h e Halenke a n d Moslinger method yield of a n y method tried. T h e principle of t h e is unreliable when employed on wines a n d fruit juices method is t h e formation of t h e very insoluble calcium containing a considerable amount of free tartaric racemate under conditions which give a theoretical acid, such as Catawba, Iona, or Scuppernong grape yield from synthetic solutions. When applied t o juices or wines, This is due t o t h e failure of t h e two authentic wines representing t h e extremes in ratio method t o precipitate t h e free tartaric acid quantibetween cream of t a r t a r a n d free tartaric acid, i t gave tatively as potassium acid t a r t r a t e a n d is attriburesults which were ali t h a t could be d e ~ i r e d . ~As t h e table t o t h e reversibility of t h e main reaction (H2T HC1). It has been noted by tartaric acid present in t h e grape a n d t h e commer- KCl I_ H K T cial article derived from i t is always t h e dextro form, t h e authors t h a t t h e addition of potassium acetate t h e addition of a n excess of laevo salt would form t h e for t h e purpose of offsetting t h e disturbing influence HC1 _I racemate, so t h a t b y forming t h e calcium salt under of t h e hydrochloric acid formed (KAc t h e favorFble conditions prescribed, a most efficient KC1 HAC) does not altogether correct this fault, onemethod is developed. This is accomplished b y adding fifth t o one-third of t h e free tartaric acid being lost.* calcium acetate a n d alkaline laevo-tartrate of ammonia Furthermore, t h e addition of t h e potassiiim acetate i n excess, a n d titrating t h e calcium racemate pre- t o wines not containing free tartaric acid has a tencipitate with a standardized potassium permanganate dency t o decrease t h e yield b y dissolving t h e potassolution. sium acid t a r t r a t e . 3 Iron a n d aluminum introduce a source of error in Having t h u s recognized t h a t t h e value of t h e Halenkethis determination which has been corrected b y a Noslinger method was in t h e main dependent upon modification, using a n ammonium citrate s ~ l u t i o n . ~t h e elimination of t h e disturbing influence of t h e hyT h e presence of esters of tartaric acid is also allowed drochloric acid liberated, t h e authors decided t h a t t h e for b y saponification as detailed b y Kling arid Gelin.6 best preventive for t h e formation of hydrochloric The present prohibitive price of laevo-tartrate of acid was t o completely neutralize t h e acidity of t h e ammonia, t h e instability of a t a r t r a t e solution, which wine and t o a d d t h e molecular equivalent of tartaric requires a preservative, a n d t h e need of a microscope, acid for t h e alkali added in order t o convert t h e neuare all factors tending t o inhibit a general use of this tral tartrates into acid tartrates, a n d from this point method in commercial laboratories. on t o proceed as prescribed in t h e Halenke-MosOther investigators have made use of t h e reducing linger method, omitting t h e potassium acetate addiaction of t h e t a r t a r i c acid radical; t h u s Chapman tion altogether. By this procedure no intermediate a n d Whitteridge’ oxidize a bismuth t a r t r a t e precipi- products which might possibly interfere with or ret a t e ; Mestrezat* a n d Kling also finally t i t r a t e with dissolve t h e potassium acid t a r t r a t e were t o be expotassium permanganate. Pozzi-Escotg oxidizes bar- pected, t h u s forming favorable conditions for a ium t a r t r a t e , while Ferentzylo ignites magnesium t a r - quantitative separation of t h e total tartaric acid as t r a t e a n d weighs t h e resultant MgO, b u t Gowing- potassium acid t a r t r a t e . Trials of t h e procedure Scopes’l modifies this method and titrates t h e mag- upon various synthetic solutions of tartaric acid nesium t a r t r a t e with permanganate. a n d its salts proved its superiority t o t h e older Evaporation, with a subsequent addition of alco- method. hol, or alcohol a n d ether, has been advanced b y PasUnfortunately, these experiments are not final teur, Reboul, Magnier de la Source, a n d Malveein. since t h e y were for t h e greater part undertaken on The addition of potassium bromide brings t h e free aqueous solutions. b u t it is quite possible t h a t t h e 1 Arnold Heczko, Z . anal. Chem.. 60 (1911), 73-82. behavior of a wine containing various other ingreM. d’Hector de Rochefontaine, A n n . chim. anal., 1 (1896), 25 dients, such as phosphates and sulfates, may augAndre Kling and L. Gobert. Ann. fals., 4 (1911). 185. ment t h e usefulness of t h e method. J. Assoc. of Offic. AKr. Chem.. 1 (19151. 136. . ,. M. Andre Kling and D. Florentin, PYOC.8th Intern. Cons. A p p l . This modification has t h e decided advantage over Chem., 1 (1912). 237-9. the Halenke-Moslinger method in t h a t , where there M . Andre Kling and E. Gelin, I b i d . . 1 (1912). 251-6. Alfred C. Chapman and Percy Whitteridge, A n a l y s t , 32 (1907), 163-6. is a small amount of tartaric acid present in a wine Note of M . W. Mestrezat presented by M. Miintz, Compt. vend.. 143 (as in ports, sherries, and other fortified wines), t h e (1906). 185.
+
+
+
+
I
5
E m Pozzi-Escot, Ann. chim. anal., 13 (1908). 266-9. Josef V. Ferentzy, Chem. Zeit., 31 (1907), 1118. I 1 L. Gowing-Scopes, A n a l y s t . 33 (1908), 315-19,
M. L. Magnier de la Source, Ann. chim. anal., 2 (1897). 281-3. G. Hartman, Bureau of Chemistry, Bull. 162 (1913), 71. A n n . chim. anal., 1 (1896), 205-6.
* B. 3
T H E JOCR-V'IL O F I N D I - S T R I A L A-VD E S G I L V E E R I S G C H E M I S T R Y
421
addition of the tartaric acid insures a precipitation that otherwise might not occur. H A R T M A X K A K D E O P E UIETHOD
n71rvEs--Neutralize I O O cc. of wine with normal sodium hydroxide. The amount of alkali necessary for neutralizing may be calculated from the acidity of the wine previously determined. T o the neutralized wine add the molecular equivalent in grams, of powdered tartaric acid,' corresponding t o the amount of alkali required for neutralization. -1fter the tartaric acid has dissolved add z cc. glacial acetic acid and I j g. potassium chloride and after solution add 1 j cc. alcohol (95 per cent). Stir until precipitation has started, then allow t o stand over night a t a temperature not ab0T-e I j" C. =Ifter this interval filter the solution through either a Gooch crucible prepared with filter paper pulp or a Buchner funnel of 7 cm. diameter, into which is fitted exactly FOR
l r o l . 8. L o .
TEUPERATURE-The authors also find t h a t temperature a t which the reaction mixture of Halenke-Noslinger method is held for ~j hrs. fluences the precipitation, there being a decided crease in yield of tartrate at low temperatures. T.~BLE 111-EFFECT
OF CIiILLINC O N P R E C I P I T A T I O N W H G N METHOD WAS USED
Temperature C. 5 5
5 17
17 17 17
h
k
GR..~M TARTARIC Xcm Actual Found 0.774 0.792 0.401 0,405 0.698 0.994 0.698 0,497 0.354 0 497 0.357
j
the the inin-
UU\lODIFIED
Per cent Acid Recovered I , .9 79.7 80.7 81,s 70.2 70 2 71 3 71.8
--
Before entering upon t h e final description of t h e methods resulting from these experiments it should be remarked t h a t although other investigators have attempted t o avoid the disturbing influence of mineral TABLEI-DZTERXINATIOXS OF TARTARIC Acrn BP HARTMAXX-EOFF acids b y neutralizing a part of t h e acidity of the wine: 31ETHOD t h e authors h a v been unable t o find records showing Results in Grams Tartaric Acid per 100 cc, Liquid Actual Hand MECHAKICAJJ,Y STIRRED t h a t this has been done with a n y marked degree of SUBSTANCE Content Stirred 30 IIiin. 15 min. success and t h a t the addition of tartaric acid t o t h e Tartaric Acid Solution., , 0.481 . . 0.482 ... neutralized solution for the purpose of precipitating 0.481 ... 0.483 0,241 ... 0:5i8 potassium acid tartrate has evidently not heen pre0,241 ... 0.236 0.241 ... 0 .?38 viously tried 0.120 0.110
0.048 0:042 0.025 0.048 0 042 o.oi2(ai .. California Hock Wine . . 0 . 2 5 4 ( b ) 0.240 0.2S5 ... California Sauterne Wine. 0 . 2 2 1 ( b ) 0 . 2 15 0.21; California Zinfandel Wine 0 . 2 3 3 ( b ) 0.211 0.243 .,. 0.088 0.099 California Sherry Wine ... California Port Wine. . . . , ., 0,113 0,120 . . California Sherry No. 2 . . .,. 0.101 0.100 ... California Port No. 2 . . . . ... 0.120 0.120 . . ( a ) Stirred one hour. ( b ) Content determined by method given on p. 86 of C-. S. Depr Algr , Bureau of Chemistry, Bull 107 (Rev.).
a strong filter paper; use gentle suction and wash three times with 7 cc. of a solution composed of IOO cc. of water, I j g. potassium chloride and 2 0 cc. of 9j per cent alcohol. Transfer the precipitate and paper t o the original beaker with j o cc. hot water. bring t o a boil a n d immediately titrate with N ~ I O sodium hydroxide, using phenolphthalein as indicator. Increase the burette reading b y I . j cc. as a correction for solubility, multiply by 0 . 0 1 j and subtract the tartaric acid added. This wid give the total tartaric acid in the wine in terms of grams per IOO cc. 0 T H E R JI 0 D I F I C .A TI 0K S
snRRIxG-It was noted t h a t stirring until a precipitate actually formed was essential t o the accuracy of the method. By means of the mechanical stirring of solutions the time factor was lessened and i t was found practicable by this expedient t o determine correctly t h e tartaric acid content of a synthetic solution in ~j t o 3 0 minutes. t0 H .A L F - S E L- TR A L I Z A T I 0 N MET H 0D .-x n a t tempt neutralize one-half of the acidity of wine proceeding according t o t h e Halenke-IIoslinger method, omitting TABLE II--DETERMIFATIONOF TARTARIC ACID
I N WINES IF WHICH THE Acxnmy WAS HALF L 7 ~ Experiment h-o. 1 2 3 4 5 6 7 Hartmann-Eoff M e t h o d . . , , , 0,i4 0 . 5 4 0 . 9 9 0 . 7 6 0 . 7 2 0 . 7 8 0 . 8 0 Half-Neutralization Method. 0 . 6 8 0 . 5 0 0 . 9 6 0 . 7 1 0 . 6 3 0 . 7 1 0.77
the potassium acetate addition, gave less accurate results than complete neutralization, from 3 t o 9 per cent less acid being found t h a n was present. 1
The acid used should be pure and well dried.
R O C H E L L E SALT X E T H O D
The tartaric acid required may be efficiently added as Rochelle salt. I n that case the method is based on the following reactions: SaKT HqT = N a H T H K T , and NaHT KC1 = K H T NaCl As Rochelle salt contains exactly four molecules of water of crystallization, i t may be used without drying. For every cc. of normal alkali required for neutralization, add 0 . 141 g. of t h e salt. As only j 3 . 1 7 per cent of the salt is normally tartaric acid, weighing errors are minimized. If this salt is ground or unduly exposed to the air it may lose some of its water of crystallization. I t is: therefore, necessary t o obtain t h e actual acid content a t the time used. This may be done by dissolving I g. of the salt in IOO cc. of v a t e r , adding 2 cc. acetic acid, I j g. KCl, and 2 0 C C . of 9j per cent alcohol, stirring until precipitation starts, and allowing t o stand in an ice box with a maximum temperature of I j" C. The addition of alkali may, therefore. be dispensed with. The following results mere obtained on five samples of grape juice, using t h e proposed method and t h e Rochelle salt method:
+
+
+
+
TABLEIv Grams Grams Rochelle Salt Tartaric Acid in Salt hTo. Added C.031 1 0 776 0.720 2 1.297 0.485 3 0.874 0,665 4 1.199 0.372 5 0.677 ~ Rochelle ~ ,OoO ~ ~ 0.555 Salt
T.4RTARIC
Rochelle
]
FOR G R A P E
JuIcE-Take
Salt
0,624 1.170 0,624 0.620 0.640 ~
...
ACIDI N JCICEUSING Tartaric Acid H.-E. Method 0.627 1.205 0,636 0.638 0.637 ~
j o cc. of the filtered juice
and neutralize with *V NaOH.
After neutralizing make t o I O O cc. volume with distilled water. From this point on, the H.-E. procedure as described under wine is followed, using 20 cc. instead of 1 5 cc. of
~
~
M a y , 1916
T H E J 0 G R N A L 0 F I N D U S T RI A L A iV D E N G I AVE E RI AVG C H E M I S T R Y
425
Solutions indicated in Table V were analyzed b y 95 per cent alcohol. The occlusion of other organic acids with -precipitated pectin bodies a n d cream of different analysts on different dates with t h e results t a r t a r makes t h e use of only j o cc. of grape juice ad- given. TABLE\'-(Results in Grams per 100 cc.) visable for the determination. HALENKE A N D HARTMANN-EOFF METHOD MOSLINGER Half Completely I n case of syrups, fermentation of sugar or a separa-. ~ETERMINATION METHOD Neutralued Neutralized tion of t h e acid therefrom as t h e lead salt' is advisable. 1.96 2.52 Acidity as Tartaric.. . . . 4 . 9 2 1 .so 1.89 Total Tartaric Acid.. , . . 2 . 0 0 I t may be of interest t o mention t h a t Halenke and 0.48 0.048 Phosphoric Acid. . . , . . . . I . 9 1 1.20 1.20 1.20 Caramel b1:oslinger advise a double precipitation in t h e case 0.024 0,024 0.024 Amaranth. . . . . . . . . 5.00 5.00 5.00 Cane Sugar.. . , . . . . of grape juices. FOR ARTIFICIAL PRODUCTS COKTAINIKG F R E E PHOS-
A C I D A N D ALCOHoL-~Thile experimenting with synthetic solutions, containing tartaric acid, free phosphoric acid a n d alcohol, it was found t h a t neither the Halenke-Moslinger method nor the Hartmann and Eoff method gave satisfactory results. Further, it developed t h a t these two methods became less reliable as t h e solutions under discussion aged. This condition ivas found t o be brought about b y t h e formation of ethyl esters of tartaric acid, t h e amount of ester formed increasing with t h e time allowed for t h e reaction. This was shown b y saponifying t h e solution with a n excess of alkali before determining t h e tartaric acid, a complete recovery of the theoretical amount of acid being thereby obtained. I t was also observed t h a t in cases where much free phosphoric acid was present t h e Halenke and Moslinger method fniled t o give a n y precipitate of potassium acid t a r t r a t e whatever, notwithstanding the presence of considerable tartaric acid in t h e solution. These two points, t h e loss of tartaric acid through esterification and t h e failure of t h e Halenke-Moslinger method t o give even approximate results in presence of free phosphoric acid, were made t h e subject of investigation in 1914 by the Associate Referee on Wines of t h e Association of Official Agricultural Chemists, The heretofore unpublished work of five collaborators !vas very satisfactory and fully substantiates t h e findings recorded above. T h e behavior of alcohol a n d tartaric acid in t h e presence of other free organic acids (formation oE esters) is a well-known phenomenon and was pointed out b y Berthelot and Fleurieu in their original paper describing t h e alcohol-ether method. Esterification in p a r t may explain why very old wines, when employing t h e customary methods for determining the total tartaric acid, very often show an exceedingly small amount of this constituent. I t is very important t o know t h e extent- of esterification in artificial products containing free phosphoric acid, alcohol, and tartaric acid, since the ordinary methods may not reveal t h e tartaric acid t h a t is present even in amounts as high as 3 g. per I O O cc. of solution. I t was found t h a t by adding j cc. N NaOH in excess of neutralization t o j o cc. of t h e solution under examination, bringing t o a boil and allowing t o stand over night, a complete saponification could be obtained. The addition of t h e required amount of tartaric acid, dilution t o I O O cc. with water and t h e n proceeding as detailed for wines, yielded quantitative results for total tartaric acid.
PHORIC
C . Schmitt and C. Hiepe, 2. anal. Cham., a1 (1882), 534-41.
Alcohol. . . . .
,
...,
5.00
5.00
5.00
Table V I presents results obtained on three synthet;ic solutions, on the dates indicated. TABLE VI-RESULTS ( G . per 100 cc.) Solution Sumber I.....
HALENKE
AND DATE 1914 ~~OSLINCER 7/20 0.74 8/12 0.64 8/24 0.06 8/26 0.63 10'30 0.00
THREESYNTHBTIC SOLUTIONS AND EOFFMETHOD HARTMANN h-eutralization Preliminary Half Complete Saponification 1.88 1.90 .. 1.69 1.84 .. 1.54 1.76 1.66 1.67 2:oo 1.61 1.65 .. 1.76 ..
ON
1.68
..
The low results obtained by the Halenke and hIoslinger method show t h e necessity of starting the precipitation b y stirring as illustrated b y the results obtained on August 24th, and October 30th. The gradual esterification of the free tartaric acid is shown by the lower results obtained a s t h e solutions aged. BUEEAUOF CHEMISTRY, ~VASHIKGTOX
THE DECOMPOSITION OF THE ORGANIC MATTER OF KELP IN THE SOIL' B y A . W, CHRISTIE Received iXovember 15, 1915
Considerable interest has been evinced of late in t h e possible use of kelp as a commercial fertilizer. Burd' has shown that probably the most practical and profitable way of utilizing kelp would consist in drying a t a low temperature and grinding. The resulting product, in addition t o the valuable potash ( I I .4 j per cent K?O in air-dried kelp ( M a c r o c y s t i s ) ) , contains all the nitrogen and organic matter. Stewart3 has shown t h a t t h e nitrogen (1.18 per cent N in airdried kelp ( M a c r o c y s t i s ) ) becomes slowly available in t h e soil. I n connection with t h e probable use of dried a n d ground kelp as a commercial fertilizer or as a filler for mixed fertilizers, it becomes of interest to learn the fate of the organic matter and whether a n y agricultural value may be assigned t o it. The extent and rate of decomposition of kelp in soil were compared with the following materials which are common sources of organic matter in t h e soil, D ~ z . , manure, straw and alfalfa. P L A N OF E X P E R I M E N T
I n each of 14 glass jars were placed 3 0 0 g. of airdried soil (fine sandy loam from a n a h e i m , California), 1 See also work of U. S. Department of Agriculture on Kelp. [EDITOR'S NOTE.] 2 "Economic Value of Pacific Coast Kelps," Bd1. 248, California Agricultural Experiment Station. a "Availability of Xitrogen in Pacific Coast Kelps," J. Agr. Research, 4, S o . 1 (1915). 21.
