Dec., 1917
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 BEPOET O N TESTS
No.
the control or check, untreated. The checks showed 00 chrnge in coior ot texture (a good index of the character of thio grade of n u d e rubber). No. 2 was treated with a I per cent water soivtion of copper Bcetate The reagent produced tnckincss. No. 3 w- treated vith copper acetate solution made acid with LO per cent glacis1 acetic acid. The reagent produced foCkiw88. but net materially greater than in No. 2. No. 4 wm treated with myper acLtafe solution made alkalioe with i o per cent oi atrang ammonia. If reacted strongly with the rubber. giving a hard surince which ezsiiy eceeked. The pmduct resemblcd ‘“perished rubber” (Spiiler’r resin). No. 5 v- treated with lubtiedog nil (containing 25 per cent of rancid vegetabie ail) eanying I per rrzt of dry powdeed copper acetate. No. 6 was trated with the same lllbricating oil a%No. 5 but without copper acetete. Io Nos. 5 and 6 the “immersion” test pieces were spoiled. The test wss tw severe. the ~pedmensbeing destroyed (dissolved in oil). The “drop” tests in both Nor. 5 and 6 showed much action, the oil spread over the cotire surface. Those of NG 5 h i t h copper) showed stronger action than those d No. 6 (without copper). 1 w=
1093
Following these recommendations, t h e City Council appropriated a s u m of money for t h e establishment of a sewage experiment station, a n d a citizens’ committee was appointed t o take charge of t h e work. Prof. C. E. A. Winslow, of Yale University, is t h e chairman of this committee a n d t h e director of t h e experiments. During his absence in Russia with t h e Red Cross Commission, Mr. Henry B. Sargent is chairman of t h e committee. The plant was designed by Prof. S. E. Barney, of Yale University, assisted by Mr. R. H. Skelton. T h e writer is chemist and engineer-in-charge of t h e station, with Mr. W. S. Sturges
OBSERVATIONS l-copper acetate will produce lackinms in crude rubber. 2-The act;*” is proportianat to amount of reagent and time of *eontact. 3-Influenee of light end heat is not as great (compared with darkaer, and a lower temperature) su expected. +The ability of the check samples to “sland W” under the Light conditions indicates the value of Pale Plantation CFepe v*efy 01 crude mbber. 5-The presence of acetic acid did not materially aid in the production of loikinclr. &The presence of ammonia exerted a pronounced influence. The sppedmens, however. exhibited B much different appearance. the miface k d and cracked ?-Lubricating oil (contaitling rnneid vewtable oil) d t b 1 per cent of dry copper acetate gave a greater action than the same oil when used alone.
treated samples should be considered in a separate group as they show results t h a t may arise from washing-mills in bad order. While oils alone exert a powerful action on crude rubber, t h e presence of copper magnifies this action. Results with oil a n d copper on crude rubber coincide with t h e observation of Weber concerning t h e presence oi oil in cloth aiding t h e action of copper on rubber. The action of t h e reagent is proportional t o t h e time of application. The influence of light a n d heat is not is great as expected. This feature of the experiment emphasizes t h e f a c t t h a t copper salts induce tackiness in crude rubber indepen(lent1y of t h e usual causes of this trouble. Considered as a whole t h e work sustains t h e views of Dr. Morgan. CLEVHLIND. on10
.
~~~
.
~
COPPER IN SEWAGE AT THE NEW HAVEN SEWAGE EXPERlMENT STATION By F. W. M o r i c m ~ Received September 21. 1917 R E A S O N S FUR INVESTIGATIONS
I n the summer of 1916 representatives of t h e United States Public Ilealth Service, under the direction of Dr. H . S. Cumming, made an investigation of t h e sanitary condition of New Haven Harbor. They found t h a t i t was seriously polluted by the sewagc and industrial wastes of New Haven. They recommended t h a t t h e taking of shellfish from t h e harbor be prohibited, t h a t bathing be prohibited, and t h a t t h e city take steps t o insure t h e proper disposal of t h e sewage.
FIG. I-ExPs=zxBm
SrrIm~
F ~ GII-BUCBHT. . EL&VITO.
as bacteriologist. Continuous operation started in June of this year. New Haven is an important manufacturing city of i p , o o o inhabitants. The sewerage is on t h e combined system. Wastes from most of t h e larger factories are discharged into t h e East Street sewer, which has a n average dry-weather flow of i3,ooo,ooo gallons per day. Since i t was thought t h a t trade-wastes might interfere with t h e treatment of ibis sewage it was decided to locate t h e Experiment Station at t h e outfall of this sewer (Fig. I). T h e sewer discharges into tide-water and a t high tide t h e sewage is backed u p in t h e sewer for a distance of several blocks. DESCRIPTION OF THE PLANT
The sewage for t h e testing station is pumped by a bucket-elevator, which was erected in a concrete forebay a t one side of t h e ?ewer (Fig. XI). T h e sewage is deflected into the forebay by a galvanized-iron deflector built out nearly t o t h e center-line of t h e sewer, and Rows back into t h e sewer a t t h e lower end of t h e forebay. It was believed t h a t a fair sample of t h e sewage could be obtained in this way, including t h e floating solids and grease, a n d that the suspended solids would not be broken u p to ~3 great an extent a s if a centrifugal p u m p were used. Operation of t h e elevator has shown t h a t it fulfills these expectations. It delivers approximately 1jo,ooo gallons of sewage per day into a hopper-shaped receptacle, from which i t flows over t o t h e station through a wooden fiume
1094
THE JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
supported b y wooden bents. Before flowing into t h e weir-box, where i t is measured, t h e sewage passes through a grit chamber 1 5 f t . long, 1 2 in. deep a t t h e inlet end, 4 in. deep a t t h e outlet end, a n d 4 in. wide, with a detention period of 0.24 minute. T h e veloclty of t h e sewage is checked t o 0 . 7 f t . per sec. a t the inlet end, increasing t o 2. I f t . per sec. at t h e outlet end. This velocity is so high a n d t h e detention period SO short t h a t very litcle grit has been removed from t h e sewage. Following t h e grit chamber there is a butterfly valve in t h e flume which is automatically controlled This butterfly valve b y a float in t h e weir-box. keeps t h e sewage a t a constant level in t h e weir-box, t h e excess sewage being deflected over weirs 4 f t . ,long cut in the sides of t h e flume. T h e apparatus for maintaining a constant level was constructed b y Wallace a n d Tiernan, of New York City. From t h e weir-box t h e sewage flows t o t h e various t a n k s over adjustab!e weirs, small amounts of 10,000 gallons per d a y being measured by 60' V-notch weirs, a larger amount, IOO,OOO gallons per day, b y a rectangular weir 71/2 in. long. ,*--
PROCESSES U N D E R INVESTIGATION
T h e processes being studied are: (I) Activated Sludge, (2) Imhoff, (3) Miles Acid, (4) Screening, (5) Disinfection b y Liquid Chlorine. ( I ) T H E ACTIVATED-SLUDGE E X P E R I U E N T S are on t h e continuous-flow basis. The aerating t a n k is 16 f t . long, 4 f t . wide a n d 8 ft. deep. At t h e bottom of t h e t a n k t h e sides slope at 45' t o a trough I f t . wide, which runs t h e full length of t h e tank. An iron f r a m e in which are cemented I 5 filtros plates is cemented into this trough. T h e air is admitted a t t h e inlet e n d of t h e trough, and t h e water which filters through t h e plates can be drawn off at t h e outlet end. T h e a i r is compressed t o 3 . 5 lbs. pressure b y a Nash Hydroturbine having a capacity of 2 0 cu. f t . of free air per minute, It is measured by means of a Venturi tube. T h e settling t a n k is 4 f t . X 4 ft. in plan, a n d 1 2 f t . deep t o t h e bottom of t h e hopper. This hopper slopes at 60' t o a sump in which is cemented a 3-in. ell connected t o t h e suction of a n air-lift pump, Sludge is pumped back t o t h e aerating tank, where i t is measured in a n orifice box. A baffle 7 l / 2 ft. deep extends across t h e center of t h e settling tank. This baffle was first placed 3 f t . from t h e inlet weir a n d I f t . from t h e outlet weir, b u t t h e upward velocity of t h e effluent carried particles of sludge over t h e out!et weir. Since placing it in t h e center of t h e t a n k no sludge has been lost in this way. T h e theoretical upward velocity is now 2 . 4 in per min. and was formerly 4 8 in. per min. T h e capacity of t h e aerating t a n k is 3100 gallons, t h e settling t a n k 1 1 5 0 gallons. At present, while treating 17,000 gallons of sewage per d a y with 50 per cent as much sludge returned, t h e aeration period is 3 hrs., t h e settling period 66 min. (2) T H E IMHOFF T A N K is 16 f t . long X 4 f t . 6 in. wide X 1 1 Et. 6 in. deep. T h e flowing-through chamber extends t h e full length of t h e t a n k , with gas vents 8 in, wide on each side I t s capacity is 840 gallons,
Vol. 9, No.
12
giving a detention period of 2 hrs., when treating 10,000gallons of sewage per day. (3) T H E MILES T A N K is 16 f t . long X 3 ft. 6 in. wide X 4 f t . deep, having a capacity of 1680 gallons. When treating 10,000 gallons per d a y t h e theoretical detention period is 4 hrs. Liquid sulfur dioxide in cylinders is used for acidifying t h e sewage, supplemented a t times b y gas produced b y a sulfur burner. (4) SCREENING EXPERIMENTS were planned with t h e expectation t h a t a n experimental Riensch-Wurl screen could be obtained, which was t o be operated at t h e r a t e of IOO,OOO gallons per day. I n view of t h e impossibility of obtaining this screen, experiments with a mechanically operated screen had to be abandoned. Fixed screens of 30-mesh Monel metal wire cloth are used in a screen chamber through which raw sewage flows a t t h e rate of IOO,OOO gallons per day. The screens are removed when t h e loss of head reaches 2 ft., a n d are cleaned b y hand. T h e operation of t h e screens is discontinuous, approximately 3,000 gallons of sewage being screened for one experiment. (5) The effluents from t h e Imhoff tank, activatedsludge tank, and screening chamber run through baffled tanks where they are treated with LIQUID CHLORINE. T h e periods of detention are from 2 t o 5 mins. ANALYSES O F SAMPLES COLLECTED HOURLY
Four-ounce samples of raw sewage a n d effluents are collected every hour and combined into composites for chemical analysis. Samples are collected for bacterial analysis as often as time permits. On M a y 7-8, 2 4 samples were collected, one each hour, and a complete analysis made of each sample (Table I). TABLE I-ANALYSES
OF SAMPLES OF R A W SEWAGE COLLECTED HOURLY,
MAY 7-8, 1917 PARTSPER MILLION -NITROGEN2 -SOLIDS-
0'
Cd wo E2 *J
z; 8 A.M. 9 10
11 12 1 P.M. 2 3 4 5 6 7 8 9 10
11 12 1 A.M. 2 3 4 5 6 7
2075 2750 2725 2875 2775 2675 2675 2100 1600 1350 100 47 38 36 37 32 29 23 21
17 14 17 20 1350
76 94 70 90 104 98 66 72 80 48 56 108
72 80 72 70 64 56 48 46 42 42 56 68
--
AVBRAGE1058 70
10.4 7.6 6.0 4.0 4.2 4.0 3.4 3.2 3.6 3.4 4.8 4.2 4.6 5.8 5.4 5.6 4.8 3.2 2.0 1.8 1.6 2.0 3.6 5.4
17.6 14.0 11.0 13.6 12.6 13.6 11.0 10.4 10.8 11.0 12.8 13.4 15.4 10.2 9.0 9.4 7.2 5.6 5.2 3.0 2.4 3.6 10.0 17.0
3.8 2.6 2.4 2.4 2.5 2.2 2.5 3.2 3.8 3.2 2.4 1.4 1.3 1.2 1.6 1.1 1.0 1.1 1.0 1.3 1.2 1.4 1.3 1.2
-4.4 10.4 2.0
pSa 0 100 50 165 4430 4,200 49 445 6178 .. 50 230 5880 4;SOO 100 50 122 5057 .. 51 133 5872 '7O:OOO ,000 .. 50 189 5440 ,000 45 155 4313 9j;OOO 51 107 5583 000 42 87 3325 33;OOO 37 .. 97 2840 540 25.:000 ,000 48 126 52 90 433 .. 50 97 342 49 80 312 262 . . . 1O;OOO 35 65 33 47 230 ... 22 42 170 . . . 1O;OOO 108 .. 15 21 14 18 115 ,.. i:Ooo 15 9 93 92 15o;ooo 1o:ooo 9 14 17 122 15 182 5i:ooo ioo;boo 24 42 34 87 2655 362,000 10,000
;
. ... ...
.. .. ..
.
_-88,500
-
-
37
104 2275
12,100
These results indicate t h a t some trade-waste containing large amounts of chlorides is discharged into t h e sewer from 7 A . M . t o 6 P.M. T h e nitrogen determinations show t h a t t h e sewage is very fresh, t h e ratio, Ammonia-Nitrogen : Total-Organic-Nitrogen, being unusually low. The presence of large amounts of nitrite and nitrate nitrogen also testifies t o t h e fresh-
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 C H E M I S T R Y
Dec., 1917
ness of t h e sewage. T h e alkalinity, oxygen consumed, a n d suspended solids are unusually low. T h e dilute character of t h e sewage is due largely t o t h e high consumption of water in S e w Haven, amounting approximately t o 180 gallons per capita per day. T h e most unusual features of t h e analyses are t h e large amounts of chlorides and total solids, and t h e low bacterial content during t h e daytime. During the week of July 9-16, samples collected a t t h e plant during t h e daytime h a d t h e bacterial content indicated in Table 11. These results clearly show t h e Mon. .. ,.. , .
Tues ... , . , . . Wed , ..
8A.M. 1,500,000 1,080,000 1,670,000 1,100.000 1,125,000
10A.M. 1P.M. 4P.M. 59,000 16,000 225.000 7.500 128.000 5,000 100,000 81,000 7.000 148,000 1.500 12,000 9,000 9.000 42,000 7,100 _68.500 _ - _ _ 800.000* -
.,.. .... . . _, . ._ Average ..... 1,295,000 115.400 14.700 159.000 Sun... .. .. . . . . . 3.355.000 2,275,000 2,535,000 * Factories shut down a t noon Saturday. Thurs..
dissolved in nitric acid, t h e acid driven off on t h e steam bath, and t h e residue dissolved in distilled water. An aliquot portion of this solution was diluted t o 50 cc. in a Nessler tube, a n d I O cc. of alkaline sodium sulfide added. The color developed was compared with t h a t produced by known quantities of a coppersulfate solution containing 0 . 2 mg. of copper per cc., when treated with I O cc. of t h e alkaline sodium sulfide. This method is similar t o t h a t in “Standard Methods of Water Analysis” with a few modifications. The entrance of t h e high chlorides is clearly shown
TABLE11-BACTERIAL CONTENT OF SEWAGE. W B E K JULY 9-16 -TOTAL COUNT. AGAR,20’ c.---GAS FORMERS. 37’
DAY
,
Fri.. , , , . , , S a t , ,, ., , . ,
,
8A.M. 100,000 100,000 100,000 100,000 100,000 , ,
100,000
,
..,
c.-
10A.M. 1 P . Y . 4 P . M . 1,000 1,000 100 I00 1,000 100 100 100 1,000 10 10,000 100 100 100 100 -100- - 10 - 100.000*
1,900 385 17,000 100,000 100,000 100,000
presence of some disinfecting substance in t h e weekd a y sewage. hlthough t h e sewage is found t o be acid a t times, t h e composite samples are never acid, a n d i t is believed t h a t none of t h e above samples for bacterial analysis was acid.
109.5
TABLE111-EFFECT OF COPPER SULFATE O N BACTERIA IN COLUMBUS SEWAGE Johnson and Copeland, 1904 COMPOSITION OF & W A G E Organic Nitrogen Alkalinity Bacteria 6.3 P. p. m. 376 P. p. m. 1,200,000 per cc. P. p. m. TOTAL COUNTO N GELATINAT Z O O C. Cu CONTACT: 0 1 6 24 hrs. 0 1,200,000 1,200.000 6.000.000 14,000,000 5 1.200.000 14.000 700 3,400,000 25 1,200,000 9,500 250 zoo 250 1,200.000 3.000 190 35
to be between Samples 6 a n d 7. Inquiry showed t h a t a large rubber factory in this vicinity was pumping 2 , 0 0 0 gallons of sea-water per minute for condenser purposes, all of which was discharged into t h e sewer. TABLE IV-SOURCE
OB COPPERAND CHLORIDES IN NEW HAVENSEWAGE
PARTS PER MILLION
SOURCE O F COPPER I N SEWAGE
DESCRIPTION Alka- ChlorOF SAMPLE No. linity me 67 54 Near source of sewer.. . . . 144 90 Below munitions factory.. 74 165 134 72 Small branch sewer.. . . . Main sewer.. . , , , , . . ... 71 156 2700 90 Below rubber factory.. . 130 2500 Experiment Station, . . . . .
Gas Bacteria Formers Cop- per cc. per cc. per Z O O C. 37OC. 0.0 990,000 100,000 100 8.8 3,000 1,000 5.6 3,000 10,000 0.0 559,000 100 . . . 70,000 1 . 9 380,000 10,000 1,000 65,000 3.5 53,000 1,000 ...
.
The ignited residue from t h e mat of suspended solids . deposited in a Gooch crucible was usually of a brilliant red color, quite similar t o t h e residue of cuprous oxide obtained in t h e determination of reducing sugars .. . . . . . .. with Fehling’s solution. Qualitative tests of t h e mat .. . for copper were positive. Thi; !ed t o t h e conclusion t h a t t h e disinfection of t h e sewage is due t o copper Between t h e places where Samples I and 2 were salts. collected there is a large munitions factory which emT h e bactericidal action of t h e copper ion is well known. ploys I 5,000 people. This factory manufactures brass Copper sulfate was first proposed as a disinfectant cartridges and cannon shells. I n stamping out these for water a n d sewage by B. Krtihnkel in 1892. It shells t h e brass must be annealed several times, a n d was first used in America by Moore2 and Kellerman after each annealing t h e scale must be removed. i n 1903. Extensive studies were made by Johnson3 T h e shells are washed with hot water a n d dilute a n d Copeland in 1904 a t t h e Columbus Testing Station sulfuric acid after each annealing, 1600 lbs. of acid on t h e use of copper sulfate as a disinfectant for sewage. and 120,000 gallons of water being used per day €or B y treating Columbus sewage with copper sulfate this purpose. The waste goes into catch basins, in they obtained t h e results given in Table 111. These which some of t h e solid particles are removed, b u t d a t a indicate t h a t 5.0 p. p. m. of copper in solution in t h e residual acid wastes, containing copper a n d zinc sewage are sufficient t o exert a marked disinfecting sulfates, go into t h e sewer. Here t h e acid is neuaction. Quantities as low as 2 . 5 p. p. m. were almost tralized b y t h e bicarbonates in t h e sewage, a n d the copas effective as 5.0 p. p . m. when treating t h e effiuents per sulfate is changed to t h e basic carbonate: from a contact bed. In order t o find t h e source of t h e copper and t h e high 2CuS04 ~ c a ( H C 0 ~ ) ~ = C U C O ~ . C U ( O H ) ~ zCaS04 3C02 H20. chlorides in New Haven sewage, samples were collected from manholes a t various places in t h e sewer This basic carbonate is gradually changed t o t h e hyfrom t h e source t o t h e outfall (Table IV). Copper droxide : was determined b y evaporating t h e sample to dryC U C O ~ . C U ( O H ) ~HzO = z C U ( O H ) ~ CO?. ness with 2 cc. of concentrated nitric acid. taking u p Ellmsl has shown t h a t t h e presence of carbon dioxide t h e residue in distilled water, filtering, and adding z cc. of concentrated sulfuric acid This solution was a n d organic matter greatly retards t h e precipitation. electrolyzed between platinum electrodes for 3 hrs. He found t h a t quantities as great as 5 p. p. m. of copat 70’ C., using 3 dry cells as a source of current. per may be retained in solution b y organic matter Experiment showed t h a t all t h e copper was deposited for long periods of time. Since t h e sewage from t h e in this time. The cathode was removed, t h e copper munitions factory reaches t h e Experiment Station in approximately I hour, i t is probable t h a t most of t h e 1 J. Gasbel. und Wasseruws.. 36 (1893). 513. copper is still i n solution. Its germicidal power is in* U. S. Bur. of Plant Industry, Bull. 64 (1904).
+
+
+
* J . Inject. Dis., Sup. 1 (1905), 327.
1J.
N. Eng. Water Works Assoc.. 19 (1905). 499.
+
+
+
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
1096
creased by t h e high temperature of t h e sewage, averaging 84’ F. during August. There is a noticeable correlation between t h e number of bacteria and t h e amount of copper, as shown in Table 111. I n order t o determine whether t h e disinfecting action is greatest a t t h e time when t h e copper content is greatest, samples were collected a t t h e Experiment Station from 6 A.M. t o g P.M., on August IO. Four-ounce samples were incubated a t 20’ C. with
Vol. 9, No.
12
age, and remained colloidal and opalescent. T h e relatively high iron content of the one o’clock sample produced a floc of iron hydroxide which coagulated t h e suspended matter and clarified t h e sewage. The results obtained by incubating diluted samples show t h a t in some cases,notably a t P.M. and 6 P.M.,the diluted samples were decolorized before the undiluted ones. This shows how impossible i t is t o apply t h e “dilution method” for t h e determination of t h e oxygen demand of this sewage. By incubating t h e composite sample of raw sewage with methylene blue, however, i t is possible t o obtain a rough measure of t h e amount of germicide present. The Sunday sewage will reduce t h e methylene blue t o t h e leuco-base within 6 hrs. ; some week-day composites have not produced t h e colorless compound for more t h a n 20 days. The effect of the copper on the various processes being studied remains t o be seen, since operation has not been continued sufficiently long t o allow any conclusions t o be drawn. The company producing t h e copper-bearing wastes has investigated t h e recovery of t h e copper and acid, and claims t h a t such recovery would not be profitable because of t h e great concentration necessary. If t h e wastes interfere seriously with the solution of t h e sewage disposal problem, their removal will probably be considered again. The writer wishes t o express his thanks t o Mr. Sturges for t h e bacterial d a t a contained herein, and t o Prof. Winslow for suggestions and advice. S E W A G S EXPERIMENT STATION NEWH A V E N , CONNECTICVT
TANNIN CONTENT OF PACIFIC COAST TREES By H. K. BENSONAND FRANK M. AM
Time RG.
EM.
111
methylene blue, t h e time required for decolorization being a rough measure of t h e strength of t h e disinfecting action. Diluted samples were also incubated, and bacterial counts made (Table V and Fig. 111). TABLE V-DISINFECTION OF PARTS PERMILLION
AUG. 10, 1917 BacGas Formers METHYLENE BLUE teria per CC. Cop- Undi- 1 sewage per cc. Chlor- Alka370 c. ine linity Iron per luted 2 water 20” C. 6 3,700,000 100,000 120 0.1 0.56 30 94 24 6 1.52 3750 136 0 . 2 2;500:000 1 ,000: 000 72 24 1.36 3100 160 5 . 0 120 48 1 . 8 2.88 2900 101 19,000 100 192 168 2800 43 0.3 4.80 144 60 2750 114 0 . 4 2 . 7 2 559,000 1,000 168 144 4 . 0 0 0.2 2800 98 240 240 5.5 5.60 3075 6 187,000 10,000 72 1.92 24 0.6 3200 86 120 24 ..... ..... 1.60 3325 91 0.7 39,000 100 96 48 1.92 88 0.2 3375 144 ..... 150 3.52 3450 9.3 0 . 1 45,000 1,000 100 216 130 103 0 . 4 2.88 80 72 95 63 1 . 4 1.28 33,000 1,000 96 0.64 24 0.2 52 92 ..... 6 24 0.0 0.44 50 96
.
Time 6 A.M. 7 8 9 10 11 12 1 P.M. 2 3 4 5 6 7 8 9
JONES
Received August 28. 1917
SBWAGB BY C O P P E R ,
HOURS
..... .....
..... .....
.....
.....
.....
.....
.....
T h e time of decolorization varies directly and the alkalinity and bacterial content vary inversely, with t h e amount of copper. The physical appearance and tests showed markedly t h e effect of t h e copper. The samples collected a t 6 A.M., 8 P.M., and g P.M. became septic within a few days, developed a strong odor a n d lost their colloidal appearance. The remaining samples, with t h e exception of t h e one collected a t I P . M . , retained their original odor, t h a t of fresh sew-
I n a previous article it was shown’ t h a t the tannin content of Douglas fir slabwood when properly selected contained sufficient tannin t o be considered a suitable raw material for t h e extract industry. I n order t o ascertain what other species common t o t h e Pacific Northwest might be available for extract manufacture this s t u d y was undertaken. M E T H O D S O F E X T R A C T I O N A N D ANALYSIS-The Samples in each case were taken from four or five trees of t h e same species, were first chipped in a Mitts & Merrill “hog”, carefully quartered and t h e final sample finely ground in a Koerner drug mill. The extractor was of t h e same t y p e as used in t h e previous study, extraction carried on for 16 hours and analyzed according t o t h e method of t h e American Leather Chemists’ Association (1914). All calculations are made on a moisturefree basis. E F B E C T OB S E A S O N I N G O N D O U G L A S FIR
T h e sample of sawmill slab reported in t h e previous s t u d y (1. c.) was still available, having been kept in a loosely stoppered jar. It was thought of interest t o ascertain its tannin content after a year’s storage. T h e average of seven analyses is given in Table I for comparison with previous results. From these results, i t would seem t h a t t h e effect of seasoning is t o bring about hydrolysis and possibly 1Tms JOURNAL, I (1915), 915.
