c
T H E J O U R N A L OF I N D U S T R I A L A N D EA’GIn’EERlhTG C H E X I S T R Y .
606
ings were added to portions of the soil at the rate of 5 tons per acre. Treatments with stable manure, extracted with petroleum ether and also in its natural condition, were included in the test as a means of comparison with the samples of sweepings. The plants were grown in the paraffine pots for 30 days, then the green weights were taken. Three pots were ’used for each treatment. The growth is given in Table IV.: TABLE IV.-EFFECT
OF
STREET SWEEPINGS, AFTER PETROLEUM ETHER.
BEING
EXTRACTED WITH
Green weight of
Aug., 1912
terial here mentioned, there are probably other more strictly physical effects due t o the coating of soil particles, thus interfering with normal moisture movements and solubility of the mineral soil constituents. Vegetable or animal oils undergo changes in soils under the influence of soil organisms, but so little is known concerning the action of organisms on the strictly hydrocarbon oils t h a t no statement concernlng the possible disappearance or change of this oil in street sweepings can be made. BUREAU OF SOILS, WASHISGTON,D. C.
7 -
1,910
Radish. Grams. 3.700
2.270
5.400
2.270
5.700
Soil decomposed sweepings, extracted (Sample.Xo. 3). . . . . . . . . . . . . . . . . . . . . . . . . . . 2.190 Soil stable manure, extracted. . . . . . . . . . . . . . 2.260 Soil stable manure, natural.. . . . . . . . . . . . . . . 2.270
5.200 5.800
Treatment.
+ +
.........................
Soil hand sweepings, extracted (Sample No. 1)................................... Soil machine sweepings, extracted (Sample
No. 2) ...................................
+
+ +
Wheat. Grams.
5.700
An examination of the figures in the table shows t h a t the sweepings and stable manure had about the same efficiency in causing increased growth; this is true with both the grain and the vegetable crop. The oil was also extracted from the sweepings by using ether as the solvent and the sweepings afterwards tested in soils. This test also showed t h a t the sweepings were practically as good as the stable manure. It will be recalled t h a t the effect of the unextracted sweepings was not nearly so good as the effect produced by the stable manure. I n other words, after the oil was removed from the street debris its action was practically the same as t h a t of the stable manure. That the oil is the deleterious constituent of the sweepings is also borne out by the fact t h a t the oil itself, when added to culture solutions in which plants were growing, markedly reduced their growth. The application of street sweepings to soils will undoubtedly have a beneficial effect and be a factor in building up the land; the possible danger of a harmful effect from the oily substance which it contains must, however, be considered. If the oil could be economically extracted this danger would be averted. The oil in the d6bris for the first year or two may not have any effect, but a continuous application t o a field year after year may eventually impair its productiveness, unless through drainage or other natural agencies the oily material is drained off or changed. In some localities this is probably the case, as the use of such material is still said to be effective, although i t has been applied for a number of years. N o very definite field information on this point is, however, a t hand. I n this connection attention must be called to the fact t h a t the presence of an unusual amount of oil in such street sweepings has been the result of automobile traffic, and hence appears only in recent years as a n appreciable factor in the use of street sweepings as fertilizer, and it is not improbable t h a t the amount of oil will even further increase in the next few years. Aside from the physiological action of the oily ma-
INORGANIC PHOSPHORUS I N P L A N T SUBSTANCES-A M E T H O D OF ESTIMATION. BY R. C COLLISON. Received Mal 15, 1912
I n the synthesis of organic phosphorus compounds by the plant and their storage in seeds as reserve food, the inorganic phosphates play an important part. The phosphorus used in this synthetic process is taken into the plant in inorganic form and used in the building up of complex organic phosphorus compounds such as lecithins, phospho- and nucleo-proteids and salts of phytic acid. It is believed by some investigators t h a t unmodified plant tissue and a large number of the seeds contain practically no phosphorus in inorganic combination. Since inorganic phosphate is the starting point in the synthesis of organic phosphorus compounds and as there exist in the plant enzymes which have the property of splitting off inorganic phosphorus from such compounds, i t would seem probable t h a t a t least a n appreciable quantity of phosphorus in inorganic form might be found in such plant tissues and seeds. I t is doubtful whether the failure to demonstrate the presence of appreciable quantities of inorganic phosphorus in seeds has been due to its absence in the plant substance under examination or to analytical methods, which may be questioned from a chemical and practical standpoint. Methods of estimating inorganic phosphorus in plant substances usually begin with some means of acid extraction of the material, with subsequent separation of the phosphates from the extract. Some of the proposed methods may be questioned on the ground of mechanical imperfection and also because they do not take into sufficient consideration the influence of organic matter on the precipitation of phosphates with the common precipitating agents. This influence on precipitation was investigated, t o some extent, by the author two years ago.1 Dilute acid extracts of plant substances contain, besides inorganic salts, also proteids, carbohydrates and, in the case of cereals, salts of phytic acid. The proteids and carbohydrates both inhibit the formation of ammonium-phosphomolybdate, and the salts of phytic acid especially have the property of suppressing the formation of this precipitate in a marked degree. The influence of phytin, especially, was investigated by the author two years ago. That it is no 1
Bull. 216, Ohio Agr Exp. Sta., April. 1910.
Aug., 1912
T H E JOL-RAYTL-lL OF I,\-DCSTRIAL
small factor contributing t o the accuracy of the final results can be readily appreciated when the results below, which were secured c t t h a t time, are examined. Commercial phytin was dissolved in 0 . 2 per cent. nitric acid and pure sodium phosphate, equivalent t o 0 . 0 4 2 0 gram magnesium pyrophosphate, added. Acid molybdate solution in excess was then added and t h e solutions digested at 60' C. for one hour. The volume of the solutions was about zoo cc. TABLEI.~-INFLUENCE O F PHYTINO N Grams phytin. 1 0
0 5 0 4 0 3 0 0
THE
215, Ohio Agr E x p . S t a .
TABLE II.--ToTAL
ASD
INORGANIC PHOSPHORUS IN
607 A
FEW PLANTSUB-
STANCES.
Total phosphorus. Substance. Per cent. 0.397 Oats, g r a i n . . . . . . . . . . . . . . . . . . . . . . . TVheat, grain. . . . . . . . . . . . . . . . . . . . 0 . 3 9 1 0.266 Corn, g r a i n . , . . . . . . . . . . . . . . . . . . . . . Soya beans.. . . . . . . . . . . . . . . . . . . 0.547 Cow p e a s . . . . . . . . . . . . . . . . . . . . . . 0.445 Rice polish., . . . . . . . . . . . . . . . . . . . . . 0.600 0.230 A l f a l f a hay... . . . . . . . . . . . . . . . . . . . . Blue g r a s s . . . . . . . . . . . . . . . . . . . . 0 . 2 5 6
Inorganic I>hosphorus. Per cent. 0 060 0.036 0.041
0.054
0.056 0.027 0.136 0.158
PRECIPITATION O F PHOSPHORUS Grams pyrophosphate recovered. 0 0000 0.0260 0.0329
0.0371 0.0420
Phytin is only one of the substances present in acid extracts of seeds, which m a y have a retarding or inhibiting influence on the precipitation of phosphorus. Large quantities of some salts of organic acids seem t o have this tendency. Alkaline citrates, solutions of which seem t o have the property of dissolving phytin, have tendencies in this direction. These results, it is believed, indicate very clearly t h a t failure t o demonstrate the presence of inorganic phosphorus in some of the seeds may easily have been due t o discrepancies in the analytical methods. There is no absolute standard with which we can compare results b y different methods. The only standard we have for comparison is one established b y the addition of a known quantity of pure phosphate t o a plant substance, together with the constancy of our analytical results. Complete recovery of the phosphorus added and a constant result for inorganic phosphorus without such addition constitutes t h e most reliable test we have at present of any given method. The difficulties in precipitation above noted have been, t o some extent, overcome b y some previous work two years ago.' A brief description of the method published a t t h a t time is here given. Ten grams of the substance are extracted with 300 cc. of 0.z per cent. hydrochloric acid for three hours: 2 5 0 cc. of the filtered extract are precipitated with magnesia mixture and made strongly ammoniacal. After I z hours the precipitate is filtered off and washed with ammonia and finally with alcohol. The dried paper with the precipitate is thoroughly shaken with a measured volume of acid alcohol, the mixture filtered, a n aliquot of the filtrate evaporated and phosphorus determined in the residue. This method avoids the necessity of precipitating phosphorus in the presence of proteids and salts of phytic acid. I t has now been in use for two years in this laboratory and has given more satisfactory results t h a n any method previously used. I n all the plant substances examined from time t o time, appreciable quantities of inorganic phosphorus have been found by this method. A few results are here given for illustration:
* Rzrll.
A N D ENGIXEERIXG CHEAIISTRY.
With substances giving extracts low in organic material, as is the case with the rough feeds, such as the hays, and also with many other substances, the method gives very consistent results. With substances giving extracts high in organic material, this method may cause high results due to great difficulty in filtering the extracts, the prolonged standing probably causing decomposition of organic phosphorus compounds, and in other cases low results due t o the influence of organic substances on precipitation of magnesium-ammonium-phosphate. These difficulties are met with especially in t h e extracts of leguminous seeds, cereal grains and their byproducts, which are in general very difficult t o filter. With the purpose of eliminating these sources of objection a new method is proposed, which, although bearing some resemblance t o the old method in its minor details, is quite different as regards extractive medium and method of precipitation. While investigating the solubilities of inorganic and organic phosphorus compounds in connection with the acid water extraction method, the author found t h a t cold acid alcohol (94 per cent. alcohol containing 0 . 2 per cent. of hydrochloric or nitric acid) has the property of dissolving the common phosphates, which are insoluble in neutral or slightly alkaline alcohol. Froteids in general, nucleinic acid from yeast, carbohydrates and salts of phytic acid appear for the most part t o be insoluble. Taking these facts into consideration, a n acid alcohol extraction bf the material is proposed. Such a n extraction would insure solution of inorganic phosphates, which could be filtered from the undissolved organic phosphorus compounds in the residue. For the investigation of this proposed method of extraction and separation three plant substances were selected. ( I ) Soya beans, on account of their high percentage of soluble protein and also because dilute acid water extracts of the ground beans, as well as the precipitated extracts, are extremely difficult t o filter. ( 2 ) Rice polish, on account of its rather high content of phytin ( 3 ) Corn germ meal, on account of its content of nuclein phosphorus. The method of procedure and t h e new method in detail, as proposed, is as follows: N E W M E T H O D O F ACID A L C O H O L E X T R . i C T I 0 N IB D E T A I L .
A ten-gram sample of the substance, very finely ground, is placed in a 400 cc. Florence flask and covered with exactly 300 cc. of 94 t o 96 per cent. phos-
608
T H E JOGRIYAL OF IiYDL-STRIA L A N D En'GI-\-EERI-YG
phorus-free alcohol, which contains 0 . 2 per cent. of hydrochloric acid (calculated from the per cent. HC1 in the concentrated acid). The flask is shaken a t intervals of five minutes for three hours. The extract so obtained is then filtered through dry double 11 cm. filters into dry flasks. No suction is necessary. An aliquot of z j o cc. of this filtrate is placed in a 4 0 0 cc. beaker and made just alkaline t o litmus paper with ammonia. A slight excess of ammonia does no harm. The solutions are allowed t o stand 8 t o 1 2 hours or overnight and then filtered through double 11 cm. filters, care being taken t o decant the clear liquid as long as possible. The precipitate is then transferred t o the filter and washed w-ith 94 t o 96 per cent. alcohol, which has been made very slightly ammoniacal. I n transferring the precipitate, some of the material may stick very tenaciously t o the beaker. I n this case, after cleaning the beaker fairly well, add 5 drops of hydrochloric acid to the beaker, rub out the latter with a rubber tipped rod, add I O cc. of alcohol and then make just alkaline with ammonia and transfer this last portion t o the filter. I n this way the last traces of the precipitate can be easily removed. After washing several times, the inner filter with the precipitate is spread out and allowed t o dry completely. It is then transferred t o an Erlenmeyer flask containing exactly IOO cc of o j per cent. nitric acid in water (calculated from the per cent. HXO, in the concentrated acid). The flask is stoppered and the contents thoroughly shaken until the paper and precipitate are broken up. It is best t o let stand for some hours. The material in the flask is then filtered through dry double 11 cm. filters into dry beakers and exactly 7 j cc. of the filtrate precipitated with j o cc. of official acid molybdate solution in the usual 7%-ay. Ten grams ammonium nitrate and two hours digestion at 60 O C . are usually sufficient. The final result represents t h e amount of inorganic phosphorus in 6 . 2 5 grams of the original sample. I t is advisable t o reprecipitate the pyrophosphate, if the final solutions are highly colored, which is sornec times the case with some of the rough feeds, as the hays. I n the case of substances which are relatively high in inorganic phosphorus, a smaller sample may be taken, 3 t o 6 grams. I n using this method with substances which are tenacious and gummy, and which do not break up readily in acid alcohol, as is true of dried fruits and other substances containing considerable sugar, the same may be worked up TTith sand and a definite quantity of water, 1.j to 2 0 cc., is usually sufficient. This may be done in a mortar and the material washed out into the flask with acid alcohol, care being taken to use the correct volume, namely, 300 CC. minus the quantity of water used, This method deflocculates the most refractive substances in this regard. It is also very important t o have the original material ground as fine as possible before extraction. Three sets of determinations were made by this method on soya beans, rice polish and corn germ. I n each case determinations were made with and without the addition of a known amount of pure phos-
CHEL1-IISTRY.
Aug.,
1912
phate, in an endeavor t o recover the latter completely. The first two sets of results were slightly low, due t o insufficient time given for precipitation, since the filtered extracts were made ammoniacal and filtered immediately. Following the detailed method as stated, allowing the extracts after precipitation t o stand the specified 1 2 hours, very consistent results were obtained as shown by the following table: TABLEIII.-RECOVERYOF
A D D E D PHOSPHORUS
TRACTIOS
BY
ACID-ALCOHOL EX-
METHOD.
With phosphate 0.0037 TheoPer cent. Without gram phos- retical inorganic phosphate. phorus. results. phosphorus.
Substance.
Soya beans . . . . . . . . . , . . 0 . 0 0 1 5 Rice polish . . . . , , . . . . . 0.0012 Corn germ . . . . . . . . . . . . . 0.0018
.
0.0053 0.0048 0.0053
0.0052 0.0048 0 0054
0 024 0,019 0.028
The figures are grams of phosphorus (element) and are averages of three determinations. The first column of figures represents the quantity of inorganic phosphorus found in the material itself. Column 2 represents the amount found after the addition of pure phosphate in known quantity, and column 3 the results which should have been obtained after adding pure phosphate, assuming t h a t the figures in column I are the correct ones for inorganic phosphorus. For example, the inorganic phosphorus in 6 . 2 j grams of soya beans amounted to O . O O I ~ gram phosphorus. To every 6 . 2 5 grams of sample were added pure sodium phosphate equivalent to 0.0037 gram phosphorus. Thus, if the added phosphorus were completely recovered, the result should have 0.0037 = o . o o j 2 gram phosphorus been 0.0015 for the theoretical. These results check with the theoretical as closely as could be desired, indicating complete recovery of the phosphate. I n Table I V are given similar results on a more extended scale. The pyrophosphate was reprecipitated, the results being given in column 3.
+
TABLE IV.-INORGANIC PHOSPHORUS BY NEW METHOD,WITH
ASD WITHOUT
PUREPHOSPHATE. With With phosPer cent. phosphate phate reinorganic Without 0.0037 gram precipi- Theoretical phosphosphate. phosphorus. tated. results. phorus.
Substance. Cow peas . . . . . . . . Oil m e a l . . . . . . Cornmeal ...... \\-heat, grain.. . . \\;heat b r a n . . . . . \Theat germ. . . _ . Clover h a y . . . . . . Timothy h a y . . , . Oats, grain . . . . . . Cottonseed meal. Rice p o l i s h . . . . . . Corn germ . . . . . . Soya beans . . . . . .
..
.
0.0014 0.0017 0.0016 0.0008 0.0021 0.0025 0.0043 0,0030 0.0026 0.0014 0.0012
0.0018 0.0015
0.0053
0.0057 0.0056 0.0046 0.0063
O.OOG8 0.0085 0.0068 0 0067 0.0055 0.0050 0,0055 0.0053
0.0051 0.0053 0.0051 0.0044 0.0060 0.0064 0.0082 0.0067 0 0064 0.0053 0.0049 0.0055 0.0052
0.0051 0.0054 0.0053 0 0045 0.0058 0.0062 0 0080 0.0067 0 0063 0.0051 0 0049 0.0055 0.0052
0.023 0.027 0.025 0.012 0.034 0.040
0.070 0.047 0.041 0.023 0.019
0.029 0.024
The figures represent grams of phosphorus (element). Here again the results agree with the theoretical in every case. The extracts of substances which by the acid water extraction method filter with great difficulty, by the acid alcohol extraction method filter with great ease, as well as the solutions after precipitating by neutralization.
Aug.,
1912
T H E JOL-R.\-.AL
OF I S D L - S T R I . 4 L A.\-D
I n order t o make the comparison'complete. a similar series of determinations mas made bj7 the acid water extraction method cn the same substances, with and without phosphaLz added. TABLE\~.-CO>SPhRISOS METIIODS.
O F .%CID XvATER A N D A C I D .4LCOHOL BXTR.%CTIOS
RESULTS BY
A C I D \\-.%TER
l!ETHOI).
Per cent. inorganic Per rent. phos\Vith inorganic phorus, phosphate. Theo- phosphate, acid \Vithout 0.0081 gram retical acid water alcohol Substance. phosphate. phosphorus. results. extn. extraction. Cowpeas . . . , , . . . . 0.0013 0 0065 0.0094 0.020 0.023 Oil m e a l . , , , . . . . Cnfilterable 0.027 Corn meal _ . . . . .. . 0.0014 0.0092 0.0095 0.022 0.025 0.0074 0.0057 0.009 0.012 W h e a t , g-rain.. . . . 0.0006 0.0098 0 . 0 115 0.059 0.034 Wheat b r a n . , . . . . 0.0037 . . 0,0022 0 0090 0.0103 0 035 0.040 Clover h a y . . . . . . . 0 0037 0 0088 0,0118 0.059 0.070 Timothy h a y . , , . . 0,0026 0.0105 0.0107 0.042 0.047 Oats, grain . . . . , . . 0 0034 0.0110 0,0115 0'.055 0.041 Cottonseed m e a l . . 0 . 0 0 4 8 0.0124 0.0129 0.076 0.023 0.0087 0.0097 0.025 0.025 Rice polish , . . . . , . 0 0016 0.029 0.029 0.0097 0.0099 . . 0.0018 0.015 0.024 0.0032 0.0047 . . 0.0010
The results in t h e first three columns are expressed in grams of phosphorus (element). The inorgan'ic phosphorus was recovered in five cases, namely, corn meal, timothy hay, oats, cottonseed meal and corn germ. I t is interesting in this connection t h a t all five are substances which do not give a large quantity of organic material on extraction. On the other hand, cow peas, wheat. wheat bran, wheat germ, clover hay, rice polish and soya beans are all plant substances which yield a large quantity of soluble organic matter on extraction, which has evidently had its effect in preventing complete precipitation. since the phosphate added was not entirely recovered in these substances. Hydrolysis has possibly been a factor contributing t o the variations in t h e results by the two methods, especially in the case of cottonseed meal and wheat bran.% The higher results in these two substances may indicate the splitting off of inorganic phosphorus from organic compounds. This factor would have considerable bearing on results b y the old method, in which extraction and precipitation is made in a water solution. On the other hand, in the new method this factor would not have special significance, since extraction and filtration are made in alcohol and the presence of strong alcohol practically throughout the process tends t o prevent enzyme action and bacterial decomposition. As a factor in causing lorn results may be mentioned
E.YGIiVEERIA'G C H E A I I S T R Y .
609
the property of some organic bodies t o combine with inorganic salts in water solution and also the property of such bodies of inhibiting the precipitation of phosphorus, either chemically or mechanically. Phytin, proteids and carbohydrates seem t o have these properties, some in a marked degree. The chief considerations which recommend the acid alcohol extraction method may be stated as follows: ( I ) Alcohol extractiop tends t o prevent enzyme and bacterial decomposition of organic phosphorus compounds. ( 2 ) Organic phosphorus compounds in general seem t o be practically insoluble in the solvent. (3) Filtration of the extracts of even the most difficultly filterable materials is very rapid. (4) Recovery of the alcohol used is possible. ( 5 ) A considerable saving of time over the old method is secured. (6) Results on all the substances examined seem to be consistent and in all cases added inorganic phosphorus was completely recovered. The author does not claim t h a t the acid alcohol extraction method gives final and absolute results for inorganic phosphorus in vegetable substances, but hopes t h a t i t may be useful in more nearly approximating the truth. Lack of time has prevented further work on some of the details of the method, such as the influence of a longer time of extraction or a slightly stronger acid, and the substitution of a second acid alcohol separation t o take the place of the dilute nitric acid separation in the Erlenmeyer flask, details which might he of considerable interest. I t is also thought t h a t this method might be adapted t o the determination of inorganic phosphorus in animal tissues. Tissues dried by vacuum could be extracted by acid alcohol, either before or after ether extraction of fat and lipoid phosphorus, thus determining inorganic phosphorus on the same sample and rendering unnecessary the tedious and, in the case of fresh brain and blood, the somewhat unsatisfactory and difficult method of hot mater extraction. It is the hope of the author t h a t some of these points will be more thoroughly investigated. The author wishes to express thanks t o Dr. E. B. Forbes for his courtesy in making this investigation possible. I~TJTRITIOS LABOKATORY, O H I O AGRICVLTUR.4L
\T*OOSTER,
EXPERIMENT STATION, OHIO.
LABORATORY AND PLANT DESIGN AND EQUIPMENT O F THE CHEMICAL ENGINEERING LABORATORY AT THE UNIVERSITY O F WASHINGTON. R y H. K. B E N S O N .
Received April 3, 1912.
A description of the new chemistry building of the University of Washington was published some time . S o c . , 32, 9 6 7 ) . Recently the space ago ( J . - 4 ~Chew. set aside for chemical engineering practice has been
utilized in the design and equipment of a chemical engineering laboratory of which a brief description may be of interest. The general plan is shown in the accompanying diagram (Plate I ) . The room is well lighted and completely fire-proof, since i t has a concrete floor, brick walls. and wire-lath-cement ceiling. It is supplied with all the accessory equipment available in the building such as steam, gas,_compressed air, etc., and
