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suction may be entirely omitted. I n this event, howerer, the air agitation must be accomplished by air pressure instead of air leakage. Fortunately, the odor of nitrobenzene is so strong that it indicates the presence of minute quantities. The absence of the characteristic odor in the wax is evidence that practically all the nitrobenzene has been removed. Results Typical results obtained on slack waxes are given in Table I. Table I SLACK WAX
YIELD
P e r cent 45.3 45.9 46.8
MELTING POINT
F.
O
c.
123.5 122.0 122.8
50.8 50.0 50.4
2
39.7 36.7
123.9 124.0
51.1 51.1
3
56.2 56.5
124.0 123.4
51.1 50.8
~
These yields check satisfactorily with those obtained in the plant sweating ovens. It is difficult to prepare a “known” slack wax. This was attempted, however, by mixing a finished wax with a sweat oil in known proportions. The results on this synthetic slack wax indicated that practically all the wax is recovered by the nitrobenzene method.
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Discussion Acetone did not prove to be so useful a solvent in this type of apparatus as nitrobenzene. The advantages of using nitrobenzene are evident from the following considerations. The wax obtained by means of nitrobenzene is compact and seems to retain very little of the solvent, while the wax separates from acetone in a flocculent state and tends to retain appreciable amounts of acetone. Inasmuch as the specific gravity of nitrobenzene is greater than that of the wax, the latter collects as a cake on the surface of the oil-nitrobenzene solution. I n the apparatus used, this cake forms just above the narrow portion of the flask with the clear oil in the constricted part, whence i t may be removed without loss of wax. Most of the wax clings to the side of the flask and does not fall down when the oil solution is drawn off. I n the case of acetone i t is impossible to separate the oil solution from the wax sharply by merely drawing off the supernatant liquor, because the wax is flocculent, very slow in settling, and does not form a compact layer. Attempts at filtration were not satisfactory. The greater solubility of the oil in nitrobenzene is advantageous in that smaller quantities are required for a given amount of the sample. Nitrobenzene is also preferable because its complete removal from the wax is quite definitely assured when the wax is free from all odor of nitrobenzene. Acknowledgment The authors are indebted to W. H. J. Xanthorpe for his assistance in the laboratory.
Detection and Determination of Nitrogen-Bearing Chemicals Added to Animal or Vegetable Nitrogenous Materials’ By H. C. Moore and Robert White ARMOUR FERTILIZER WORKS, CFIICAGO, ILL.
H E practice of adding such chemical forms of nitrogen as sulfate of ammonia and cyanamide to so-called nitrogenous tankage by unscrupulous manufacturers has reached the point where attention should be called to it. Since these chemicals can be bought as such for from $1.00 to $1.50 per unit less than the organic form in the tankage, the effect of this practice is obvious. The writers have found sulfate of ammonia in numerous lots of nitrogenous tankage, sometimes cyanamide, and sometimes both of these materials. Nitrate of soda or Leunasalpeter might also be present, although it would be of doubtful profit to the manufacturer, on account of the cost of the nitrate form of nitrogen, and because the usual method of determining the nitrogen present in organic materials is not so applied as to include the nitrate form. Urea, which is now comparatively cheap in Europe, might be added to foreign nitrogenous tankage for import to this country, and thus escape duty. It is not difficult to detect the presence of these various chemical forms of nitrogen, but until recently it has been difficult to determine accurately the quantities, especially
T
1 Presented before the Division of Fertilizer Chemistry a t the 72nd Meeting of the American Chemichl Society, Philadelphia, Pa , September 5 to 11, 1926.
when several are present in the same mixture. The methods of analysis given herein are not all new, but their application in the detection of the practice mentioned above may not be so well known. Mechanical Separation of Cyanamide and S u l f a t e of Ammonia The silver nitrate test for cyanamide usually fails to show this material when present in tankagc. But if some of the sample is mixed with an excess of carbon tetrachloride, a mechanical separation (due to gravi3,y) is made, when the heavy particles, including cyanamid(:, sulfate of ammonia, etc., will settle to the bottom of the container, while the tankage will float. If the portion which settles is tested with silver nitrate, cyanamide is easily detected. This mechanical test may conveniently be applied as follows: PIace 30 to 40 grams of the tankage, preferably ground to pass a 10-mesh sieve, in a beaker or casserrle and add about 200 cc. of carbon tetrachloride and stir. Afte allowing to settle a short time, the lighter floating material, aloug with most of the carbon tetrachloride, is transferred to another container and the heavier portion tested for sulfate of ammoria, cyanamide, etc. If the carbon tetrachloride-tankage mixture is mixed with a n approximately equal volume of turpentine, crystals of urea, if present, will appear floating or in partial suslmxion.
February, 1927
I,VDUSTRIAL A N D ENGINEERING CHEMISTRY Qualitative Tests
Mix about 5 grams of the sample with about 150 cc. of water in a beaker and, after allowing to stand for a few minutes, pour through a filter, testing as follows: NITRATES-Transfer about 1 cc. of the filtrate t o a small test tube, add an equal volume of concentrated sulfuric acid, mix, and cool. Add carefully a cold, concentrated solution of ferrous sulfate, allowing the latter to run down the side of the tube so t h a t the solution will float on top of the heavier liquid. If nitrates are present, a brown ring will form a t the junction of the two liquids. CYANAMIDE-Take a small portion of t h a t part of the sample which settled out when mixed with carbon tetrachloride and, after drying to remove any carbon tetrachloride, stir up with water and filter. To a portion of this filtrate add 10 cc. of 5 per cent silver nitrate solution. A yellow or brownish yellow precipitate indicates cyanamide. This precipitate is insoluble in ammonia, but soluble in nitric acid. There is a little difficulty, however, in detecting cyanamide, as t h e characteristic odor is easily noted on adding water to t h a t portion which settles from carbon tetrachloride. SULFATE OF AMMONIA-The needle-like crystals of sulfate of ammonia are usually detected by the naked eye or with the aid of a magnifying glass. Its presence can be confirmed by testing a portion of the filtrate above, adding a few drops of caustic soda, and warming slightly. Ammonia fumes will indicate the presence of ammonia salts. Another portion of the filtrate can be tested with barium chloride. A precipitate of barium sulfate will be formed if sulfates are present. UREA-TeSt a portion of the filtrate by adding a few drops of bromine water and the caustic soda solution. If urea is present, the solution will effervesce, liberating nitrogen gas. Urea melts at about 132” C. losing ammonia and forming biuret, which when treated with a solution of caustic soda containing a trace of copper sulfate produces a reddish violet solution. Quantitative Determination
265
KITROGENIN FORM OF CYANAMIDE-TOa 50-cc. aliquot of solution 3 add excess of 5 per cent silver nitrate solution, and finally 20 cc. of 10 per cent potassium hydroxide solution. Filter and wash the brown precipitate, and determine nitrogen in the residue by the Kjeldahl method, substituting 1 gram of copper sulfate in place of mercury. (Modified Car0 method.3) This method includes nitrogen present as cyanamide, also t h a t as dicyandiamide. NITROGEN AS AMMONIUM SULFATE OR AMMONIA SALTS-TranSfer a 50-cc. aliquot from solution 2 to a Kjeldahl flask, add 150 cc. of water and excess of magnesium oxide, and distil. The ammonia thus collected indicates t h a t present in the form of ammonia salts, usually referred t o as free ammonia. If urea is not present, solution 3 may be used, but extraction with alcohol will remove small amounts of urea usually present in organic materials. NITROGENAS UREA-TranSfer 50 cc. of the alcoholic solution 1 into a 500- to 600-cc. Kjeldahl flask, add 50 cc. of water, boil t o remove alcohol, concentrating to 40 or 50 cc., add 100 CC. of water, and cool. Add 0.25 gram urease, connect flask to condenser, and allow to remain cool for half a n hour, with frequent shaking. Finally add about 1 gram of paraffin, 5 grams of heavy magnesium oxide, and distil until about 100 cc. have been collected. The nitrogen present in the urea is converted by the urease quantitatively to the form of ammonia, which is distilled and collected as above in excess standard acid. Note-Ammonium nitrate is slightly soluble in -alcohol. If this material is present, the above procedure should be slightly modified a s follows: Transfer 50 CC. of solution 1 into a 500- t o 600-cc. Kjeldahl Bask, add 7 5 CC. of nearly absolute alcohol, add magnesium oxide, and distil about 75 cc., collecting in standard acid. The ammonia thus collected would otherwise be determined a s urea ammonia in t h e above procedure. This ammonia recovered should be added to the free ammonia a s determined in solution 2 .
Accuracy of M e t h o d
I n order to prove the reliability of this procedure it was applied to a mixture of known ammonia content as follows: KNOWN AMMONIA CONTENT Per cent
AMMONIA FOUND Per ccn
Solution 1. Transfer 5 grams of the ground tankage to a Cyanamide (80 Ibs.) 1.04 Cyanamide, including dicybeaker, add about 100 cc. grain or denatured alcohol (formula andiamide 1.15 No, 30) redistilled over caustic soda until practically anhydrous. Sulfate of ammonia (80 Ibs.) 1.00 Sulfate of ammonia or ammonia salts 1,15 Allow t o stand half a n hour, stirring frequently. Transfer from 1.00 Nitrate of soda (110 lbs.) 1.02 Nitrate beaker t o a filter and wash with alcohol, finally making volume Urea (40 Ibs.) 1.06 1.10 Urea Nitrogenous tankage (16901bs.) 7 . 9 0 to 250 cc. Solution 2. Wash the residue on the paper from solution 1 TOTAL 12.06 into a 250-cc. volumetric flask with about 150 cc. of water, shake frequently for 15 minutes t o a half hour, finally making t o From the results it will be noted that the ammonia in volume. Pass through a dry filter and use for determining am- the various forms is determined with sufficient accuracy moniacal nitrogen. Solution 3. Transfer 5 grams of the sample into a 250-cc. for most purposes. When the free ammonia was determined by distillation volumetric flask, add about 200 cc. of water, stopper, and shake frequently for one hour. Make t o volume, pass through dry with magnesium oxide, and without removing urea, 1.46 filter. This solution is used for determining cyanamide and per cent ammonia was found. It is thus apparent that nitrate nitrogen. NITROGENIN FORM O F NITRATE-TranSfer two 5o-CC. por- when urea is present it is necessary to remove it with alcohol tions of solution 3 to separate Kjeldahl flasks. To aliquot in order to determine the free ammonia accurately, as from A add 10 to 12 perforated glass beads (3 t o 5 rnm.), 2 grams of 5 to 10 per cent of the ammonia in urea will be driven over reduced iron, and 10 cc. of dilute sulfuric acid (1 : 1). Rotate by boiling with magnesium oxide and water. slowly and when any violence of reaction has moderated, place The nitrogenous tankage used in this mixture, when dison hot plate and boil gently for 5 minutes. Remove, add 40 cc. of water, and cool. Add 100 cc. of 42” Bil. caustic soda tilled with magnesium oxide alone, showed 0.21 per cent solution, connect at once with a n upright condenser by means free ammonia. of suitable connecting bulb, and boil until 150 to 160 cc. have disThe modified Caro method for determining cyanamide tilled over, and the distillate as i t drops from the condenser ammonia gives slightly high results. A sample of comtube is neutral to litmus paper. Collect the ammonia in a mercial cyanamide alone tested a t the same time yielded measured quantity of standard acid, titrating the excess with only about 90 per cent of its total ammonia by this method. standard alkali and determine the ammonia thus collected. The ammonia so obtained represents t h a t obtained from niIt is advisable, when cyanamide is present, to make up a trates, ammonia salts, and other forms of nitrogen which are mixture of known analysis to run along as a check. converted into ammonia by this treatment. To aliquot B is likewise added the perforated glass beads and P r o t e c t i o n of Buyer 10 cc. sulfuric acid (1 : 1). Boil as before, add 40 cc. of water, and cool, finally adding 100 cc. of 42” Bil. caustic soda and disAs a protection in purchasing nitrogenous tankage as tilling as above. The difference between the ammonia obtained well as other forms of organic ammonia, a clause might be by A and B is t h a t in the form of nitrate. (method of C. H. Jones.*) inserted in the contract somewhat as follows: “Material Caufion-If distillates A and B fail to show neutral to litmus after distilling the proper amount, repeat t h e test, using 25-cc. aliquots, in which case 25 cc. of water should he added previous t o t h e addition of t h e 10 cc. sulfuric acid. It is important t h a t the distillation of A and B he conducted synchronously. ~
9 Paper presented before the meeting o f t h e Association of O5cial Agricultural Chemists, Washington, D. C., October 18 to 20, 1928.
guaranteed to be free from all inorganic ammoniates, such as sulfate of ammonia, nitrate of soda, etc., also free from cyanamide and urea.” Some manufacturers object to this clause and prefer to state that the material is “free from admixtures of all inorganic ammoniatesJJJetc. This 8
Pranke, “Cyanamid Manufacture, Chemistry and Uses,” p 21
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266
is hardly satisfactory, as it rests with the buyer to prove that the seller has actually added the materials in question, whereas their presence in quantity is sufficient to convince the buyer that they have been deliberately added. Reputable manufacturers of nitrogenous tankage free from admixtures will not object to such a clause. Free Ammonia Not Formed during Manufacture
Manufacturers of nitrogenous tankage frequently claim that the free ammonia found in their product has been formed during manufacture, as a result of adding small quantities of sulfuric acid to the various materials, such as leather scrap and other waste products. and digesting with live
T'ol. 19, No. 2
steam under pressure. The writers' experience in the manufacture of nitrogenous tankage, however, has shown that sulfate of ammonia or ammonia salts will not be found in the finished product, except in fractional per cents. Sulfuric acid has been added in such amounts as to increase considerably the water-soluble nitrogen, without materially increasing the free ammonia content. Whenever free ammonia is found in organic materials, such as nitrogenous tankage, much in excess of 0.5 per cent, one may have reason to be suspicious that sulfate of ammonia or ammonia salts has been added. The free ammonia content of various organic materials of good quality will average 0.2 to 0.3 per cent, varying from about 0.10 to 0.60 per cent.
American Tung Tree Culture' By Henry A. Gardner INSTITUTE OF P A I N T AND V A R N I S H RESEARCH,
HREE years ago at the annual convention of the paint and varnish industry, the project of developing an American tung oil industry was brought to a definite head. At that time considerable difficulty was experienced with some of the shipments obtained from China. Skilfully adulterated oil and a nervous market were factors which strengthened the desire of the American paint and varnish industry to start the production of tung oil in America. 4 s a result, 300 acres of land in the vicinity of Gainesville, Fla., were acquired, cleared, and planted before four months had elapsed. At the same time nurseries were established for the production of seedlings for distribution to other planters. The object of planting 300 acres was to demonstrate to Florida farmers the possibilities of such a crop and give them a visual demonstration of the rapidity with which the trees could be grown in America. As a result, one organization soon afterward acquired about 2400 acres of land
T
WASHINGTON. D. C.
and seed have been supplied to about two hundred individuals in Alabama, Cuba, Florida, Georgia, Louisiana, Mississippi, South Carolina, Texas, the Philippine Islands, and Hawaii. The plan was to get a wide distribution of these seedlings in regions affording climates in which the trees would probably grow successfully. Although it is true that the majority of the plantings have consisted of small numbers of trees (30 or more), many of them range up to 5000 trees. I n the vicinity of Gainesville, however, i t is estimated that there are now planted about 300,000 trees. most of which are from one to two years old. These trees, though very young, have reached heights of 7.5 to 10 feet, and some are bearing a substantial crop of seed. It is expected that by the end of 1927 an oil-crushing mill will be erected a t Gainesville to take care of that year's crop and to act as a community crushing plant for the seed that may later be obtained from the crops grown by neighboring farmers. Results to date also indicate that many of the idle sugar lands in Louisiana and Cuba are ideal for the planting of tung-oil trees, and that similar possibilities exist in Hawaii and the Philippines. It is expected that American tung oil of extremely light color and known purity will begin coming into the market in small quantities before 1928, to supplement the uncertain supply of imported oil. The indicated production of tung oil, based on individual producing trees in Florida, may possibly range from 400 to 1800 pounds of oil per acre) starting from the third to the ninth year. The trees are hardy and apparently hare An average producing age of from tmentyfive to thirty years, probably longer if given proper attention. MAXIMUM OIL YIELDSOF
near Gainesville, and by the spring of 1926 twelve h acres of this land were also planted in tung trees, the seedlings being furnished from the original nurseries mentioned above. From these same nurseries and from nurseries established by the Florida Experiment Station, seedlings 1
Received September 7, 1926.
,
CROPS Pouwds oil p t r acre . . , . , . . . . . . 1.50
\'ARIOKS
.
Cottonseed.. , , . . , . . , , , . . , . Peanuts ................................ 300 Flaxseed , . . . , , , , , , , , . , , , , , , , . , . . . . . . . . 255 T u n g trees (9 years old) (possible y i e l d ) . . . 1800a ~~~
Hd
This theoretical estimate is based on a yield of 30 pounds of oil per tree from selected trees in Florida.
