June, 1923
1ND USTRIAL AND ENGINEERING CHEJfISTRY DISCUSSION
A large amount of investigation has been done along soilacidity lines, and it would seem that the time is ripe for more definite expressions in describing soil conditions than have been commonly applied in the past. The term “neutral” as applied to soil should include to what indicator it is neutral or what p H it has-as neutral to methyl red would leave ferrous iron and manganese and sometimes aluminium in soil solution. “Thoroughly limed” is another term frequently used, and the reader asks, “Thoroughly limed to accomplish what?”-as the limestone required to precipitate ferric iron and aluminium at p H 5.5 will usually be all that is required, unless manganese is present, and there is no use in adding two tons to precipitate the manganese when four or five tons are required to do it. This condition may be determined by the potassium thiocyanate method for soil acidity. It would seem, from the data gathered by numerous investigators, that the most desirable reaction of the soil for
637
most crops ranges between p H 5.5 and 6.5. In view of this fact it would not seem feasible to add limestone enough to precipitate the manganese as a hydrate, not only because of the expense involved, but also because the soil reaction is changed from its most productive phase, owing possibly to iron being thrown out of solution and aluminium coming back into solution, as shown by the graph. No suggestions are offered as to best treatment for the manganese soils described to make them productive, except that it was noted that some of these responded best to applications of manure. This may have been due to the organic matter changing the form in which manganese was present. It is not the intention of the writers to convey the idea that all nonproductive soils are due to the presence of these elements in excess, as this is not the case, but it is believed that manganese is the chief cause of toxicity in some soils and aluminium in other soils, and that the potassium thiocyanate method for soil acidity is useful in detecting soil trouble from these sources.
Qualitative Scheme for Detection of Cyanamide and Related Corn poun ds‘ By G. H. Buchanan AMERICANCYANAMID Co., 611 FIFTH AvE., N E W YORK,N. Y.
I
In the experimental laboratory of the American Cyanamid are closely related to cyanT HAS been said of cyanamide that, like benCompany the examination of nitrogenous mixtures is a matter amide in a structural or of daily routine, and a standardized procedure which is applicable generical sense, but rather ~ 0 1and ethyl alcohol, it is a fundamental raw to the mixtures most commonly encountered has been deoised. This because of their commerprocedure, worked out in a form similar to that used in ordinary cial relationship. In alphamaterial of organic chemistry. The justice of the qualitative schemes of inorganic chemistry and suficiently explicit betical sequence, the ten to be followed by anyone familiar with their technic, has proved SO forms, which are the ones characterization will be useful that we feel warranted in making it public. most commonly encoungranted when it is recalled that cyanamideis the starttered in the work of this ing material for the comlaboratory, are as follows: merciitl production of such important compounds as urea, Ammonia and its sa,ts Guanylurea and its salts thiourea, dicyandiamide, and guanidine, and that these are Cyanamide Nitric acid and its salts Hydrocyanic acid and its salts Thiocyanic acid and its salts intermediates for a host of other organic compounds. MoreThiourea over, the place of cyanamide in the preparation of the inor~ f its salts ~ ~ ~ ~ Urea ganic compounds of nitrogen is well established-ammonia, nitric acid, and their salts are produced from it, and the It is assumed that the mixtures under examination contain development in this country of a highly successful process no nitrogenous compounds other than those listed. Profor its transformation into cyanide is one of the distinctive vision is made for the interference of the inorganic radicals achievements of recent chemical technology. most commonly found in commercial mixtures. The scheme This increase in the technical applications of cyanamide has consists essentially of three parts. PRELIMINARY TESTSFOR THE MOST COMMONINTERbeen remarkably rapid, so that the analytical chemist may be called upon a t any time to examine a mixture which either FERING RADICALS-sulfide, although rarely present in large contains cyanamide or has been prepared from it. When he amount, is a common constituent of commercial mixtures, attempts to inform himself concerning the analytical char- and must be completely removed on account of its interacteristics of this group of nitrogenous compounds he is more ference in all the tests in which silver nitrate is used. Phosthan likely to meet with difficulty, either because he may not phate, a common ingredient of the mixtures to which this qualifind in the published literature methods of testing which are tative scheme is most often applied, must also be removed. applicable to the commercial mixtures under examination, or PREPARATION OF SOLUTION FOR AxALYsIs-The sulfides because he may be in doubt as to the behavior of nitrogenous and phosphates are removed and a solution suitable for the forms other than those for which the tests have been specif- application of the subsequent tests is obtained. Since it ically chosen. is impossible to draw the analytical directions so closely as to cover all possible contingencies, many details are left to the THESCHEME The scheme here given provides for the identification of judgment Of the lDENTIFICAT1oN OF NITRoGENoUs FoRMS-TestS and ten nitrogenous forms when present in practically any combination. These forms were selected, not because they all comments as seem necessary for their intelligent application are given. The formal procedures are confined to the 1 Presented before the Division of Fertilizer Chemistry a t the 64th analytical operations, and remarks being given Meeting of the American Chemical Society, Pittsburgh, P a , September 4 in the notes. to 8, 1922.
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INDUSTRIAL A N D ENGINEERING CHEMISTRY PRELIMINARY TESTS
SULFIDESULFUR-Shake a small portion of the material with water, filter if necessary, and add to the clear filtrate a little lead carbonate which has previously been ground to a pulp with water. Shake for 1 min. (Blackening of the lead carbonate, presence of inorganic sulJide sulfur.) NOTE-Inorganic sulfide sulfur is usually present in compounds prepared from commercial calcium cyanamide. It interferes with many of the subsequent tests and provision for its removal is made in a later paragraph.
PHosPHATE-l?ilter the lead carbonate mixture obtained in the test for sulfide sulfur, make the clear filtrate acid with nitric acid, add a little solid ammonium nitrate, heat to 60°, and add a few cubic centimeters of ammonium molybdate solution. (Yellow precipitate, presence of phosphate.) Nom-This qualitative scheme is intended for use particularly in the examination of fertilizer mixtures in which watersoluble phosphate is an important constituent. Provision for the removal of this interfering radical is made in a later paragraph.
PREPARATION OF SOLUTION
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thiocyanic acids. Ammelin and melanurenic acid, two of the less common cyanamide decomposition products, which are practically insoluble in cold water, are also eliminated a t this point.
IDENTIFICATION OF NITROGENOUS FORMS TEST 1. AMMONIACAL SILVERNITRATE-TO a 10-cc. portion of the solution add 1 CC. of strong ammonia and 1 cc. of 10 per cent silver nitrate. Shake for 1 min. (Bright yellow precipitate,. presence of cyanamide. Black precipitate, presence of thiourea.) NOTES-( 1) Thiourea is desulfurized by ammoniacal silver nitrate and a precipitate of silver sulfide and silver cyanamide is produced. Silver cyanamide is bright canary-yellow. If the precipitate is brown or black, thiourea is present, provided, of course, that the inorganic sulfides were completely removed during the preparation of the solution. If thiourea is present, pass on to Test 2; if absent, omit Test 2 and pass on to Test 3. (2) Th,e volume of the precipitating reagent recommended in this and in the subsequent tests is the quantity necessary to ensure detection of the nitrogenous constituent when present in small amounts. With larger amounts, larger quantities of reagent may be required for complete precipitation. Where a separation is to be made, the analyst is expected to test for complete precipitation. (3) When large quantities of cyanide or thiocyanate are present, 1 cc. of strong ammonia may be insufficient to keep their silver salts in solution, but, since these salts are white, their precipitation will not prevent the detection of either cyanamide or thiourea. The ammonia addition should not be increased, as this would lessen the delicacy of the cyanamide test. (4).Guanylthiourea, a less common form, would be identified as thiourea by this test.
ABSENCEOF PHosPHATE-If the material is completely soluble and if sulfide sulfur is absent, dissolve 5 g. of the material in about 150 cc. of cold water. If it is not completely soluble, or if inorganic sulfides are present, grind 5 g. in a small mortar with 50 cc. of cold water, add sufficient caustic soda to make the reaction alkaline or neutral to litmus, if it is not already so, and then add 2 g. of lead carbonate previously TEST2. CYANAMIDE I N PRESENCE OF THIOUREA-TO a ground to a pulp with water. Shake the mixture for several minutes, filter, and wash to a volume of about 150 cc. In 10-cc. portion of the solution add 1 cc. of saturated lead either case make the resulting solution neutral to litmus, acetate solution and then 1 cc. of strong ammonia. Shake adding dilute caustic soda or dilute sulfuric acid as required. for 1 min. (Yellow precipitate, presence of cyanamide; Filter off and reject any precipitate that may be formed, white precipitate, absence of cyanamide.) Dilute the solution to a volume of 250 cc., mix thoroughly, NOTES-( 1) Ammoniacal lead acetate does not desulfurize thiourea. Lead cyanamide is similar in appearance t o silver and keep in a cool place. PRESENCE OF PHOSPHATE-weigh a 10-g. sample into a cyanamide, but the full yellow color develops more slowly. When very small amounts of cyanamide are present several mortar, add about 50 cc. of water and then sufficient milk of minutes may be required for the appearance of the yellow. lime to completely precipitate the phosphates, and grind with (?) Tests 1 and 2 are given precedence because of the position a pestle. Pour the mixture into a 250-cc. flask and add lead of importance naturally belonging t o cyanamide as the parent carbonate as directed in the preceding paragraph. If sul- substance of the group, and because, on account of its instability, mixtures containing cyanamide must be handled with special fides are present, dilute to 250 cc., and shake thoroughly. precautions. In the absence of cyanamide, many of the subPour the mixture through a dry filter and test for complete re- sequent tests are simplified. moval of phosphate. Neutralize 125 cc. of the filtrate to litTEST3. ACIDSILVERNITRATE-TO a 10-cc. portion of the mus with dilute sulfuric acid, filter if necessary, and dilute to solution add 3 drops of concentrated nitric acid and 1 cc. of 250 cc. 10 per cent silver nitrate. Shake for 1 min. and, if no preNoTEs-(~) A weighed sample is used to permit a rough es- cipitate forms, cool in an ice bath, and let stand for 30 min., timation of the amounts of the various nitrogenous forms present. To facilitate this estimation, preference has been given to tests with occasional shaking. (White precipitate, pFesence of which produce a precipitate, and color tests have been avoided compounds of Group 1 or of a chloride. No precipitate, abwherever possible. In the examination of mixtures known to be sence of compounds of Group 1.)
low in nitrogenous constituents-as, for example many commercial fertilizer mixtures-a larger sample may be handled. In the examination of salts a 1-g. sample will be sufficient. All of the tests will detect 0.5 mg. of nitrogen per cc. of solution and nearly all will detect 0.2 mg. per cc. (2). The extraction must be made with cold water and the solution must be kept cold to prevent change of the nitrogenous forms, particularly the cyanamide. For the same reason, all tests should be made on the day the solution is prepared. (3) The final solution is made neutral to litmus because cyanamide solutions are most stable under such conditions. The neutralization should be made to litmus paper and not by use of solutions of indicator added t o the solution under examination, because the presence of the indicator would i n t e r h e in subsequent tests. (4) Grinding with milk of lime may cause some loss of ammonia when considerable amounts of ammonium salts are present, but the loss will not be large enough to involve danger of failure to detect the ammonia a t the proper point in the analytical scheme. (5) It is assumed that all the nitrogenous forms are soluble in water. The scheme does not provide for insoluble forms, such as the metallic salts of cyanamide or of hydrocyanic and
GROUP1 PRECIPITATED BY ACIDSILVER NITRATE Cyanide Dicyandiamide Thiocyanate Thiourea
GROUP2 NOTPRECIPITATED BY ACIDSILVER NITRATE Ammonia Cyanamide Guanidine Guanylurea Nitrate Urea
NoTEs-(~) If acid silver nitrate yields no precipitate, all compounds of Group 1 are absent. Omit Tests 4, 5, 6, and 7, and pass on t o Test 8. I f a precipitate is obtained, one or more of the compounds of Group 1 may be present, or the precipitate may be that of a halogen. The members of Group 1 are now identified by the following tests: Thiocyanate, by Test 4; cyanide, by Test 5 ; and dicyandiamide, by Tests 6 and 7. Thiourea, the fourth member of this group, has already been identified in Test 1. (2) Silver cyanide and thiocyanate are very insoluble in dilute nitric acid and are precipitated rapidly and completely. Silver dicyandiamide, even when present in considerable amounts,
June, 1923
INDUSTRIAL A N D ENGINEERING CHEMISTRY
usually forms slowly, separating in voluminous semitransparent flocks or frequently in long needle crystals. Its appearance is characteristic and, once seen, it is easily recognized. It is much more soluble in warm than in cold solutions, and thorough chilling, as in an ice and salt bath, may be necessary to produce the precipitate when the dicyandiarnide is present in small amounl s. (3) Since commercial materials usually contain sufficient chloride to yield a precipitate a t this point, a positive result has little significance so far as identification of the nitrogenous forms is concerned. If the test is negative, however, the examination is materially simplified.
TEST4. THIOCYANATE-TO a 10-cc. portion of the solution add 2 drops of concentrated hydrochloric acid and then 5 drops of 10 per cent ferric chloride solution. (Red coloration, presence of thiocyanate.) TEST5. CYAXIDE-TOa 10-cc. portion of the original solution add 1 cc. of 10 per cent caustic soda and 5 drops of a saturated'solution of ferrous ammonium sulfate. Heat for a few minutes and then add 2 drops of 10 per cent ferric chloride solution, followed by dilute hydrochloric acid, drop by drop, until the hydroxides of iron are completely dissolved. Pour the mixture through a small filter and wash with water. (Blue precipitate, presence of cyanide.) TEST6. DICYANDIAMIDE I N ABSENCEO F THIOUREA-Repeat Test 3. If a precipitate forms as soon as the silver nitrate is added, allow to settle and then add more silver nitratc:, drop by drop, until no further precipitate is formed. Heat the mixture to 60" C. on a water bath and then filter. Add 5 drops of the silver solution and cool in an ice bath, with occasional shaking, allowing the mixture to stand for at least 30 min. (White precipitate, which separates on cooling the solution, presence of dicyandiamide.) NoTEs-(l) The silver compound of dicyandiamide is much more soluble in warm than in cold water, and an approximate separation may be made from cyanide, thiocyanate, and chloride, whose silver salts are insoluble in both hot and cold solutions. It is, of course, essential that the solution contain enough silver to combine with all the members of the group. The addition of the 5 drops of silver to the filtrate before cooling is made to test for the presence of sufficient silver; no precipitate should result until the solution has been cooled. See Note 2 under Test 3 for remarks on the appearance of silver dicyandiamide. ( 2 ) The temperature of the mixture should be raised to GO ' C. without delay and the heating should not be prolonged, since dicyandiamide may be converted to guanylurea by the action of the nitric acid. (3) This test can be applied in presence of thiourea only after removal of the thiourea, as described in Test 7. I N PRESENCE O F THIOURE-4-TO TEBT7. DICYANDIAMIDE a 10-oc. portion of the solution add 3 cc. of strong ammonia and 3 cc. of 10 per cent silver nitrate. Shake until the precipitate is coagulated and then add silver nitrate, drop by drop, until no further precipitate forms. Filter o f f the black precipitate and add to the clear filtrate 5 drops of silver solution as a test for complete precipitation. If no permanent precipitate is produced by this last silver addition, add nitric acid, drop by drop, until the solution is just acid, and then 5 drops in excess, keeping the mixture cold during the addition. If no precipitate forms a t once, cool for 30 min. in an ice bath, with frequent stirring. (Xo precipitate, absence of dicyandiamide.) If a precipitate is obtained, add silver nitrate, drop by drop, until no further precipitate is formed, heat to 60" C., and proceed as in Test 6.
EorES-(l) Ammoniacal silver precipitates silver sulfide from thiourea, leaving cyanamide in solution if insufficient silver is used, or precipitating it if an excess of silver is present. After filtering off the precipitate obtained with ammoniacal silver, the solution is in proper condition for the application of Test 8. (2) The minimum amount of silver solution for complete precipitation is recommended in order to avoid unnecessary dilution. The solution must be kept cold during the addition of the nitric acid, to prevent decomposition of the dicyandiamide.
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TEST8. PICRIC ACID-TO a 10-cc. portion of the solution add 1 cc. of alcoholic picric acid and stir for 5 min., using a stirring rod and scratching the sides of the container. (Yellow precipitate, presence of guanylurea or guanidine.) NoTEs-(~) If Test 8 is negative both guanylurea and guanidine are absent. Omit Tests 9 and 10 and pass on to Test 11. If Test 8 is positive, guanylurea or guanidine, or a mixture of the two, may be present. Proceed to Tests 9 and 10. (2) The alcoholic picric acid solution is prepared by dissolving G g. of picric acid in 100 cc. of 95 per cent alcohol. (3) Guanylurea picrate is bright yellow and guanidine picrate is orange-yellow, but the difference is not sufficiently pronounced to be of value in identification. The analyst should familiarize himself with the appearance of these compounds before applying the test, since precipitates other than the picrates of guanylurea and guanidine may sometimes be obtained. Thus, picric acid itself may be precipitated from concentrated salt solutions, particularly if the solutions are cold. The addition of alcohol may produce a precipitate. In case of doubt as to the nature of the precipitate, a blank test should be made with 1 cc. of alcohol alone. (4) It is assumed that the solutions under examination contain no nitrogenous compounds other than the ten listed. With care, however, the scheme may be applied to the analysis of fertilizer mixtures containing ammoniated base or similar products of the acid hydrolysis of proteins. Since ammoniated base usually gives a flocculent precipitate with picric acid, it is necessary to defecate the solution with basic lead acetate before applying the test. Mixtures containing cottonseed meal also sometimes give a gelatinous precipitate with picric acid. This may be eliminated by treatment with basic lead acetate. Guanylurea and guanidine are not removed by basic lead acetate. In general, then, if the precipitate in Test 8 is gelatinous or flocculent and if a commercial fertilizer mixture is under examination, repeat the test on a fresh portion of the solution after defecation with basic lead acetate. (5) Several of the less common decomposition products of cyanamide, notably melamine, biguanide, and guanylthiourea, are also precipitated by picric acid. Melamine yields a picrate of very characteristic appearance-canary-yellow, felted needles, which may be recrystallized from hot water.
TEST9. KICKELTESTFOR GUANYLUREA-TO a 25-cc. portion of the solution add 5 cc. of nickel reagent and then 10 cc. of 10 per cent sodium hydroxide solution. Let stand in an ice bath for 1 hr., scratching the sides of the container occasionally with a glass rod. Pour through a small filter and wash once with water, keeping filtrate and washings separate. (Orange crystalline precipitate, presence of guanylurea.) Use the filtrate for Test 10. Reject the washings. NoTEs-(~) Guanidine yields no precipitate with nickel. If Test 9 is positive, pass on to Test 10. If negative, the positive result obtained in Test 8 is considered sufficient for the identification of guanidine. (2) The nickel reagent is made up as follows: Dissolve 10 g. of nickel sulfate and 30 g. of citric acid in 150 cc. of water and add 50 cc. of strong ammonia. (3) This test depends upon the formation of crystalline nickel guanylurea in alkaline solution. When considerable quantities of guanylurea are present the formation of the crystalline precipitate is preceded by a color change from blue to yellow, which occurs as soon as the caustic soda is added. This color change is not to be confused with the blue-green color change which always occurs when caustic solution is added to the nickel reagent. (4) The crystalline precipitate of nickel guanylurea forms slowly and the test should not be considered negative until the mixture has stood for a t least an hour, preferably longer. A flocculent precipitate which sometimes develops on long standing must not be confused with the characteristic orange crystals of nickel guanylurea. ( 5 ) Of the less common decomposition products of cyanamide, biguanide also yields an insoluble nickel compound.
TEST10. GUANIDINE I N PRESENCE OF GUANYLUREA-TO the filtrate from Test 9 add concentrated hydrochloric acid, drop by drop, until it is just acid to litmus, and then add 1 or 2 drops of ammonia and 2 cc. of alcoholic picric acid. Cool in an ice bath, with occasional stirring. (Yellow crystalline precipitate, presence of guanidine.)
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INDUSTRIAL A N D ENGINEERING CHEiMIXTRY
NOTE-It is, of course, essential that enough nickel reagent t o completely precipitate the guanylurea be used and that sufficient time for complete precipitation be allowed. The filtrate from the nickel guanylurea should have a green color, showing the presence of an excess of nickel. If it does not have a gi-een color, add 5 cc. of the nickel reagent and allow to stand.
TEST11. AMMONIA I N ABSENCEOF CYANAMIDE-TOa 10-cc. portion of the solution add 1 g. of magnesium oxide which has been ground to a pulp with water, and heat to boiling. Identify ammonia by its odor or by use of litmus paper. NOTE-Under these conditions none of the ten nitrogenous forms, except ammonium salts and cyanamide, yield appreciable quantities of ammonia. If cyanamide is present it must be removed, as recommended in Test 12. If the findings of Test 11 are uncertain, repeat it as follows: Dilute a 50-cc. portion of the solution with 100 cc. of water, add 2 g. of magnesium oxide ground to a pulp, and boil the mixture in an ammonia distilling apparatus for just 15 min., absorbing the distillate in water. Add 2 drops of methyl red indicator and titrate the liberated ammonia with 0.1 N sulfuric acid. I N PRESEKCE OF CYANAMIDE-TOa TEST12. AMMONIA 25-cc. portion of the solution add 5 cc. of 10 per cent silver nitrate and then 5 cc. of 10 per cent caustic soda. Shake to coagulate the precipitate, filter, and wash twice with cold water. Add to the filtrate 5 g. of magnesium sulfate dissolved in a little water, dilute to about 150 cc., and heat to boiling. Identify ammonia by the odor, by use of a piece of litmus paper, or by distilling into water, as directed in the note of Test 11.
NOTE-cyanamide is completely precipitated by silver nitrate in caustic soda solution. The addition of the magnesium sulfate to the resulting filtrate, which contains an excess of caustic soda, precipitates magnesium hydroxide and gives the conditions of Test 11.
TEST13. UREAI N ABSENCEOF CYANAMIDE-TOa 25-cc. portion of the solution add 1 drop of methyl red indicator, make exactly neutral with 0.02 N sulfuric acid or caustic soda as required, and then add just enough of the acid to impart a distinct pink color. Suspend 0.1 g. of soy-bean flour in 10 cc. of water by vigorous shaking for several minutes. Add a drop of methyl red indicator and make the suspension exactly neutral with 0.02 N acid or alkali. Add this suspension to the solution under examination and heat for 30 min. at Meeting of the American Electrochemical Society Edward Goodrich Acheson, whose achievements in the electrochemical field have made his name well known to all the world, was honored by the American Electrochemical Society by election to honorary membership in that body a t its twenty-first anniversary meeting, held a t the Hotel Commodore in New York, May 3, 4, and 5, 1923. According t o F. A. J. Fitzgerald, who presented the account of the man and his work, Dr. Acheson’s outstanding characteristic and that which has contributed most to his success, is his ability to choose his objectives carefully and to drive straight to them without being sidetracked by side issues. Dr. Acheson was one of the founders of this Society. There were 250 in attendance a t the meeting. The secretary reported that the publication program of the Society had been brought up to date, and the treasurer’s report showed a healthy condition of finances. The Committee on Radioactivity recommended that an effort be made to collect all papers on this subject into one journal, preferably that of the Society. The Membership Committee reported a present membership of 1784, a net loss of 211 over a year ago. Symposia on “The Electrochemistry of Gaseous Conduction,” the leadership of Duncan MacRae; “Electrolytic Refining, under F. R. Pyne; and a round-table discussion of “Electric Furnace Brass Foundry Practice,” under Crosby, Lyon, and Elliott, were announced for the September meeting. Symposia on “The Utilization of Chlor,i,ne,” under A. H. Hooker, and on “Organic Electrochemistry, under C. J. Thatcher, were announced for the spring meeting of 1924. The next meeting will be held in Dayton, Ohio, on September 13, 14, and 15, 1923.
uncia
50”. (Color change, pink to yellow, presence of urea.) Roughly determine the quantity of urea present by titrating the liberated ammonia with 0.02 N sulfuric acid, NoTEs-(~) The soy-bean flour is prepared by peeling and drying the soy beans, grinding, and screening through an 80mesh screen. The prepared enzyme is also satisfactory for this test. (2) The color change usually becomes apparent within 2 or 3 min. Sometimes the indicator is bleached during the incubation, in which case it is necessary to add another drop when the incubation is finished. (3) This test depends upon the conversion of urea t o ammonia by the ureolytic enzyme. Of the ten nitrogenous forms listed in this scheme, only cyanamide interferes. the interference of cyanamide is due to the fact that a t incubation temperatures it may decompose to produce urea. Cyanamide solutions, however, are relatively stable when practically neutral, as in the present case, and unless very large amounts of cyanamide are present a positive result in Test 13 is conclusive fqr urea. If large amounts of cyanamide are present, a positive result in Test 13 should be confirmed by Test 14. If Test 13 is negative, pass on to Test 15.
TEST14. UREAI N PRESENCE OF CYANAMIDE-TO a 25-cc. portion of the solution add 2 cc. of strong ammonia and then 10 per cent silver nitrate, drop by drop, until no more precipitate is formed. Shake to coagulate the precipitate, filter, and wash the precipitate once with cold water. Add to the filtrate hydrochloric acid, drop by drop, until it is just acid, filter off the silver chloride, and wash once with cold water. Now add methyl red indicator, make the filtrate exactly neutral with 0.02 N alkali and acid, and proceed as in Test 13. NoTE-The cyanamide is removed as silver cyanamide and the excess silver is then precipitated as silver chloride. This procedure for the elimination of the cyanamide is chosen in preference t o that employed in Test 12 because urea is carried down with the silver precipitate when the precipitation is made with silver nitrate and caustic soda.
TEST15. NITRATE(RINGTEsT)-Mix a S-cc. portion of the solution with an equal volume of saturated ferrous sulfate solution. Place the mixture in a test tube and add 2 cc. of concentrated sulfuric acid, pouring the acid down the side of the tube, held in an inclined position. (Brown ring, presence of nitrate.) The following officers were elected for the ensuing year: President: A. T.HINCKLEY Secretary: COLING FINK V i c e Presidents: LAWRENCE ADDICKS G. K . ELLIOTT HENRYHOWARD Treasure*: F. A. LIDBURY
Managers: F. M. BECKET C. B. GIBSON R. A. WITHERSPOON
Gifts to Chemists’ Club At the twenty-fifth anniversary of the Chemists’ Club, New York, on May 2, W. H. Nichols, one of the original members, took occasion to present the club with five hundred shares of stock in the Chemists’ Building Company, owners of the building in which the club is situated. The original issue oE stock of this company was 5000 shares, representing a total capitalization of $250,000, which was reduced by the will of Morris Loeb to about $175,000. This birthday present from Dr. hTicholsgives the club ownership of $116,700 of the stock now outstanding. The following officers were elected to serve for the coming year: Pvesident: F. J. METZGER Treasuuer: A. G ROBINSON Resident V i c e President: ALLEN Secretary: H. G. SIDEBOTTOM ROGERS Trustees: A. A. HOLXES,S K . R&ED Nonresident Vice President: E. R. WEIDLEIN
On account of the death of Mr. Reed between the time of balloting and the election, nominations to fill his office were called for from the floor and T. R. Duggan was elected. A second birthday present to the club on this occasion was given by A. G. Stillwell in the form of his part of the bond issue made by the club for acquiring the Annex.
