solve in water, add 25 cc. of nitric acid (1 to 3), add sodium bismuthate and complete as in the regular bismuthate method for manganese as given under "Waters1."

Evaporate the solution from 13 to about 50 cc., make slightly alkaline with ammonium hydroxid and add, while still hot, ammonium oxalate solution, drop by drop, so long as any precipitate is produced, adding a few cc. in excess to convert the magnesium also into oxalate. Heat to boiling, allow to stand for 3 hours or longer, decant the clear solution on the filter, pour 15-20 cc. of hot water on the precipitate and again decant the clear solution on the filter. Dissolve the precipitate in the beaker with a few drops of hydrochloric acid, add a little water, and reprecipitate, boiling hot, by adding ammonium hydroxid and a little ammonium oxalate solution. Allow to stand as before and filter through the same filter. Wash free from chlorids with hot water. From this point one of three methods may be used for determining calcium:

(1) Ignite the precipitate and determine the calcium as calcium oxid.

(2) Mix the oxalate precipitate, after incineration of the filter, with finely pulverized and dried ammonium sulphate and drive off the excess of the sulphate by carefully heating the upper portion of the crucible. Determine the calcium as calcium sulphate.

(3) Dissolve the calcium oxalate precipitate in dilute sulphuric acid, wash directly into the beaker and titrate while hot with a standard solution of potassium permanganate.

Evaporate the solution from 15 on the water bath to about 100 cc., add cautiously 20 cc. of concentrated nitric acid. Cover the beaker and evaporate to dryness on the hot plate to remove the ammonium salts. Add 5 cc. of hydrochloric acid and evaporate nearly to dryness. Dissolve the residue in hot water and a small amount of hydrochloric acid. If necessary, filter the solution and wash the filter paper with about 100 cc. of hot water. Precipitate the magnesium as magnesium ammonium phosphate by the addition of 3 cc. of a 10% ammonium phosphate solution and sufficient ammonium hydroxid to make the solution slightly alkaline. Stir the solution vigorously. Allow to stand 15 minutes; add 15 cc. of ammonium hydroxid and allow the precipitation to proceed overnight. Filter, wash the precipitate with 2% ammonium hydroxid solution, place in a porcelain crucible or filter in a platinum Gooch. Ignite and determine as magnesium pyrophosphate (Mg2P2O;).

Evaporate 100 or 200 cc. of the solution from the original fusion nearly to dryness on a water bath to expel the excess of acid; then add 400 cc. of water; heat to boiling and add, drop by drop, a 10% hot barium chlorid solution until no further precipitation occurs. Continue near the boiling point for about 5 minutes; allow to stand for 5 hours or longer in a warm place, pour the liquid on a tared Gooch or on an ashless filter, treat the precipitate with 15-20 cc. of boiling water, transfer to the filter, and wash free from chlorids with boiling water. Dry the filter, ignite over a Bunsen burner, and weigh as barium sulphate.

For the determination of sulphur as sulphates, agitate the soil with water for 7 hours, proceeding otherwise as directed under 24.

1 Assoc. Official Agr. Chemists, Methods, 1916, 47.

Place 10 grams of sodium peroxid in an iron or porcelain crucible and thoroughly mix with it 5 grams of the soil. If the soil has very little organic matter, add a little starch to hasten the action. Heat the mixture carefully by applying the flame of a Bunsen burner directly to the surface of the charge until the action starts. Cover the crucible until reaction is over and keep at a low red heat for 15 minutes. Do not allow fusion to take place. By means of a large funnel and a stream of hot water, transfer the charge to a 500 cc. volumetric flask, acidify with hydrochloric acid, and boil. Cool and make up to the mark. If the action has taken place properly, there should be no particles of undecomposed soil in the bottom of the flask. Allow the silica to settle and draw off 200 cc. of the clear solution.

Precipitate the iron, aluminium, and phosphorus with ammonium hydroxid; filter, wash several times with hot water, return the precipitate to the beaker, and dissolve the precipitate in hot hydrochloric acid, pouring the acid upon the filter to dissolve any precipitate remaining. Evaporate the solution and washings to complete dryness on a water bath. Take up with dilute hydrochloric acid, heating if necessary, and remove the silica by filtration. Evaporate the filtrate and washings to about 10 cc., add 2 cc. of concentrated nitric acid, and neutralize with ammonium hydroxid. Add nitric, acid until the solution is clear, avoiding an excess. Heat at 40-50°C. on a water bath add, 15 cc. of molybdate solution, keeping at this temperature for 1-2 hours. Let stand overnight, filter, and wash free of acid with 0.1% ammonium nitrate solution, and finally, once or twice with cold water. Transfer the filter to a beaker, and dissolve in standard potassium hydroxid (1 cc. = 0.2 mg. of phosphorus), titrate the excess of potassium hydroxid with standard nitric acid, using phenolphthalein as an indicator.

Proceed as in the sodium peroxid method and then complete the determination as follows:

Allow to stand for 3 hours at a temperature not above 60°C., filter on a small filter paper or on a Gooch crucible and wash with cold water until two fillings of the filter do not greatly diminish the color produced with phenolphthalein by 1 drop of standard alkali. Return the filter and precipitate to the same beaker used for precipitating the phosphomolybdate, dissolve the yellow precipitate in standard sodium or potassium hydroxid, add a few drops of phenolphthalein solution and titrate the excess of alkali with standard acid; 1 cc. of the standard alkali should be made to equal 0.0005 gram of phosphorous pentoxid (P2O5).

20

Magnesium Nitrate Method.

Place 5 grams of soil in a porcelain dish. Moisten with 5-7 cc. of magnesium nitrate solution'. Dry on the water bath and burn off the organic matter at low redness. Cool, moisten slightly with water, add 10 cc. of concentrated hydrochloric acid, and digest for 2 hours on the water bath, keeping the dish covered with a watch glass and stirring 2 or 3 times during digestion. Make up to 250 cc., mix well, and transfer to a dry folded filter, pouring back on the filter until the solution runs through clear. Make the determination on aliquots corresponding to 2 or 4 grams of the soil, depending upon the amount of phosphorus present. Dry, take up with hydrochloric acid and water and filter, the filtrate and washings not exceeding 30-40 cc. Make alkaline with ammonium

1 Assoc. Official Agr. Chemists, Methods, 1916, 2.

hydroxid, and dissolve the precipitate with concentrated nitric acid, using a slight excess. Add gradually, while shaking, 5-15 cc. of molybdate solution1, shaking thoroughly. Keep the solution at 40-50°C. for 1 hour, let stand overnight at room temperature, filter. and wash well with cold water. Return the filter and the precipitate to the same flask and determine phosphorus volumetrically, using standard potassium hydroxid and nitric acid.

Fuse 0.5 or 1 gram of soil (ground to impalpable powder) according to the J. Lawrence Smith method for total alkalies2. Transfer the fused mass to a porcelain dish, slake thoroughly with hot water, and grind finely with an agate pestle. After washing five times by decantation with hot water, transfer to a filter and wash well, 300 cc. of wash water being sufficient. To the filtrate add 10 cc. of concentrated hydrochloric acid, and evaporate as nearly as possible to dryness. Take up with hot water and 2 cc. of hydrochloric acid, filter with suction through a small filtering medium into a 150 cc. Jena beaker, to remove the material which would render final filtration extremely slow. If the determination of sodium is desired, evaporate to dryness in platinum and determine sodium by difference from the mixed chlorids. Concentrate the solution to 30 cc., add 1.5 cc. of a platinic chlorid solution (10 cc. containing 1 gram of platinum), evaporate to a sirupy consistency, and add 15 cc. of acidulated alcohol (to 2 liters of 95% alcohol add 152 cc. of hydrochloric acid, sp. gr. 1.20, and pass hydrochloric acid gas into solution to make it 2.25 N). Filter through a Gooch crucible, using suction, wash with 80% alcohol, then with ammonium chlorid solution, saturated with potassium platinic chlorid, and finally with 80% alcohol. Dry for 1 hour at 120°C. to remove alcohol, and weigh. Dissolve the precipitate with hot water, using suction, dry and weigh again.

22

QUALITATIVE TEST FOR SOIL REACTION.

Litmus Paper.

Place approximately 50 grams of air-dry soil in a small porcelain evaporating dish freshly rinsed with water. Add water and mix to a thick paste. By means of forceps, lay upon this a strip of the best grade of litmus paper. Press firmly against the soil by means of a clean spatula or glass rod, keeping the upper surface of the paper free from soil. Protect and permit to stand for 30 minutes, then note the color of the litmus paper. 23

DETERMINATION OF NITRATE NITROGEN.

Place 100 grams of air-dry soil in a mortar or porcelain dish, add, with constant stirring, 1 gram of lime, and 200 cc. of water. Allow to settle for 10-20 minutes. Filter directly through an ordinary filter paper and obtain a clear solution. Evaporate 25 cc. of the filtrate on the water bath. Cool, and add 2 cc. of phenoldisulphonic acid. Triturate thoroughly with a clean glass rod, add 25 cc. of water and strong ammonium hydroxid or potassium hydroxid, drop by drop, with constant stirring, until a permanent yellow color is obtained. Compare the solution in a colorimeter with a standard solution prepared in a similar manner to the unknown3.

In the cases of solutions containing more than 6 parts per million of chlorin, those containing sulphates, or those which are deeply colored by organic matter, one of the reduction methods should be employed for making the nitrate determination*.

1 Assoc. Official Agr. Chemists, Methods, 1916, 1.

2 Ibid., 27.

3 Ibid., 37.

* Ibid., 38.

24

DETERMINATION OF ALKALI SALTS.

To 100 grams of soil in a 500 cc. bottle, add 250 cc. of water. Stopper, shake thoroughly and allow to stand overnight. Filter through a Pasteur-Chamberland filter. Evaporate 50 cc. of the filtrate in a platinum dish on the steam bath to dryness. Ignite at a low red heat to drive off organic matter. Cool in a desiccator and weigh for total salts. Then dissolve the residue in a platinum dish in 10-15 cc. of hot water. Make up to 40 cc. in a graduated cylinder. Take 10 cc. and titrate with N/10 silver nitrate for chlorids. Take 10 cc. and titrate with N/10 hydrochloric acid for sodium carbonate. Determine sulphates by difference. When much gypsum is present, the solution of the salts in hot water must be filtered through a small filter, the gypsum weighed separately, and subtracted from the total amount of sulphates.

Committee on the Revision of Methods of Soil Analysis.

Adopted. Methods adopted as the tentative methods of the association for the analysis of soils.

It was moved, seconded, and adopted that the N/5 acid digestion of soils be deleted.

REPORT OF COMMITTEE ON RESOLUTIONS'.

Resolved, That this association record its deep regret at the loss of its esteemed fellow member, R. E. Stallings, who died July 11, 1917. Mr. Stallings has held the office of State Chemist of Georgia for the past ten years and has been a regular attendant at the meetings of this association since 1909. He was active and effective in regulatory work and has made his influence felt in his chosen field.

Resolved, That this testimonial be spread upon the records of the association and that the secretary be instructed to furnish a copy to his immediate family.

It is with great regret that we record the loss of one of our active members, W. J. Jones, jr., of La Fayette, Indiana, whose death occurred at his home August 31, 1917. As State Chemist of Indiana, Mr. Jones was distinguished by his creative work, and devoted years to the organization of efficient fertilizer and feeding stuff control. He was also an 1 Presented by A. S. Mitchell.

investigator in analytical research and made valuable contributions to our knowledge of methods relating to plant foods. His cordial manner endeared him to all with whom he came in contact.

Resolved, That it is the sense of the Association of Official Agricultural chemists that the death of Mr. Jones is a distinct loss to agricultural science and especially to workers concerned with legislation for the public welfare.

Resolved, further, That the secretary be instructed to send a copy of this resolution to Mrs. Jones.

Resolved, That the thanks of the association be tendered to the management of the New Willard Hotel for the use of the Assembly Room and for the many courtesies extended to the association and its members.

Resolved, That it is the sense of the association that much of the success of the meeting is due to the painstaking care and efficient work of Miss Nellie A. Parkinson, not only at the time of the meeting but throughout the year.

Resolved, That a vote of thanks be extended to the retiring president, J. K. Haywood, for the able and impartial manner in which he has presided over this session.

Respectfully submitted,

A. S. MITCHELL,

C. H. JONES,

W. D. BIGELOW,

Committee on Resolutions.

Adopted.

It was moved, seconded and adopted that the place and time of the next meeting be referred to the executive committee with power to act.

The convention adjourned.