COCA LEAVES.

The results by all methods for coca leaves are so variable that none can be said to be encouraging. The results of the aliquot gravimetric method agree best among themselves, but the titration equivalents show that they must be regarded as too high.

COLCHICUM CORM.

The results for colchicum corm by the pharmacopoeial method are materially higher than by Method II, but also vary relatively more among themselves.

COLCHICUM SEEDS.

Results for colchicum seeds, by both methods, exhibit great variations, and experiments on purifying the residues by a process similar to the latter part of the pharmacopoeial method for colchicum corm showed that the impurities present would render the results entirely unreliable unless they were removed.

In the absence of the referee on tannin, his report was presented by Mr. Tolman, as follows:

REPORT ON TANNIN.

By F. P. VEITCH, Referee.

The referee was unable to obtain the samples desired until very late, and for this reason very few of the twelve or fifteen analysts, who had promised to collaborate, were able to do so and the work was confined to a comprehensive study of the filtration of soluble solids through folded S and S 590 and S and $ 588 paper, the first a high-grade paper and the latter a cheaper paper of ordinary grade. For a number of years the No. 590 paper has been unsatisfactory for use in soluble-solids determinations, as it is not uniform and is too weak to stand the weight of the solution after the paper is folded.

In a study which the referee had made, using a large number of different extracts, it was found that the No. 588 paper gave results agreeing closely with those with the No. 590 paper, except in the case of quebracho. Reed had previously obtained satisfactory results with No. 588, but only on hemlock and lentiscus. The referee's favorable results led him to submit the paper to collaborative tests, as both time and expense would be saved if it could be used.. The following circular letter was sent out:

DIRECTIONS FOR TANNIN WORK, 1907.

DEAR SIR: I am forwarding you to-day three samples of extracts in which the following determinations are to be made in triplicate: (1) Total solids.

(2) Soluble solids, using 15 cm 590 S and S folded filters. (3) Soluble solids, using 15 cm 588 S and S folded filters.

Make all dryings on the bottom shelf of a boiling-water oven, drying for 12 hours.

Dissolve the following quantities of extracts in 2,700 cc of water at 80° C: Sample No. 1, 18 grams; Sample No. 2, 42 grams; Sample No. 3, 15 grams.

Allow to cool overnight to 20° and dilute to 3,000 cc. In these solutions determine total and soluble solids as follows:

Total solids: Thoroughly mix the solution, immediately pipette 100 cc into a tared dish, evaporate, and dry as directed.

a J. Soc. Chem. Ind., 1902, 21: 691.

Soluble solids: Add 75 cc of solution (kept at from 20° to 25° C during filtration) to 2 grams of kaolin (free from soluble salts); stir, let stand 15 minutes, decant, and discard as much as possible of the supernatant liquid. Again add 75 ce of the tannin solution to the kaolin, stir, and pour immediately on a folded filter. Keep the filter full and the funnel and receiving vessel covered. Reject the first 150 cc of filtrate, evaporate and dry the next 100 cc (which must be as clear as practicable) as directed.

**

If you have not the kind and size of filter paper specified please communicate with the referee before proceeding further.

The results reported are given in the following table:

TABLE I.-Determinations of total and soluble solids in three extracts, comparing S and S 588 and 590 filter papers.

a UnderTime" the first figures show the time required for the first 150 cc; the second figures for the next 100 cc.

No final conclusion can be drawn from these few results, but it is quite evident that the S and S 588 paper gives slightly lower results than the 590 paper under the conditions of filtration, which, it must be remembered, were devised for use with the 590 paper. The results agree in general with those that have been previously obtained, and it seems probable that with some modification in the method of filtration, such as the filtration of about 200 cc before collecting the portion for analysis, the results would agree with those obtained with the 590 paper. Such a procedure would, of course, lengthen the time of filtration, and this would not be desirable.

The time of filtration with the 588 paper was, as a rule, slightly shorter than with the 590 paper. Mr. Smoot observed that the temperature at which filtration was conducted affected the speed of filtration as well as the percentage of soluble solids; the cooler the solution the more slowly it filtered. Mr. Smoot also made some determinations with an asbestos-kaolin mat on a Buckner fun

nel, using suction as proposed by Reed at the recent meeting of the Association of American Leather Chemists. The results were as follows:

TABLE II.-Determination of soluble solids in tannin extracts using an bestos-kaolin mat, at 21° C.

as

The first figure under "Minutes" shows the time required for the first 150 cc; the second figure for the next 100 cc, with the exception of the first two results on Sample 1 and both results for Sample 3 which were obtained after filtering only 100 cc in each case.

As will be seen, the time required for filtration when the asbestos mat was used was greatly reduced. When the quantity of liquor rejected was at least 150 cc, the results agreed fairly well with those obtained with S and S 590 paper, except on Sample 2 which gave exceptionally clear filtrates with the asbestos filter. This may account for the low results.

The referee does not recommend a change of papers for filtering soluble solids, as the results obtained with 588 paper, while usually sufficiently close to those by the 590 paper, are apt to be wide on quebracho. Doubtless the 588 paper could be safely used on tannery liquors and other materials of low tannin content.

It is recommended

RECOMMENDATIONS.

(1) That the work on the filtration of tannin extracts be continued with a view to finding a cheap, strong paper as a substitute for S and S 590.

(2) That the method of filtering soluble solids suggested by Reed be given further trial.

(3) That the referee take up the study of methods for the analysis of leather, as such methods are greatly needed.

REPORT ON SOILS.

By J. H. PETTIT, Referee.

The work of the referee on soils for the present year has been mainly a continuation of that undertaken last year. Two of the four samples used were the same as two of those sent out last year, while Samples 1 and 3 were new. The following outline of the work to be done was sent to those desiring to participate:

(a) Determine dry matter upon 5 grams of the air-dried soil by heating five hours in water oven.

(b) Make a preliminary digestion of the air-dried soil in fifth-normal nitric acid at room temperature." Weigh 200 grams of soil into a 2 liter

"U. S. Dept. Agr., Bureau of Chemistry, Bul. 46, Revised, p. 74 (b); Bul. 107, p. 18 (b).

flask and add 2,000 cc of a solution of nitric acid of such strength that, after allowing for the nitric acid neutralized by the soil, as shown by the previous .digestion, there will be left 2,000 cc of fifth-normal nitric acid solution. Digest five hours at room temperature, shaking every half hour. Record the temperature of digestion. At the end of the period shake and filter through a large folded filter, pouring the solution back into the filter until it runs through clear. Evaporate 1,000 cc of the filtrate to dryness, moisten with hydrochloric acid, dry again, heat one hour at 110° C to insure complete removal of acid, take up with hydrochloric acid and water, heating if necessary, filter out silica, and wash. Evaporate filtrate and washings to about 10 cc. Add 5 ce of concentrated nitric acid, neutralize with ammonia, make barely acid with nitric acid, heat to from 40° to 50° C, precipitate with ammonium molybdate solution, and let stand over night. Filter, wash with 0.1 per cent ammonium nitrate solution until free of acid, and twice with cold water. Dissolve in a standard potassium hydroxid solution, 1 cc of which contains 8.324 mg of potassium hydroxid and is equivalent to 0.2 mg of phosphorus. Titrate the excess with a nitric acid solution, 1 ce of which is equivalent to 1 cc of the potassium hydroxid solution.

(c) Weigh 10 grams of sodium peroxid into an iron or porcelain crucible and thoroughly mix with it 5 grams of soil; if the soil is very low in organic matter add a little starch to hasten the action. Heat the mixture carefully by applying the flame of a Bunsen burner directly upon the surface of the charge and the sides of the crucible until the action starts. Cover crucible until reaction is over, and keep at a low red heat for twenty-five 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 ce measuring flask. Acidify with hydrochloric acid and boil; let cool and make up to the mark. If the action has taken place properly there will 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, aluminum, and phosphorus from the hot solution with ammonium hydroxid; do not allow to settle; filter; wash three or four times with hot water; return the precipitate to the beaker with a stream of water, holding the funnel over the beaker, and dissolve the precipitate in hot dilute hydrochloric acid, pouring the acid upon the filter to dissolve any precipitate remaining. Remove silica and determine phosphorus as in (b). Determine phosphorus, using the alkali carbonate fusion method and getting rid of the silica as suggested above.

(d) Fuse 1 gram of soil according to the well-known J. Lawrence Smith method. Transfer the fused mass to a porcelain dish, slake with hot water, grind finely with an agate pestle, and transfer to a filter. After washing free of chlorids, concentrate the filtrate and washings in a Jena beaker to about 20 cc and filter. Slightly acidify filtrate and washings with hydrochloric acid, concentrate in a platinum dish, and add 14 cc of a platinic chlorid solution (10 cc contains 1 gram of platinum). Evaporate to a sirupy consistency as usual and wash with 80 per cent alcohol and an ammonium chlorid solution. Determine potassium according to the regular J. Lawrence Smith method."

The following laboratories sent reports:

S. D. Averitt, for the Kentucky Experiment Station.

H. D. Edmond, for the Connecticut Experiment Station.

R. W. Thatcher, for the Washington Experiment Station.
G. S. Fraps, for the Texas Experiment Station.

J. H. Norton, for the Arkansas Experiment Station.

J. H. Pettit, for the Illinois Experiment Station.

a U. S. Dept. Agr., Bureau of Chemistry, Bul. 46, Revised, p. 11 (b); Bul. 107, p. 2 (c).

Fresenius's Quantitative Chemical Analysis, p. 422.

Ibid, p. 426.

TABLE I.-Determination of phosphorus soluble in fifth-normal nitric acid. [Parts per million in dry soil.]

TABLE II.-Determination of phosphorus by the sodium peroxid fusion.

TABLE III.-Determination of phosphorus by alkali carbonate fusion.

It is unfortunate that no more work by the standard method was done. The results obtained by the sodium peroxid method show fair agreement with the meager data obtained by the standard alkali carbonate method. TABLE IV.-Determination of total potassium by the regular method.