April, 1912
T € € E J@L-RS,-ILOF IiVDGSTRI;1L
ring rod, are then held a t any temperature for any time desired. The resulting acid phosphate is transferred to a 9 cm. filter paper with water and the citrate-insoluble phosphoric acid determined by the Official Method. Page 3, Bull. 107,Rev. Bureau of Chem. At first this method gave occasional erratic results b u t with practice and care we are now able to get results agreeing practically within the limit of error of the citrate-insoluble method. The results used in this kind of work are averages of three and in most cases four separate analyses. I n this r a y accurate reliable results are obtained This method has many advantages over one using larger quantities of rock. Three of these are: 1st. Large numbers of tests can be carried out with inexpensive apparatus common to every laboratory. 2nd. The temperature at which the tests are held can be easily and accurately controlled. 3rd. A large number of these tests can be made in the time required for one by any other method known to the writer.
There was available a considerable quantity of each of the two samples for the 1909 A. 0.A. C. soil work, and as the average of results from a large number of independent workers is likely to be somewhere near the truth, it was thought that here was an unusually good opportunity to compare the two methods. Four determinations were accordingly made on each of the two soils, under conditions parallel to those used by the A. 0. A. C. workers, and the results are presented in Table I , accompanied b y the Association results on the same. TABLEI. so11 I . ICnorr method. .4nalyst. 3.
2.
1.
4.
0.070
0.085
0.072
0.073 0.065 0.072
0.082
0.073
0.068
...
0.073
...
-__ Av. 0 . 0 7 0
.
,
, .
.
0.083
. . . . . .
ON THE DETERMINATION OF CARBON DIOXIDE I N SOILS.
Up to a comparatively recent time no method had been so thoroughly tried out as to be considered a reliable one for small amounts of carbon dioxide in soils. In 1908, the Association of Official Agricultural Chemists took up the matter of testing the applicability of the Knorr method, and in 1909 a still larger amount of cooperative work was done. The results of the work will presently be presented in tabular form . The method outlined in the author's previous paper1 having been found to yield good results with materials containing a large percentage of carbon dioxide, i t remained t o be seen whether i t would be as satisfactory in cases where the percentage is small. As a preliminary, two determinations were made in a sort of artificial soil containing a known amount of carbon dioxide. A very pure sea sand was ignited for some time to remove all organic matter and decompose such calcium carbonate as might be present from finely divided particles of sea shells and other carbonate materials. This was cooled, and to a v-eighed portion was added enough analy7ed CaCO, to give exactly 0.05 per cent. CO,. A blank determination was first made on the water, reagents, and freshly ignited sand; then two determinations were carried out on the artificial soil. The blank first found was deducted from the titration results, and CO, calculated from the difference. The determinations gave 0.043 and 0.048 per cent. CO,, a n average of 0.0455 as against the 0.05 per cent. actually present, which seemed very satisfactory. THISJOURNAL, 4 , 203-205 (March, 1912).
0 085 0.082
6.
0.074
0.074 0.080
0.080
0.080 0.077
...
0.075
0.080
... ...
0,084
...
... ...
0.077
0,079
. . . . . . 0 085 . . . . . . . . . . . . . . .
_
_
~
_
7.
0.080
_
-
0 . 0 7 3 0.092 0.086 0 . 0 7 9 General av. 0.078
-
1.
2.
3.
4.
5.
6.
7.
0.027
0.027 0.035
0.023 0.021
0.027
0.036 0.036
0.026 0.025
0.031 0 . 0 2 8 0.024 0.035 0.02; ...
0.027 0.027 0.030
0.030
...
0.020 0.022
0.028
.
0.092 0.085
Soil 2. Analyst.
ATLANTA,Gh.
B y LEON T. BOTSSER
.. ... ,
0.075
LABORATORY, SWIFT FERTILIZER WORKS,
Received October 26, 1911.
5.
0.092
Volumetric method.
0.023
.... ...
. . . . . . . . . . . . .
- ~ _ _ _ _ _ _ _ _ .Iv. 0 . 0 2 7
0,031
0 . 0 2 2 0 . 0 2 7 0 . 0 2 8 0.034 General av. 0.028
Comparison of Averages. Soil 1. A. 0. A. C.. \-olumetric.
. . . . . . . . .0 , 0 7 8
. . . . . . . . . 0 . Oi9
... ...
__ 0.025
0.026 0.031 0.031 0.026
...
0.028
Soil 2. 0 028 0.028
The averages given in the Association report are: I , 0.081 per cent.; No. 2 , 0 . 0 2 7 per cent. CO,, b u t these include only the results of the first five analysts, the latter two reporting too late to be included. For the present work all of the results are considered, increasing the probability that the averages are near the truth. The agreement between these revised averages and the ones obtained by the volumetric method is remarkably close, and shows that the latter is thoroughly reliable. On the score of consistent results, the volumetric method is superior to the gravimetric. Thus on Soil I the A. 0.A. C. results range from 0.065 to 0.092,a variation of 0 . 0 2 7 per cent., while the volumetric results range from 0.075 to 0.084,a variation of 0.009 per cent., or just one-third of the former. On Soil 2 , the A. 0. A. C. results run from 0 . 0 2 0 to 0.036, a variation of 0.016 per cent., as against 0.026 to 0.031, a variation of 0 . 0 0 5 per cent. for the volumetric, which, as with Soil I , is practically one-third as great a difference. The method followed was as outlined in the preceding paper,' and in each case I O grams of soil were taken. Soils containing 0.1 per cent. or less of CO, require for titration an acid of strength not exceeding hT/So, since when stronger acids are used the evolved CO, is equivalent to but a fraction of one cc., and too
No.
1
THISJOURNAL, 4, 203.
266
T H E J O U R i V A L OF I N D U S T R I A L A S D E2YGIXEERI-I-G C H E M I S T R Y .
great an error is thus introduced. Occasion may even arise where a centinormal acid is demanded, although the writer has never encountered such a case. Even with N / 5 0 acid a considerable amount of care is necessary in observing end points, and the use of comparison solutions is advisable. There are many ways in which this method seems especially adapted to soil work. Thus boiling the sample in the flask does not cause even the slightest bumping, and the evolved gas comes off smoothly and uniformly. Also, the vigorous boiling possible in this form of apparatus insures a thorough and constant stirring up of the sample, with consequent complete decomposition of the carbonates. One precaution which must be carefully observed, however, is in regard to the degree of heat applied to the flask a t first. Just as the contents are about to begin ebullition there is a tendency to froth, and the flame should be turned down low for a moment until the solution is in full boiling. A curious fact has been noted by several analysts in connection with the amount of a soil sample which should be introduced into the decomposing flask; results with I O grams of soil are almost invariably higher than those with larger amounts. This is illustrated in Table 11, where three independent analysts have obtained results decidedly similar. TABLE
11. Soil 2.
Soil 1 .
7
50
35
10
50
40
20
10
gms. gms. gms. gms. gms. gms. gms. Analyst 6 . . . . . . . . . 0.065 . . . . . . 0,021 . . . . . . . . . Analyst 7 . . . . . . . . . . . . . . . . . . . . . 0.025 0.0225 . . . A. 0. A. C. A v . . 0.078 . . . . . . . . . 0.028 L. T. Bowser.. . . . . . . . 0.061 0.079 0,025 . . . . . . 0.028
.........
An investigation into the causes of this behavior might yield results of considerable value. Judging from the results secured, the titration method is apparently superior to the procedures now in use for the determination of carbon dioxide in soils. I t is far more accurate, the manipulation simpler, results more uniform, and the apparatus itself not in the least fragile. These advantages, coupled with the fact that there are very few precautions to be observed, should make i t of great service in the analysis of soils. In conclusion, the writer desires to acknowledge his indebtedness for many favors to Mr. J . W. Ames, of the Ohio Agricultural Experiment Station, Xr, W. F. Pate, formerly of the same place, and Dr. A . M. Peter, of the Kentucky Station.
THE PHENOMENON OF THE APPARENT DISAPPEARANCE OF THE HIGHER BOILING PHENOLS IN CREOSOTED WOOD AND ITS EXPLANATION. By SAMUEL CABOT.
Received January 18, 1912.
One of the mysteries of the chemistry of wood preservation is the apparent disappearance of the
April, 1912
phenols from timber impregnated with coal tar creosote. The generally accepted explanation has been that carbolic acid and the cresols are volatile and soluble. Most authorities have been content with this explanation. From the logic of the fact, however, i t does not seem to cover the more complex members of the series. Some of those found in creosote are non-volatile without decomposition under ordinary pressure and have been carried over into the distillate by the oil. These phenols are also less soluble than the bases which are found in old treated timber. In an earlier article i t has been shown that the phenols are, if anything, less subject to evaporation than the oil fraction in which they are contained. The only solution to their apparent disappearance would seem t o be that they have been so altered in the process of time that they no longer can be found by the regular method of analysis. In accordance with this theory, experiments were conducted with a view of following and detecting the changes in the phenols of a high-boiling oil on exposure t o the air First, the freshly distilled oil containing 7 . 2 per cent. of tar acid was exposed. I t changed with considerable rapidity from a clear reddish color to a brownish black. The same oil with the phenols removed changed very slightly. O n extracting the tar acids from the blackened oil in the ordinary way with dilute caustic soda, i t became much lighter in color and a black tarry layer separated out between the oily and aqueous liquids. This tarry bubstance was insoluble in benzole and only very slightly soluble in water, though readily so in acetone. On weighing the phenols and tarry matter the results showed phenols, 6.77 per cent.; tarry matter. 0.47 per cent. The original freshly distilled clear oil when shaken with caustic soda precipitated no tarry material. I n the next tests some high-boiling tar acids were exposed on a watch glass for six months. The original phenols were entirely soluble in benzole. Those that had been exposed to the air, however, were only partially so, though readily soluble in acetone. A portion of that soluble in benzole was re-exposed for a period of two months. Again it became partially insoluble. The rest was analyzed for phenols in the usual way. I t precipitated a tarry layer with caustic soda equal to 53 7*of its weight ; the remaining 47 per cent. were recovered from the acidified liquid. The tarry products from both these experiments had a sharp acid taste much stronger than that of the oil, This tarry substance is curious in its behavior. A portion of i t , while insoluble in caustic soda solu. tion is soluble in water, resembling in this respect a soap. After the water-soluble portion has been washed out, some of the remainder becomes soluble again in the original oil or benzole. This can be partially, though not completely reprecipitated by the alkali The remainder which is insoluble in either water or benzole is not changed in this respect by neutralizing with acid. T t would appear from these facts that the phenols
