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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
for very rough work is also given in Lunge’s Handbook and is as follows: Thin milk of lime is poured into the cylinder and the reading of the hydrometer is taken quickly before the lime subsides. For thick milk of lime employ a somewhat wide cylinder, put the hydrometer in without using any force and t u r n the cylinder slowly around, so t h a t i t receives a slight shaking until the hydrometer ceases t o sink. The following table is valid for 15’ C.:
form, and t h a t there is another source of error which compensates for the occlusion. The second source of error is the diminished volume of the solute due t o the volume occupied by the precipitates formed on addition of ammonia and ammonium oxalate. Breckenbridge,’ Porter and Kenny,2 Bell,3 and Shiver4 have studied certain errors occurring in the official method, laying particular stress on occlusion and the solubility of the precipitate. Wiley5 calls attention t o “The remarkable facility with which potash beTABLE11-AMOUNT OF LIME IN MILK OF LIME (Calculated from Blattner) comes incorporated with the precipitates of other G. CaO Lbs CaO Degrees G. CaO Lbs. CaO Degrees bodies.” E-Iibbard6states t h a t occlusion “may amount Twaddell per liter per cu. f t . Twaddell per liter per cu. f t . 2 11.7 0.7 28 11.1 177 t o from I t o I O per cent of the original amount of 11.9 4 1.5 190 30 24.4 12.7 6 the potash.” Garrigues7 in reporting a new modi203 32 37.1 2.3 216 34 49.8 13.5 3.1 8 fication gives some good results on the discrepancies 36 229 62.5 14.3 3.9 10 242 15.1 4.7 38 12 75.2 of the official method, showing among other things 15.9 5.5 40 14 255 87.9 16.7 6.3 42 268 16 100 t h a t the loss from occlusion varied from 0.11 t o 0 . 2 0 17.6 7.1 44 281 18 113 18.4 46 294 7.9 126 20 per cent on six samples run by him. One of us5 has 19.2 22 307 8.7 48 138 32 1 20.0 9.5 24 153 found t h a t more than 0.5 per cent of potash was 5 0. 26 10.3 .. .. 164 .. occluded by the ammonia precipitate in certain samples. 608-12 LAWBUILDING Robinsons and Wintong have studied the character BALTTMORE, MARYLAND and magnitude of certain errors in this method, and the influence of concentration on the accuracy of t h e determination, with startling results. Smithlo in a A STUDY OF THE DeROODE METHOD FOR THE general discussion on occlusion remarks, LA^ is well DETERMINATION OF POTASH IN known, many insoluble compounds which are precipiFERTlLIZER MATERIALS tated in the course of analytical processes possess the By T. E. KEITT AND H. E. SHIVER property of carrying down and retaining certain soluble Received July 25, 1917 salts in such a manner t h a t the latter oftentimes canDeterminations of potash have been made in America not be removed, even by prolonged washing.” for the past thirty years b y a method first proposed Chemists, realizing the need of a n improved method, by Lindol in 1881 and modified by Gladding2 in 1885. have suggested many processesll none of which have The Lindo-Gladding method is familiar t o every chemshown sufficient merit t o replace the Lindo-Gladding ist and does not need repetition here; i t has been method. The perchlorate method received special adopted b y t h e Association of Official Agricultural attention, and for a time threatened t o replace the chemist^.^ “The process depends upon the fact t h a t Lindo-Gladding method, but the latest results may be potassium platino-chloride is insoluble in strong alsummarized as follows: “ T h e perchlorate method cohol, and the easy solubility of the associated salts, for the determination of potash was found less suitable for instance sodium, in the same reagent.”4 I n this than the platinum method. I t is longer, more difficult method th’e earthy bases have t o be removed before and more expensive a s t o reagent^."^ precipitating the potash, necessitating the addition A method based on the principle of moist combusof reagents and their subsequent removal by precipition was proposed by DeRoode12 in 189; and modified tation and filtration, which does not contribute t o by Vietch13 in 1905,who says, “ I t is unfortunate t h a t the ease or the accuracy of the determination. The fertilizer manipulators have contended t h a t more attention has not been called t o the method the Lindo-Gladding method does not account for all of Moore14 (DeRoode) for in i t many of the preliminary of the water-soluble potash. Likewise, i t has been operations are omitted and i t is a t once the simplest recognized by certain chemists t h a t this method does 1 “Potash Tests in Mixed Fertilizers,” THIS JOURNAL, 1 (1909), 409; not obtain all of the One of us7has shown “Potash Tests in Commercial Fertllizers,” I b z d . , 1 (1909), 804. 2 “Loss of Potash in Commercial Fertilizers,” Ibid., 1 (1909), 304. t h a t there are grounds for the manipulators’ conten3 “The Estimation of Potash,” Chem. News, 79 (1899), 135. tions t h a t our present method of analysis does not 4 “The Determination of Potash a s Perchlorate,” Ibid., 79 (1899), account for all of the potash present in water-soluble 265. “Original Method for Potash Determination,” Chem. N e w s , 44 (1881), 77. 86. 97. 129. 2 “Improvement on Lindo ,Method,” U. S. Dept. of Agr., Div. of Chem., Bull. 1885, 7, 38. a A. 0. A. C., U. S. Dept. of Agr., Bureau of Chemistry, Bull. 107. 4 Wiley, “Principle and Practice of Agriculture Analysis,” 11 (1895), 540, 554, 555, 570. 5 Lunge’s “Technical Methods of Chemical Analysis,” P a r t 11, 1 (1908), 526. 6 Hintz and Weber, Chem. Anal. Anorg., 1896; Kdrper, Z. anal. Chem., S5, 685. 1 Keitt, “Potash in Mixed Fertilizers,” South Carolina Agricultural Experiment Station, Bull. 173 (19131, 11. 1
5
Loc
8
“A Study of Determination of Potash,” THIS JOURNAL,9 (1916),
Lit.
505. 7 “The Determination of Potash in Manures,” J . A m . Chem. Soc., 17 (1895), 47. 8 “Some Sources of Error,” Ibid., 16 (1894), 634 9 “On Some Conditions Affecting, etc ,” I b z d , 17 (1895), 453. 10 “Contamination of Precipitates in Gravimetric Analysis,” 1917. $ 1 Hicks, “A Rapid Modified Chlorplatinate Method, etc ,” THIS JOURNAL, 5 (1913), 650. 12 “The Determination of Potash in Kainite,” J A m . Chem. Soc., 17 (1895), 85, 86 18 “The Estimation of Potash in Soils, etc ,” I b i d , 27 (1905), 56. 14 “On the Determination of Potash, etc ,” I b i d , 20 (1898), 340.
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a n d shortest, and possesses a high degree of accuracy.” However, the method has been allowed t o stand unperfected in details and unnoticed. This method eliminates all of t h e preliminary precipitation, filtration, a n d incineration, with its accompanying sources of error due t o occlusion, diminished volume and sputtering, besides loss of time and some of the personal equation due t o lessened number of operations. A method very similar t o DeRoode’s was suggested b y L6sche.f Much work has been done in the laboratory of the South Carolina Experiment Station using t h e DeRoode method as a skeleton, and the final results show a very high degree of accuracy, also the modified process obviates the objections of the chemist and the manuf acturer. The method is applicable t o all commercial fertilizers, including concentrated salts. The details of t h e method follow: I O g. of t h e sample are placed in a 500-cc. flask and 300 cc. of water added. The contents of the flask are maintained a t boiling temperature for approximately 30 min., cooled and diluted t o volume. After allowing t o stand until t h e material has settled, filter and draw out 5 0 cc., a n aliquot representing one gram. Place the aliquot in a porcelain dish and add 3 t o 5 cc. of nitric acid t o destroy any organic matter t h a t may be present.2 Evaporate t o dryness over a water bath, take up with hot water and a n excess of hydrochloric acid. Evaporate again t o dryness, take u p with hot water, adding several drops of hydrochloric acid, and enough platinic chloride t o precipitate all of t h e potash present. Thus all of the details through the precipitation are carried out on one bath, in almost one operation, and in a very short time. Cover t h e precipitate with the acidulated alcohol, the method of preparation of which is described later. Allow t o stand for 1 5 t o 20 min., in which time all iron, aluminum, and magnesium will dissolve; filter, and wash with t h e acidulated alcohol solution until the runnings are colorless, washing free of the excess of platinic chloride. Next wash well with ammonium chloride (saturated with KzPtCle). This washing should be thorough, for the accuracy of the method is largely dependent upon this operation; 6 or 7 washings usually suffice. The function of the ammonium chloride wash is the same as in the LindoGladding method. Wash thoroughly with 95 per cent alcohol t o remove the ammonium chloride; then dry and weigh the precipitate and calculate results as in the older method. The preparation of the acidulated alcohol is as follows: To each 1000 cc. of 95 per cent alcohol add 75 cc. of conc. hydrochloric acid, then pass dry hydrochloric acid gas into the mixture until I cc. of the alcohol neutralizes 2 . 2 5 cc. normal potassium hydroxide,h4 using phenolphthalein as an indicator. The hydrochlorio acid gas may be prepared by using C. P. sodium chloride and concentrated sulfuric acid, or by heating 1 2
“The Estimation of Potassium,” Chem-Ztg., a0 (1896), 38. Crookes, “Select Methods in Chemistry Analysis,” Second Edition,
1886, p. 33. 8
Lac. cit.
4
Bear and Salter, “Methods in Soil Analysis,” West Virginia Agr.
Expt. Sta., Bull. 160 (1916). 10.
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concentrated hydrochloric acid and first passing the gas through sulfuric acid and then into the alcohol. The solvent action of this acidulated alcohol on potassium chloroplatinate is about equal t o t h a t of the Lindo ammonium chloride solution, which is about one-third t h a t of ordinary 80 per cent alcohol. Or, if expressed numerically, one gram of pulverized potassium chloroplatinate was digested for t w o hours in 500 cc. of acidulated alcohol, a t room temperature. T h e solvent action under these conditions was found t o be one p a r t in 60,000.~ The ammonium chloride is made u p b y adding t o each 1000 cc. of water 2 0 0 g. of ammonium chloride and saturating in the cold with potassium chloroplatinate. The acids used are C. P. concentrated. Whatman’s filter papers No. 42 (9 cm.) were used on 130 mm. funnels. Drying was effected in a Freas electric oven a t a temperature of I I O O C. for I‘/Z hours. Porcelain dishes are used, efitirely replacing p l a t i n u m dishes which m a y be liberated for use in the arts and im the manufacture of munitions. The following work was done in this laboratory t o test the new method with commercial salts. A solution containing I O g. of potassium chloride and another containing I O g. of potassium sulfate were made and analyzed by this method. The potassium chloride by theory should give 63.20 per cent KzO; the results obtained b y analysis were 63.12 per cent and 63.04 per cent, showing a n average of 63.08 per cent or 99.81per cent of theory. The potassium sulfate theoretically contained 54.20 per cent KzO; the results obtained by analysis were 54.08 per cent K20 and 54.08 per cent KzO, being identical and 99.78 per cent of theory. Some samples collected b y t h e State Board of Fertilizer Control were analyzed. These samples are representative of commercial fertilizers as found on the open market. The following results were obtained b y ( I ) the Lindo-Gladding method, ( 2 ) t h e Lindo-Gladding method plus occluded potash, obtained by repeated solution and precipitation of the ammonia and ammonium oxalate precipitates, and (3) the modified method: TABLE I-COMPARISONOB LINDO-GLADDINQ METHOD,LINDO-GLADDINO METHOD PLUS OCCLUDED POTASHAND MODIPIED
58A 58B 160A 160B 547A 547B 850A
3.15
3.28
2.71
2.89
1229A 1229B
3.10
850B
.... ....
5.98
i:bi
.... ....
.... .... 6.22 .... 2.86 .... 3.22
....
3.33 3.35 2.97 2.97 6.24 6.22 2.94 2.95 3.33 3.26
0.18 0.20 0.26 0.28 0.26 0.24 0.26 0.27 0.23 0.16
0.05 0.07 0.0s 0.08 0.02 0.00 0.08 0.09 0.11 0.04
... ... ... 0:ciiz ... ... ... ... ...
... ... ... 0:%2 ... ... ... I . .
...
The above table shows t h a t the modified method gives a n average of 0.062 per cent more water-soluble potash t h a n the Lindo-Gladding method plus occluded potash obtained by repeated solution and precipitation of the precipitates formed in the flask preparatory t o 1
Lac. cit.
.
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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
making the determination as officially directed. Furthermore, t h e modified method shows a n average increase of 0.232 per cent over the Lindo-Gladding method. There is no doubt t h a t this increased amount of potash is present in water-soluble form and is not accounted for by the official method, because one of us1 has shown t h a t every time t h e precipitate formed b y ammonia and ammonium oxalate in t h e flask is dissolved and precipitated, the filtrate contains potash. The amount of potash obtained by repeated precipitation and filtration was never as much as the theoretical when pure salts were used. I n order t o ascertain whether all potash is determined b y the new method, the following synthetic solutions were analyzed by the methods compared in Table I : Solution I contained potassium chloride and ferric sulfate equivalent t o 5.99 per cent G O and 10.31 per cent Fe203. Solution 2 contained potassium chloride and tricalcium phosphate equivalent t o 5.99 per cent K2O and I O per cent Ca3(P04)2. Solution 3 contained potassium chloride, iron, and tricalcium phosphate equivalent t o 5.99 per cent K 2 0 , 10.31 per cent Fe203, and I O per cent Ca3(P04)2. Solution 4 contained potassium chloride, iron, tricalcium phosphate, and aluminium sulfate equivalent t o 5.99 per cent KzO, 10.31 per cent Fe203, I O per cent Ca3(POr)sand I O per cent &O3. These solutions were intentionally exaggerated as t o content of impurities and the determinations shown are the first and only results obtained, emphasizing the ease and accuracy of the method of determination.
t h e fourth solution. A combination of 10.31 per cent ~ a retention Fez03 and IO per cent C a ~ ( P 0 4 )shows slightly greater than the sum of the retention of the salts added t o separate solutions. This appears t o indicate a slight additional occlusion by the combined precipitates, which occlusion is doubtless greater than i t appears on account of the diminished volume due t o the larger precipitate. The retention incident t o the use of ferric sulfate and tricalcium phosphate amounts t o 0.89 per cent, only 0.029 per cent of which was recovered by three solutions of t h e precipitates and their subsequent precipitation. T h e addition of I O per cent A1203 in the form of aluminium sulfate t o the other two impurities increases the apparent retention only 0.01 per cent, but the diminution in volume by the additional precipitate no doubt compensated for a greater loss which is not apparent. The fact t h a t large retention occurs i n these precipitates serves t o bring out strikingly the results obtained by the new method which are shown in the fifth column of Table 11. These results are consistently slightly lower t h a n theory, but are about within the limits usually allowed for experimental error. The fact t h a t they are within a n extreme range of 0.19 per cent and the further fact t h a t a result slightly below theory is t o be expected make them quite satisfactory, showing the marked superiority of this method over the Lindo-Gladding from the standpoint of accuracy. T o further test the new method more samples were secured from the Fertilizer Control Laboratory and analyzed by both methods with the following results: TABLE111-COMPARISON
SAMPLE
TABLEI1
NO.
SOLUTION
No. 1 2 3 4
5.99 5.99 5.99 5.99
5.61 5.61 5.10 5.09
5.643 5.633 5.129
...
5.94 5.80 5.75 5.78
-0.05 -0.19 -0.24 -0.21
0.33 0.19 0.65 0.69
0.297 0.167 0.621
...
Table I1 shows t h a t soluble iron and aluminium compounds and tricalcium phosphate retain large amounts of potash in t h e Lindo-Gladding method where these compounds are precipitated and t h e potash determined in the filtrate. The indications are t h a t t h e relation is a chemical phenomenon, because of the fact t h a t very little potash is recovered by repeatedly dissolving and reprecipitating the residue. Iron (10.3I per cent) retained 0.38 per cent KzO, only 0.033 per cent of which was recovered i n t h e filtrate by dissolving and reprecipitating three times in 400 cc. of solution. Tricalcium phosphate ( I O per cent) retained 0.38 per cent KzO, 0.023 per cent of which was recovered in three combined filtrates. Aluminium salts were not used alone with potassium chloride on account of t h e similarity of their properties t o those of iron salts, but aluminium sulfate was included in 1 LOC. Cit.
221
18 59 74 90 93 160 247 302 311 313 335 356 357 386 421 641 694 770 961 54
LINDO-GLADDINQ METHODWITH MODIFIED METHOD Potash Potash Difference between Reported Determined by De Roode Columns by L.-G. Method 2 and 3 Method Per cent Per cent Per cent OF
4.34 4.45 2.71 4.60 0.90 1.84 4.75 4.61 3.52 2.88 1.64 2.54 0.25
0.88 4.46 4.57 2.79 4.66 0.93 1.84 4.89 4.85 3.59 2.89 1.74 2.71 0.26
0.95
1.10
1.74 1.73 1.38 0.86 2.18
1.97 1.87 1.40 0.93 2.19
0... .90
-0.02 0.12 0.12 0.08 0.06 0.03 0.00 0.14 0.24 0.07 0.01 0.10 0.17 0.01 0.15 0.23 0.09 0.02 0.07 0.01
Table I11 shows a n average gain of 0.085 per cent for the modified method over t h e Lindo-Gladding method on 2 0 samples. I n every case except one the new method gave higher results as was t o be expected. I n the case of the exception the results were very close. I t is t o be expected t h a t the differences between the methods on different samples will be variable on account of t h e varying amounts of impurities present in different mixed fertilizers. The results by the modified method are accurate. I n the Lindo-Gladding method a case might arise where diminished volume due t o large precipitation would more than counterbalance t h e effect of occlusion. This may be t h e case in Sample 18, Table 111. As a general rule, however, the occlusion takes out more potash t h a n t h e content
222
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of the volume that t h e precipitates occupy, this being evidenced b y every result obtained except t h a t on Sample 18. The new method was used by Mr. T. D. Padgett of this laboratory on 6 samples with concordant results. SUM M A R Y
It has been shown that the DeRoode method surmounts the difficulties encountered in the LindoGladding method. These same sources of error are incident to the Anhalt and the Alternate methods t o a greater or less extent. A few of the outstanding advantages of the modified method may be summarized as follows: ease of manipulation; small amount of time consumed, being much
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less than in the Lindo-Gladding method; a much greater degree of accuracy; all incineration, with possible losses from sputtering; precipitation, with its great loss from occlusion; filtration, not adding to the accuracy of the determination due t o the volume occupied by the precipitates; and a great part of the evaporation being dispensed with. Finally, any process t h a t eliminates the use of platinum apparatus without sacrificing accuracy should be welcomed. By avoiding ignition, only porcelain dishes have been used in this method, thus placing a t the disposal of the Government large numbers of platinum dishes now kept by all official and commercial laboratories for the determination of potash. LABORATORY SOUTH
CAROLINA
EXPERIMENT STATION
CLEMSONCOLLEGE,S. C.
LABORATORY AND PLANT BLUE AND BROWN PRINT PAPER: CHARACTERISTICS, TESTS AND SPECIFICATIONS By F. P. VEITCH, C. FRANK SAMMET AND E. 0. REED
Received October 8, 1917
The manufacture of paper for use in blue and brown printing is an important special branch of paper making. The frequent handling and folding t o which this class of paper is subjected in all branches of engineering work and the value attached t o many prints as permanent records necessitate that the paper in addition to the essential properties, t o withstand coating, printing and washing satisfactorily, shall be of exceptionally high quality and great durability. The first photograph produced dates back to about 1802, when Thomas Wedgewood published an article in the Journal of the Royal Institute entitled “An Account of a Method of Copying Paintings upon Glass and of Making Profiles by the Agency of Light upon Nitrate of Silver, with Observations by H. Davy.” In this article it is stated that white paper or white leather when moistened with silver nitrate undergoes no change when kept in the dark, but upon exposure t o the light speedily changes to nearly black. Blue print paper was invented in 1840by Sir John Herschel, and in 1901 brown print paper was patented by Van Dyke. Formerly the best paper obtainable in this country for blue and brown printing came from Germany and France, and though a number of paper makers have made such papers for years it has been exceedingly difficult to obtain a domestic paper of sufficiently high quality to be satisfactory in service. It is only recently t h a t American-made papers t h a t will meet t h e accompanying specifications for “Best Quality” and for “High Quality’’ papers have come to the attention of the Bureau. I n 1910 the Navy Department requested the Department of Agriculture t o investigate the quality of blue and brown print papers and submit specifications under which it could purchase high-grade and durable papers. I n this investigation more than 2000 samples,
including, it is believed, all of the commercial brands of blue and brown print paper, both foreign and domestic, were examined, and from the data thus obtained specifications were issued in 1912 which now serve, with some modifications, as a basis for the purchase of these papers by the Navy Department. Up t o that time, so far as can be learned, no complete specifications for blue and brown print paper had ever been prepared and used in this country. By the aid of these specifications and wiih suggestions from this Bureau, American manufacturers have since made blue and brown print papers which are equal to, and in some respects superior t o the foreign-made papers and which have been found t o meet all the accompanying specifications in every particular An important special branch of paper making has been established in this country, and if the quality of the paper is maintained, engineers may confidently depend on these papers for the most exacting requirements. I n a broad sense high-grade blue and brown print paper is a bond paper of the best quality, preferably all rag stock, so sized as t o be resistant in a proper degree t o the absorption of the sensitizing solution and yet to coat absolutely uniformly. As this class of paper is subjected t o much handling in both the wet and dry condition and in many cases is valuable as permanent records, it should possess high physical properties and be very resistant t o chemicals. Practical and laboratory tests have demonstrated t h a t the most reliable indication of the durability and serviceability of blue and brown print paper is obtained by the determination of its folding endurance.l This test does not, however, indicate the resistance of paper t o tearing when the print is being washed and handled t o remove the soluble salts. This information is best obtained by the determination of the tensile strength2 of the paper when wet, which gives results 1 Veitch, Sammet and Reed, “The Standardization and Accuracy of the Tester for Determining the Folding Endurance of Paper,” Paper, No 12, 20, 13. 2 E. 0. Reed, “A Method for Determining the Strength of Paper when Wet,” THISJOURNAL, 8 (1916), 1003.
