INDUSTRIAL AND ENGINEERING CHEMISTRY
48
Vol. 15, No. 1
Contamination of Water Samples with Material Dissolved from Glass Containers1" By W. D. Collins and H.B. RifEenburg U. S. GEOLOGICAL SURVEY, DEPALRTM~BNT O F THE INTERIOR, WASRINGTON, D. C.
HE SOLUBILITY of glass in water was suggested by Glass bottles are the best containers for samples of water, Lavoisie9 in 1770 as a probable explanation of certain provided they happen to be good bottles. Even the best results obtained by earlier experimenters who had glass is slightly soluble in water and poor glass may be so assumed that distilled water held for some time in glass soluble as to affect seriously the composition of a sample held vessels did not contain any dissolved mineral matter. Refer- for only a few days. Some bottles of the latter kind that had ences to other articles on this subject and reports of tests of been received in the Water Resources Laboratory were filled the durability of glass are given in a bibliography by Turner4 with distilled water, tap water, and a solution of sodium prepared in connection with studies by Cauwood, English, carbonate (about 0.5 g. per liter), and the contents examined and Turner5 on the resistance to reagents of vessels made from time to time over periods of from 7 to 15 mo. A t from different types of glass. These studies, like those of the same time bottles made of ordinary good bottle glass NicolardotlBand of Walker and Smither,' were made with were tested in the same way. The results for 8 mo. are reference to the quality of chemical glassware developed in shown in Figs. 1,2, and 3. The upper part of each figure shows England, France, and the United States to take the place of the data for the good bottles and the lower part shows the the ware formerly imported. All these authors refer to papers poor ones. by Mylius* and by Foerster,g who published some of the I n water analysis the bicarbonate, carbonate, and hydroxide earlier comprehensive studies on the resistance of glass to radicals are determined by titration of the alkalinity with reagents. Solubility tests are included in the series of standard acid, generally with phenolphthalein and methyl articles by Peddlelo on the development of various types of orange indicators. This regular determination was made on glass. samples from the bottles and all the results were calculated to The necessity for tests of alkalinity of glass ampuls and bicarbonate (HCOs), The original value for bicarbonate was other containers for medicines has been noted by Buhrerll subtracted, and the remainder, the alkalinity in parts per miland by Kroeber12who describe the precipitation of medicinal lion taken up from the bottle, was plotted against the time in months that the solution had been in the bottle (Fig. 1). agents by alkali dissolved from glass containers. The requirements of glass for bottling purposes are dis- It is obvious that the increase in alkalinity is due to sodium cussed in an article by Frink,'3 in which he gives the results hydroxide and this is evident from the actual titrations which of tests on the solubility of different bottles. Analyses of the show decreasing values for bicarbonate and increasing hyglasses are also given. Turner14 reports tests of a number of droxide, with the carbonate increasing to a maximum and English bottles and Bitting16 gives data on the solubility of then decreasing. Filtered samples of the solutions were evaporated to drysome American bottles treated with distilled water and with ness and weighed after heating for 1 hr. a t 180' C. These dilute acid. The results reported by Frink, by Turner, and by Bitting results are shown in Fig. 3. Silica in the residues was deterhave one feature in common. The bottles were nearly all mined in the usual manner and the results are shown in Fig. 2. Two samples of tap water and one sample of distilled water either good or bad. Few were intermediate in character. Some bottles tested by Turner gave up one hundred times as that had been in poor bottles for 12 and 15 mo., respecmuch alkali as the more resistant ones. Nearly all of those tively, were analyzed by the regular procedure followed in the tested by Bitting were quite resistant but the few that were Water Resources Laboratory, which is practically that of the not gave up about ten times as much alkali. This character- Standard Methods of the American Public Health Association. istic appears in some of the tests of chemical glassware. As These results are given in the table, together with an analywould be expected, the glasses with higher percentages of sis of tap water made a t the time the bottles were filled. The results plotted in Figs. 1, 2, and 3 show that the good alkali are usually the ones that give up the largest quantities. bottles did not give up enough soluble material in 6 or 7 This is undoubtedly well known to the manufacturers. mo. to affect an analysis seriously, except for the silica 1 Received June 28, 1922. taken up by the sodium carbonate solution. No determinaPublished by permission of the Director, U. S. Geological Survey. tion of total solids was made on this sample, but the increase 8 Memoires de 1'Academie des Sciences, 1770, 73, 90. must have been considerable. Alkalinity and silica in the 4 J . SOG. Glass Tech., 1 (1917), 213. Further studies reported in I b i d , 2 (1918), 219, 6 Ibid, 1 (1917), 153. distilled water and tap water in the poor bottles increased 235; 3 (1919), 129, 228; 6 (1922), 17, 30. nearly as much in one month as in six. The sodium carbonate * Compt. rend., 163 (1916), 355. solution showed a more regular increase in silica content and 7 Bur. Standards, Tech, Paper 107 (1918). the few samples of distilled water and of tap water tested 2. anorg. Chem., 55 (1907), 233; 8 2. Instrumentenk., 8 (1S88), 267; 67 (1910), 200. after 15 mo. had considerably more silica than a t the end 2. anal. Chem., Si (1892), 241; 83 (1894), 299, 381; Ber., 26 (1892), of 6 mo. 2494. The fact that tap water or distilled water can take up 20 10 J . Soc. Glass Tech., 4 (1920), 3,299; 6 (19211, 72, 195,201. or 40 parts per million of silica from a bottle in a month shows 11 Schweiz. Apoth. Ztg., 56 (1918), 285. 1 2 Phavm. Zentralhalle, 59 (1918), 223, 233; Schweie. Apoth. Zlg , 69 the importance of this question in connection with water (19211, 369, 382. analyses and a t the same time suggests a simple test for sample 18 Trans. A m . Ceram. Soc., 16 (1913), 706. bottles. If distilled water held in a bottle for a month at 14 J. SOG Glass Tech , S (1919). 37. ordinary room temperature has not dissolved more than one 1s Glass Industry, a (1921), 235.
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January, 1923
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
a
FIG. ALKALI DISSOLVED FROMGOODBOTTLES (UPPER)AND FROM POORBOTTLES (LOWER) EXPRESSED AS HCOs
49
SOLIDS (T. s.) DISSOLVED FROM FIG. 2-SILICA (sios) DISSOLVED FROM GOOD FIG. 3-TOTAL GOODBOTTLES (UPPER)AND FROM POOR BOTTLES (UPPER)AND FROM POORBOTTLES (LOWER) BOTTLES (LOWER)
or two parts per million of silica, the bottle is likely to be satisfactory for water samples. An unfit bottle can be detected by titration of the water that has stood in it for a few hours or a week. The table of analyses shows that the large effects on an analysis are in the siIica, sodium, and alkalinity- The changes in carbonate and bicarbonate in the tap Water correspond almost exactb t o the change in sodium. The agreement with those in the are in obtained occasionally when a Sample has been analyzed that has stood too long in a poor bottle and a later check sample has been procured in a good bottle and examined promptly. ANALYSES SHOWING SOLUTIONO F MATERKAL FROM POOR GLASSBOTTLES (PARTSPER MILLION) Distilled TAP WATERWater 15 I Year in Bottle Months in As Drawn' No. 1 2 h.0. 22 Bottles Silica (SiCJz) 8.2 39 53 142 Iron (Fe) 0.15 0.15 0.15 Trace Calcium (Ca) 18 19 18 1.1 Magnesium (Mg). 4.3 3.3 3.2 0.2 Sodium and potassium (Na K) 2.2 18 24 22 Hydroxide radical OH). 0 0 0 Carbonate radicsl tCO3). 0 24 31 34 Bicarbonate radical (HCOs).. 52 41 41 0 Sulfate radical (so&). 19 21 22 4. Chloride (Cl) 4.0 4.0 Nitrate radical (Nod.. 3.9 3.9 3.8 Trace Total dissolved solids at 180' C.. 91 150 177 208 1 Analyzed by C. S. Howard. 2 Analyzed by H. B. Riffenburg.
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.................... ....................... ................... ............... + .. ......... ......... .... ............ ................... ...........
Most natural fresh waters contain an excess of carbon dioxide, and therefore the regular analysis shows the presence of bicarbonate and no carbonate or hydroxide. A few natural waters are deficient in carbon dioxide and some have dissolved from rocks enough sodium silicate to show hydroxide, but these last are very rare. If an analysis of a natural water shows a large proportion of carbonate or any hydroxide, and the silica is over 30 to 40 parts per million, there ik, ground for suspicion that the sample contains dissolved glass. Further investigation may show the Presence of 50 or 60 parts per million of silica in a natural calcium bicarbonate water or larger quantities in a natural sodium silicate water, but mOre frequently it will be found that the high silica and the hydroxide come from solution of the container.
CONCLUSION Samples of water in good bottles will not dissolve enough glass in a month to cause any detectable change in the nary mineral analysis. No significant change will be caused in 6 samples in bad bottles a week, and sometimes a day, may dissolve enough glass to change the character of the water as shown by an analysis, The greatest changes are the increase in silica and sodium, and the ehange of the alkalinity from bicarbonate to carbonate and hydroxide with an increase of total alkalinity corresponding to the sodium. Bottles may be tested for resistance to solution by filling with distilled water and examining the after a month. Titrations with acid and determination of the total solids and the silica will show the extent of the action.
Navy's Recognition of Chemists Urged On December 1, Charles L. Parsons appeared before the Naval Wage Board, Admiral Strauss, chairman, to discuss the status of chemists in the Navy and to urge that professional chemists be given a professional standing in Navy service. Under present regulations the Navy is the only place in the United States where chemists are paid wages on a daily scale, and it is believed that they should be paid an annual salary, promoted to grades carrying titles to indicate their professional status, and, in general, be treated in a manner becoming to men who are professional and technical specialists. Dr. Parsons gave in some detail the training required and the custom elsewhere in recognizing the profession of chemistry. He stated that in view of the support which the Navy gave chemical research during the war and its appreciation of the work of chemists, it seemed incompatible for it to continue its present policy with respect to chemists. The editoi of THISJOURNAL followed with further statements along the same general lines. It is hoped that early action on condition. the part of the Board may change the present unsatisfactory
The University of Washington, Seattle, Wash., has announced the 27th annual winter mining session, to continue from January 4 to March 21, 1923. No previous training is required for entrance. The expenses of the courses consist of laboratory deposits for material actually used and a university fee of $20. The course in ceramics includes the study of clay-testing lime, plaster, cement, brick, stoneware, whiteware, refractories, glaze studies, clay technology, and terra cotta manufacture.
