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A1203 a n d CaO determined in four gram samples by substantially t h e same method of analysis a s t h a t employed in our previous work on t h e recovery of celite. T h e weights of t h e various constituents recovered were as follows:
t h a t respect now being chiefly in regard t o t h e accuracy with which determinations should be made. T h e form of reporting t h e result is, however, still a fruitful source of inconvenience a n d disagreement. T h e mineral constituents are variously reported in ionic form, in hypothetical combination, in oxide form, a n d in Sample Si02 A1203 FezOs CaO A . . . . . . . . . . . . . . 0 , 0 5 1 8 0.1377 0.0036 0.2704 equivalent of calcium carbonate. This divergence of B . . . . . . . . . . . . . .0.0515 0.1369 0.0038 0.2694 practice makes i t impossible t o compare t h e work of T h e s u m of these give t h e following percentage composi- t w o chemists without definite knowledge of their tion : methods of computation a n d laborious recalculation Si02 Ah03 Fez03 CaO of their results. Consequently, a n effort is being made 11.17 29.67 0.79 58.37 t o agree on a uniform manner of reporting results i n Calculating from this analysis t h e molecular ratios connection with t h e formulation of standard methods on t h e basis of I O O molecules of Rz03 (A1203 F e 2 0 3 ) for t h e analysis of water, now being conducted jointly we have 98.3 A1203, 1 . 7 Fe203, 62.8 3 0 2 , 352.4 CaO. b y committees of t h e American Chemical Society, If we subtract from t h e total CaO t h e a m o u n t theoret- t h e American Public Health Association, a n d t h e ically necessary t o form tricalcic silicate there would Association of Official Agricultural Chemists. This be left 164 molecules of CaO t o combine with I O O paper discusses t h e present confusing condition a n d molecules of R z 0 3 . These figures indicate almost t h e advantages of reporting t h e actual facts of analysis conclusively t h a t t h e fusible aluminate constituting in ionic form. t h e solvent in celite is t h e one described b y Shepherd, F A C T V E R S U S OPIlUION R a n k i n a n d Wright having t h e formula gCa0.3A12031 A s t a t e m e n t of a n analysis in hypothetical combinaa n d a melting point of about 1390’. tions is obviously a mixture of fact a n d opinion. T h e SUMMARY amounts of iron, calcium, sulfate, a n d other radicles T h e foregoing work confirms, in general, t h e hy- are determined b y various reactions; approximate pothesis “ T h a t celite consists essentially of a calcium separation of scaling from non-scaling constituents is aluminate, fusible a little above 1400’ a n d capable effected b y treatment with dilute alcohol; b u t further of dissolving, when liquid, calcium orthosilicate a n d t h a n this, ordinary chemical tests contribute little t o calcium oxide,” b u t we m a y now a d d t h a t t h e aluminate knowledge regarding t h e chemical composition of has t h e formula jCa0.3A1203 a n d t h a t if t h e concen- mineral waters, a n d consequently t h e exact amounts of tration of t h e calcium oxide, CaO, is sufficient a n d solu- t h e different salts in solution are largely conjectural. tion complete, pure tricalcic silicate will crystallize Though salts are probably present i t is a mathematical o u t on slow cooling. This also suggests a new theo- impossibility correctly t o apportion t h e bases among retical formula for Portland cement. t h e acids after having found only t h e amounts of t h e T h e Le Chatelier formula first proposed was acids a n d bases present. Y(3CaO.Al203). This called for X(3CaO.SiOz) COMMON F O R M S O F C O N B I N A T I O N t h e calcium oxide CaO, b y weight t o equal 2.8si02 As this lack of definite information gives free rein 1.6Al2O3. This always gives in practice a large excess t o t h e imagination there are m a n y opinions as t o how of free lime. T h e Newberry formula X(gCaO.SiOz) t h e bases a n d acids should be combined. Though Y(2CaO.Al203) calls for calcium oxide b y weight t o each method has ardent advocates, each is a personal 1.1.41~0~ b u t still cannot be adhered equal 2.8Si02 selection whose excellence can be proved only b y t o in practice without t h e cement carrying excess theory. I n order t o show t h e essential practical differfree lime. T h e formula which would be suggested ences in schemes of combination a n d some of t h e conb y t h e work above described would be X ( g C a 0 . S i 0 2 ) fusion t o which t h e y lead, t h e most common methods Y(gCa0.3A1203) which would call for calcium oxide have been applied t o t h e analysis of t h e water of o.gA1203. Such a formula hIissouri River shown in Table I. This chemical b y weight t o equal 2.8sio2 would conform more closely with t h e results obtained composition is not a t all exceptional, b u t i t has been in t h e best practice.
+
+
+ +
+
+
+
CHEMICALLABORATORY UNIVERSITY OF MICHIGAN ANN ARnoR
HYPOTHETICAL COMBINATIONS I N WATER ANALYSIS2 By R . B. DOLE? ISTRODUCTIOK
T h e procedures followed in determining t h e various mineral ingredients of natural waters have become fairly well standardized, t h e differences of opinion in A m . J . Sci., [55] 29 (1909), 293. Paper read before the Division of ll’ater, Sewage, and Sanitation at the 49th Meeting of the American Chemical Society, Cincinnati, April, 6-10, 1914. Published b y permission of t h e Director, United States Geological Survey. a Chemist, United States Geological Survey. 2
TABLEI-ANALYSIS
O F THE WATER OF MISSOURI RIVER NEAR RCEGG, Mo RESULTS IN P A R T S PER .MILLION Results of Reacting CONSTITUENTS analysis values .... 29.0 Silica (SiOz) . . . . . . . . . . . . . . . . . . . . . . . 0.0179 0.5 Iron ( F e ) . ......................... 2,5948 52.0 Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . 1.3136 Magnesium (Mg). . . . . . . . . . . . . . . . . . . 1 6 . 0 1,3454 31.0 Sodium (Pu’a). ..................... 0.1664 6.5 Potassium ( K ) . ..................... 0.0 0.0000 Carbonate radicle (‘203). . . . . . . . . . . . . 2.9192 Bicarbonate radicle (HCOs) . . . . . . . . . . 1 7 8 . 0 2.1632 Sulfate radicle ( S o d . . . . . . . . . . . . . . . . 104.0 0.0467 2.9 Nitrate radicle (N03). . . . . . . . . . . . . . . 12.0 0.3384 Chlorine (‘21). . . . . . . . . . . . . . . . . . . . . . .... Dissolved solids b y evaporation.. . . . . 3 4 6 . 0 5.4381 Total reacting value of basic radicles.. 5.4675 Total reacting value of acid radicles.. 0 . 2 7 per cent Error of closure of reacting v a l u e s . . . .
( a ) U ’S. Geol. Survey, W a f e r - S u p p l y P a p e v 236, 80.
purposely selected because i t represents a large group of waters in which carbonate is sufficient t o satisfy
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T H E J O r R N A L O F I L V D 1 7 S T R I d L d Y D E N G I S E E RI A’G C H E M I S T R Y
either calcium or magnesium b u t insufficient t o satisfy both. T h e first advantage of stating t h e actual facts of a n analysis is seen b y observing t h e reacting values or combining equivalents, which have been computed by multiplying t h e a m o u n t of each radicle b y its valence a n d dividing t h e product by its molecular weight. for they indicate t h a t t h e probable error of this analysis is about 0 . 3 per cent. K h e n hypothetical combinations are made, one of three procedures is usually followed: (I) A11 t h e bases a n d acids except t h e alkalies present in appreciable amount are estimated a n d t h e excess of acid is computed t o a n equivalent of sodium a n d potassium salts. ( 2 ) A11 t h e bases a n d acids except Carbonate are estimated a n d t h e excess of base computed t o an equivalent of carbonates. (3) A11 t h e bases a n d acids are determined a n d t h e figures representing 1:he salts are “doctored” t o balance. These practices effectually conceal errors of technique a n d leave it entirely t o t h e judgment of t h e analyst whether his error of closure is reasonable, a n d t h e evidence on which his judgment is based is completely masked because his hypothetical combinations show no error at all. On t h e other hand, t h e probable accuracy of t h e work can be calculated directly from t h e ionic statement as indicated in t h e table. Silica has not been included among either acids or bases. Some waters’ of unusual character m a y contain t h e silicate radicle, b u t i t is safe t o conclude t h a t i t is absent from most natural waters. Whether silica is a colloid depends on our definition of colloid, b u t whatever it may be called i t does not usually enter into t h e system of reactive bases a n d acids. This conclusion was reached se.iera1 years ago b y Kahlenberg a n d Lincoln,* a n d Kohlrausch3 a n d others make practically t h e same statement. Among 8,000 analyses of surface waters f r o m all parts of t h e United States the writer finds t h a t if silicate is not included t h e acid radicles are in excess in 40 per cent a n d t h e basic radicles in 6 0 per cent of t h e analyses a n d t h a t t h e difference either n-ay amounts t o only I or z parts per million, bears n o mathemat:cal relation t o t h e quantity or t h e proportion of silica, a n d m a y as reasonably be explained b y error of analysis as in a n y other way. This digression is inserted because i t has been proposed t o t h e committee t o include rules for compu.ting silica t o silicates of t h e various bases. Table I1 gives hypothetical combinations of t h e analytical d a t a in Table I . All t h e sets of combinations represent schemes used either b y a large number of analysts or by one or t w o concerns t h a t examine many samples from all parts of t h e country. T h e list might be much more extensive. N o extreme, b u t mathematically correct, schemes t h a t are unused have been introduced, (2nd the table has been further simpIified by omitting all b u t t h e more commonlymeasured constituents. The only difference between Columns I a n d z is t h a t sodium nitrate is calculated in Clarke, F. \T., C S . Geol. Survey, Bull. 491 (1911), 133. > J o u r . P h s s . Ciiem.. 2 (18981, ii. Z . P h y s i k . Chem.. 12 (1893), 7 7 3 . 1
711
one a n d potassium nitrate in t h e ot.her. I n Column 3, however, calcium is combined first with sulfate instead of carbonate. I n Column 4 , calcium is combined successively with sulfate, chlorine, a n d carbonate. Columns 6 a n d 7 represent methods used by certain boiler-water analysts, who ordinarily determine a n d TABLE11-HYPOTHETICALCOXBIXATIONS 1 29
Si02 Fe?Oa. . . . . . . . . . . . . .. Fe(HC0a)p. . . . . . . . 1.6 Ca(HC0a)z. . . . . . . . 210 CaSOl. . . . . . . . . . . . .. CaClz . . . . . . . . . . . . .. Ca(h’Od2, . . . . . . . . . .. Mg(HC0z)p . . . . . . . . 20 MgSOA.. . . . . . . . . . . 62 NaHC03.. . . . . . . . . hTazSOa.. . . . . . . . . . . 80 NaC1. . . . . . . . . . . . . LO h-aNOa.. . . . . . . . . . . 4 KC1 . . . . . . . . . . . . . . 12
KSOa.. . . . . . . . . . . . . .
_
S u m . . . . . . . . . . . . . 429 Scale-forming constituents,. , . . , . Foaming constitu e n t s . . ,. . . . . . .
REPRESENTING
(SEE TABLE I) 2 3 29 29
..
..
1.6 210
1.6 36
147
.. ..
..
..
..
94
..
80 13
10 4 12
..
-
9 5
-
..
-
1.6 126 68
8 147 19
..
..
4 96
96
1
..
is
.. .. -. .
..
-
I
29
0.7
2i0
68
..
..
..
96
..
24 60
83 20
83 20
.. ..
ii
-
I30
..
83 10
..
OX3 ANALYSIS
6 29 0,i
29
..
96
20 62
5
4 29 O.i
..
..
.. ..
..
430
430
428
430
42i
42i
233
233
255
257
236
235
236
106
107
80
82
105
103
103
report iron as t h e oxide a n d do not separate sodium a n d potassium b u t compute both together as sodium. ,4s these analysts would not determine nitrate in a water containing so little as t h a t under discussion absence of t h a t radicle has necessarily been assumed. Bicarbonates instead of carbonates also have been computed because analysis shows t h a t t h e carbonate radicle is absent; this slight deviation from t h e directed methods, however, makes n o difference in t h e theory a n d permits direct comparison with other schemes. According t o t h e scheme in Column j calcium nitrate, instead of potassium or sodium nitrate, is computed. According t o t h a t in Column 6 as much as possible of magnesium bicarbonate is computed first, while according t o t h a t in Column 7 as much as possible of calcium bicarbonate is computed first. T h e most obvious deduction from these figures is t h a t i t is impossible t o compare t h e report of one analyst with t h a t of another without recalculation. T h e next thought t h a t comes t o most of us is t h a t t h e other man’s scheme is incorrect. Some would object t o calculation of calcium nitrate a t t h e expense of calcium carbonate a n d some t o calculation of calcium chloride in t h e presence of sodium bicarbonate, while others would prefer t o calculate magnesium sulfate instead of calcium sulfate. Aside from t h e theoretical merits of t h e methods, consideration of which mould provoke endless discussion, there are these alarming facts: ( I ) All are widely-used methods of reporting t h e analysis of one water. ( 2 ) T h e results can not be directly compared with one another. (3) The results are used for estimating t h e quality of t h e water. ( 4 ) T h e results are given t o men who, not being chemists, are incompetent properly t o discount t h e statements b u t take t h e m a t their face value. One more digression may be permitted for t h e purpose of referring t o t h e sums of t h e computed constituents. The sums in t h e last half of t h e table are a little lower t h a n t h e others because nitrate a n d ferrous carbonate are disregarded. If these con-
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stituents had been computed all t h e sums would have been alike, t h e slight numerical differences among t h e m b‘eing due t o casting off decimals. Reference is made t o this agreement because some chemists, no doubt thoughtlessly, consider their methods of combination correct because t h e y “come out even.” One reports t h a t h e never has a n y acid or base left over, or very little, a n d another t h a t t h e sum of his calculated constituents agrees very closely with total solids b y evaporation. These comments prove t h e excellent technique of analysis b u t not t h e chemical correctness of t h e combinations. Reference t o t h e reacting values in t h e first table makes i t obvious t h a t , except by error of analysis, there can be no surplus of base or acid a n d t h a t t h e sums must agree, no matter how t h e radicles are combined or whether t h e combinations are logical. T h e disagreement between Column I , in which sodium nitrate is computed, a n d Column 2 , in which potassium nitrate is computed, causes several embarrassing numerical differences, a n d t h e layman unders t a n d s t h a t one analyst found saltpeter where t h e other did not. Though this difference may be practically unimportant some similar ones might lead t o serious misunderstanding. Whether t h e belief is well founded t h a t lithium is a very valuable ingredient of medicinal waters need not be discussed, b u t if i t is desired t o convey a n idea of t h e therapeutic effect of lithium t h e hypothetical combinations are likely t o mislead those who are not aware of t h e limitations of water analysis. If a water contains one p a r t per million of lithium one can compute 5.3 p a r t s of lithium carbonate, 6.1 p a r t s of lithium chloride, 7.9 parts of lithium sulfate, or 9.7 parts of lithium bicarbonate. If t h e water h a d t h e property of causing a n y physiologic reaction b y virtue of its content of lithium i t would exert t h a t property in proportion t o its content of t h e lithium radicle; yet b y expressing t h a t content as lithium bicarbonate instead of t h e carbonate t h e content of lithium salts has apparently been nearly doubled and in t h e mind of t h e spring owner a n d his clientele, for whom these compounds are computed, t h e therapeutic value of t h e analysis, if not of t h e water, has been doubled. I N T E R P R E TAT10 N 0 F R E S U LT S
I n t h e conventional methods of interpreting t h e various hypothetical combinations there is general agreement in some features a n d disagreement in others. Table I1 shows t h e estimates of scale-forming a n d nonincrusting or foaming constituents t h a t t h e analysts would report agree fairly well with one another, t h e numerical differences being too small t o cause essential difference in judging t h e value of t h e water. Corresponding estimates of t h e amounts of soda ash a n d lime t o soften t h e water would agree as closely as t h e sums of t h e constituents, because, although each analyst computes different constituents, he can not thereby change t h e amounts or relative proportions of t h e radicles with which t h e softening chemicals react. I n deciding whether t h e water would be corrosive there is greater diversity of opinion. The analysts whose combinations are reported in Columns 3 a n d 6 apparently would s t a t e t h a t t h e water is non-corrosive.
Vol. 6, NO. 9
The man whose method is shown in Column 5 would doubtless report t h e water t o be slightly corrosive, as he computes calcium nitrate. The calcium chloride indicated in Column 4 could hardly be considered corrosive in presence of so much sodium bicarbonate. I n t h e other three statements magnesium sulfate b u t n o t calcium sulfate is reported, a n d there is in them no apparent reason for stating whether t h e water is corrosive or non-corrosive. COMBINATIONS UNNECESSARY
Though hypothetical combinations are confusing m a n y chemists assert that and purely t h e y are necessary i n ascertaining t h e value of a water a n d in conveying a proper knowledge of t h e quality of t h e water. AS t o t h e reported insistence by t h e lay public so-called on hypothetical combinations t h a t can be understood it is pertinent t o inquire seriously how much a n y series of chemical figures means t o t h e layman a n d whether i t is not better t o report t h e basic facts for t h e information of t h e expert a n d t o add interpretations of t h e figures for t h e information of those who are unable t o make proper deductions for themselves. R a t h e r intimate experience for several years with lay comments on water analyses has made me extremely skeptical as t o how much of t h e t r u t h hypothetical combinations convey t o many men who are supposed t o make practical use of t h e results. W h a t t h e manufacturer or engineer wants t o know is how a particular water will fit some use t o which he wishes t o p u t it. Is i t safe t o drink? Does i t taste b a d ? Will it stain clothes? How much scale will i t form in boilers? How can it be softened? Answering these questions is t h e function of a n expert, who interprets t h e facts of analysis in t h e light of practical experience. It could be shown t h a t hypothetical combinations are not necessary for answering these questions, though t h e discussion will be confined t o interpretation in reference t o therapeutic value a n d quality for boiler use. MINERAL WATERS
Waters are analyzed more carefully a n d therefore more expensively for ascertaining their therapeutic value t h a n for a n y other purpose. Mineral salts t h a t cause definite physiologic reactions when drunk cause t h e reactions in relation t o t h e radicles t h a t are present. A solution of magnesium sulfate, for example, can be so dilute t h a t it has no perceptible taste. An equivalent concentration of sulfate in t h e form of ferrous sulfate has a distinct taste, a n d a solution of ferric chloride containing in t u r n a n equivalent concentration of iron has a similar taste, while again a n equivalent concentration of chloride as sodium chloride has no perceptible taste. T h a t is, in t h e iron solutions we taste t h e iron a n d not t h e sulfate or t h e chloride, a n d in order t o perceive the taste of t h e sulfate or t h e chloride radicle we must use a much stronger solution of a salt whose basic radicle is comparatively weak in its effect on the organs of taste. Twenty grams of magnesium sulfate has greater laxative action t h a n 20 grams of sodium sulfate because t h e magnesium ion also induces laxative action whereas
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t h e sodium ion does not, a s can be shown b y a n equivalent dose of sodium i n t h e form of sodium chloride. These rather crude illustrations serve t o indicate t h a t t h e physiologic action of a salt is caused b y one or more of t h e radicles composing t h e salt a n d is in proportion t o their concentration. T h e probable cathartic effect of a sulfate mater can therefore be measured b y its content of sulfate, computation of t h e possible mathematical proportions of sodium, potassium, magnesium, a n d calcium sulfates being unnecessary. T h e cathartic action of a water is increased b y its content of magnesium whether i t m a y be possible t o compute t h e magnesium as sulfate, chloride, or bicarbonate. As for t h e minor constituents of mineral waters, lithium, bromide, iodide, manganese, strontium, a n d t h e like, i t would not now be necessary to combat so m a n y fallacious ideas concerning their therapeutic value if serious consideration h a d heretofore been given t o t h e concentration of these radicles instead of t o t h e possible mathematical combinations i n which t h e y might be reported. BOILER
WATERS
713
foaming tendency he gets as good estimate of t h a t tendency b y multiplying sodium b y 2 . 7 as b y computing three different salts a n d adding t h e results together. Corrosion is considered partly a problem of reaction t h a t involves chiefly t h e setting free of acids b y precipitation of magnesium as t h e hydrate. T h a t corrosion m a y be caused wholly or partly by other conditions need not concern us in discussing t h e practical interpretation of this theory. Stabler’s formulas provide for t h e three possibilities. If there is not enough carbonate t o combine with all t h e magnesium some sulfate or chloride would be set free a n d t h e water would be corrosive; under such condition those who compute hypothetical combinations report magnesium sulfate or magnesium chloride, t h e former of which is classed as corrosive b y m a n y analysts a n d t h e latter universally as corrosive. If there is enough carbonate t o satisfy or more t h a n satisfy both calcium a n d magnesium t h e water probably is non-corrosive; under such condition i t is customary t o compute all t h e calcium a n d magnesium as carbonates, t o give t h e excess t o sodium, a n d t o class t h e water as non-corrosive. T h u s far boiler-water analysts agree in so far a s this theory of corrosion is accepted. If carbonate is sufficient t o combine with calcium or magnesium alone b u t n o t with both, corrosion might or might not occur. T h e latter condition is t h a t in t h e water under discussion, a n d t h e combinations in t h e second table show t h a t various analysts calculate diversely magnesium sulfate, calcium sulfate, a n d calcium nit r a t e , a n d disagree as t o whether corrosion would occur. T h e uncertainty of t h e corrosive action is quickly revealed b y Stabler’s formulas without recourse t o combinations. Corrosion occurs with waters t h a t would not be classed as corrosive b y a n y of these calculations, b u t t h a t is d u e t o other conditions a n d its probability is revealed b y computations of hypothetical combinations n o more t h a n b y consideration of t h e reaction of t h e radicles.
I n a very condensed article, H. Stabler’ has shown how t h e scale-forming constituents, t h e foaming constituents, t h e tendency toward corrosion, a n d t h e quantities of softening reagents can be computed directly from t h e radicles without recourse t o hypothetical combinations. Though i t h a s been. objected t h a t Stabler makes t h e same assumptions as are made i n combining t h e radicles as salts this is t r u e only in so far as his formulas are based on some of t h e currently accepted views of t h e reactions t h a t occur in boilers, concerning which much is yet t o be learned; a n d there remains t h e essenti.al difference t h a t b y use of his formulas n o theoretical salts, b u t t h e estimates t h a t are helpful t o t h e practical m a n , are obtained. Comparison of t h e figures at t h e ends of t h e preceding tables shows t h a t t h e estimate of scale directly from t h e radicles agrees closely with those based on comCOMBIEATIONS NOT ENDORSED binations. All unite in including silica, iron, a n d aluminum a s t h e oxides; whether there is silicate in Evidence of desire on t h e p a r t of chemists t o break t h e scale, as some have suggested, makes no arithmetical a w a y from conventional combinations of t h e condifference in t h e total. Magnesium carbonate a n d stituents found b y analysis is furnished b y t h e resolumagnesium sulfate are commonly included in total tions adopted b y various scientific organizations. As scale, though magnesium is precipitated mostly as t h e early as 1886 a committee appointed b y t h e Chemical h y d r a t e under high-pressure conditions a n d t h e oxide Society of Washington recommended1 t h a t all analyses better represents w h a t is f o u n d in t h e scale, as in of water should be s t a t e d in terms of t h e radicles found, Stabler’s formula. Some prefer t o compute t h e greatest whether elementary or combined, meaning evidently possible a m o u n t of calcium carbonate a n d some t h e expression of t h e immediate results of t h e analysis; greatest possible a m o u n t of calcium sulfate; calcium though this committee recommended t h a t t h e combinadoubtless is precipitated in both forms a n d a n average tions deemed most probable b y t h e chemists making between t h e m is struck in Stabler’s formula. t h e analyses should also be reported i t failed t o recomSimilarly a n average is struck among :he three mend a manner of combination, a n d i t is understood possible sodium salts in computing t h e foaming con- t h a t the reason for lack of such recommendation is stituents b y multiplying sodium b y 2.7. Other con- t h a t t h e members of t h e committee could not agree ditions besides t h e presence of a large a m o u n t of on one convention. sodium salts can cause foaming, a n d some believe t h a t T h e report of this committee was adopted2 b y foaming has no relation t o t h e concentration of t h e Section C of t h e American Association for t h e 9 d sodium salts. If. however, t h e interpreter of a n vancement of Science i n 1887, a n d 2 years later a comanalysis believes t h a t t h e sodium salts meisure t h e mittee of t h e British Sssociation for t h e Advancement
‘
E n s . Y e w s , 60 (19081, 3 5 5 ; also U. S. Geol. Survey, T a f e v - S u p p l y P a p e v , 274 (1911), 165.
1 2
Bull. Chem. SOC.Washington. C l e m . S e w s , 56 ( 1 8 8 i ) , 113.
S o . 2 (188:).
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of Science, while agreeing with t h e American Association in reporting t h e analytical d a t a obtained by direct determination, disapproved’ t h e statement of t h e mineral ingredients combined as salts unaccompanied by t h e original analytical d a t a . At t h e Fifth International Congress of Applied Chemistry2 t h e discussion of t w o papers on methods of expressing t h e results of water analyses indicated t h a t many of t h e chemists present favored t h e ionic form of, s t a t e m e n t , a n d a t t h e Sixth Congress, Christomanos3 recommended t h a t t h e simple statement of t h e acid a n d basic radicles in p a r t s per million be made in all water analyses. T h e methods of making hypothetical combinations in early editions of Fresenius’s “Quantitative Analysis” are accompanied b y t h e statement t h a t t h e y are general rules for which t h e analyst should exercise a latitude of selection.4 As Fresenius’s book represents t o a great extent a collective opinion it is interesting t o note t h a t a recent edition omits all rules for calculating combinations, calls attention t o t h e effect of solubility a n d mass action on affinity, t h e impossibility of comparing t h e reports of t w o analysts, a n d urges statement of t h e direct results.& A similar opinion is expressed in Tiemann-Gartner’s “ H a n d b u c h der Wasser.”G I n this country, Handy,’ McGill,8 Kimberleyg a n d several other well-known analysts have called attention t o t h e confusing state of reports of water analyses, a n d Clarke’O has a p t l y characterized hypothetical .combinations as “ a meaningless chaos of assumptions a n d uncertainties.” T h e figures of a hypothetically-combined water analysis express only t h e opinion of t h e man who made t h e m , a n d his opinion is not only different in some respects from those of his fellow analysts b u t is also likely t o change next year. Consequently, t h e statement conceals analytical facts incomparable with those concealed in other hypothetical statements, a n d interpretation of t h e d a t a of analysis is obscured b y t h e int,ervention of unnecessary combinations. I n view of these facts a n d t h e apparent disinclination of t h e organized chemical world t o approve a n y scheme of hypothetical combination, i t seems entirely advisable for American chemists not t o endorse a n y such convention, b u t t o recommend simple direct uncomplicated statement of t h e results of analysis in ionic form. U . S. GEOLOGICAL SURVEY WASHINGTON
CHEMISTRY OF THE BLEACHING O F COTTON CLOTH” BY
JOHN
C. HEBDEN
Cotton fiber appears under .the microscope a s a twisted ribbon, thicker a t the edges t h a n in t h e central area. The twisted structure gives i t t h e appearance of a spiral. The spirals, however, frequently are Chem. News, 60 (1889), 203. Ber. V . Inl. Kong. angew. Chem., 1 (1903). 261. Atli del V I Cong. I n l . d i Chimica Applicata, 7 ( 1 9 0 i ) , 213. 4 See 2d Am. ed., 1896, p . 674. 6 Cohn’s Translation of 6ln Cevinan ed., 2 (1904). 274. e Braunschweig (1895). 7 E n g . N e w , 51 (1904). 500. Bull. A m . RY. Enn. and Maintenance of W a y Assoc., 6 (1905), 612. B Jour. Infect. Diseases, S u p p l . , 1 (1905), 157. 10 U. S. Geol. Survey, Bull. 330 (1908), 54. Presented at the 6th Semi-annual Meeting of the American Institute of Chemical Engineers, Troy, New York, June 17-20, 1914. 1
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reversed, so t h a t there m a y be spirals turning t o t h e right a n d t o t h e left on one a n d t h e same fiber of cotton. T h e length of t h e fiber yaries from 2’/4 in. for t h e best Sea Island t o 3 / 4 in. for t h e lowest grade American cotton. T h e ratio of diameter t o length of staple If a single fiber ‘ varies from I : 1 3 j o t o I : z j o o . of low-grade American cotton mere increzsed t o a diameter of I in. a n d t h e length of t h e staple increased in proportion, t h e fiber would be more t h a n I O O feet long; while if a fiber of Sea Island cotton were increased in t h e same proportions, t h e length of this staple would be more t h a n zoo feet long. This extreme fineness, coupled with t h e twisted structure, makes cotton t h e vegetable fiber p a r excellence for spinning. COMPOSITION
OF COTTON F I B E R A N D COTTON CLOTH
The fiber is composed of a n outer layer or cuticle, a middle layer containing about 9 j per cent of t h e total fiber substance, a n d a wall bounding a central canal or lumen, with substances deposited in t h e lumen. The cuticle serves as a varnish or waterproofing t o protect t h e fiber, a n d is a mixture of fats, wax a n d carbohydrates, with some protein and mineral substances; t h e middle layer is nearly pure cellulose, while t h e wall of the central canal or lumen, a n d t h e compounds in t h e canal, are principally proteins mixed with small quantities of carbohydrates. T h e t o t a l substances not cellulose amount, on a n average, t o about j per cent of t h e fiber. When cotton is carded and spun, practically all of t h e adventitious impurities are removed. To facilitate t h e weaving, a sizing composed of starch, fats, soaps, a n d frequently protein substances. is added t o t h e warp yarn. The t o t a l additions in sizing t h e warp rarely exceed 5 per cent of t h e t o t a l weight of t h e fabric. Therefore, a s it comes from t h e loom, cotton cloth, calculated on t h e dry weight, will contain approximately 90 per cent cellulose, j per cent natural impurities consisting of carbohydrates, wax, f a t , protein a n d mineral substances, a n d j per cent of sizing material. COTTON C E L L U L O S E
Cellulose must be regarded as a definite zggregate of t h e products of plant life. It is a typical colloid. At t h e present s t a t e of knowledge it seems impossible t o fix a constitutional formula, or t o point t o a s definite reactions for cellulose or for cotton a s for bodies which t a k e t h e crystalline form: b u t from its reactions it is,possible t o obtain definite knowledge of its reactivity. T h e ease with which cellulose enters into definite combinations, as in t h e cuprammonium and in t h e x a n t h a t e or thiocarbonate reactions, a n d is in t u r n regenerated a s t r u e cellulose, shows t h e definite character of t h e aggregate a n d t h e similarity of its reactions t o those of other known colloids, a s for instance those of hemoglobin. Hemoglobin adds on a n a parts with oxygen a n d carbonic acid with ease, without apparently disturbing t h e power of t h e aggregate t o react, a n d without destroying t h e molecule. Many other illustrations might be cited t o show t h e definite character of the reactions of cellulose, a n d t h e similarity of these t o reactions of other known colloidal molecules or aggregates. Then again t h e cellulose aggregate may be disturbed
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