potentisation alters physico-chemical properties of water 2004

Jour nal of Ther mal Anal y sis and Cal o rim e try, Vol. 75 (2004) 815–836

NEW PHYSICO-CHEMICAL PROPERTIES OFEXTREMELY DILUTED AQUEOUS SOLUTIONS

V. Elia* and M. NiccoliDepartment of Chemistry, University ‘Federico II’ of Naples, Complesso Universitario di MonteS. Angelo, via Cintia 80126 Naples, Italy

(Received July 1, 2003; in revised form January 05, 2004)

Abstract

The ‘ex tremely di luted so lu tions’ are anom a lous so lu tions ob tained through the it er a tion of two pro -cesses: a di lu tion 1:100 in mass and a succussion. The it er a tion is re peated un til ex treme di lu tionsare reached (less than 1×10–5 mol kg–1) to the point that we may call the re sult ing so lu tion an ‘ex -tremely di luted so lu tion’, namely the com po si tion of the so lu tion is iden ti cal to that of the sol ventused (e.g. twice dis tilled wa ter). We con ducted ther mo dy namic and trans port mea sure ments of theso lu tions and of the in ter ac tion of those so lu tions with ac ids or bases. The pur pose of this study is toob tain in for ma tion about the in flu ence of suc ces sive di lu tions and succussions on the wa ter struc ture of the so lu tions un der study. We mea sured the heats of mix ing of acid or ba sic so lu tions with such‘ex tremely di luted so lu tions’, their elec tri cal con duc tiv ity and pH, com par ing with the anal o gousheats of mix ing, elec tri cal con duc tiv ity and pH of the sol vent. We found some rel e vant exo ther micex cess heats of mix ing, higher elec tri cal con duc tiv ity and pH than those of the un treated sol vent.The mea sure ments show a good cor re la tion be tween in de pend ent physico-chemical pa ram e ters.Care was taken to take into ac count the ef fect of chem i cal im pu ri ties de riv ing from the glass con -tain ers. Here we thus show that suc ces sive di lu tions and succussions can per ma nently al ter thephysico- chemical prop er ties of the wa ter sol vent. The na ture of the phe nom ena here de scribed stillre mains un ex plained, nev er the less some sig nif i cant ex per i men tal re sults were ob tained.

Key words:

Introduction

Since time im me mo rial wa ter has at tracted the sci en tists’ at ten tion. The stud ies car -ried out on this sys tem re vealed that this sub stance, de spite its ap par ent sim plic ity,be haves in a fas ci nat ing, of ten sur pris ing man ner. A num ber of ex pla na tions of thecom plex be hav iour of wa ter have been pub lished, many quite re cently. A large num -ber of mod els for wa ter have been de vel oped in an at tempts to dis cover the struc tureof wa ter [1], based on the prem ise that if the model can suc cess fully pre dict the phys -i cal prop er ties of wa ter then the struc ture of wa ter is de ter mined [2–4]. Re cent stud -

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* Author for correspondence: E-mail: [email protected]

ies on the physico-chemical prop er ties of wa ter put in ev i dence that the most stud iedliq uid by far, wa ter, still ex hib its to tally un ex pected prop er ties [5–12]. Rey [5] hasshown that even though they should be iden ti cal, the struc ture of hy dro gen bonds inpure wa ter is very dif fer ent from that of an ex tremely di luted so lu tion ob tained by anit er a tive pro ce dure of suc ces sive di lu tions and succusions. One could de duce fromthose stud ies that wa ter and aque ous so lu tions are com plex sys tems, ca pa ble of auto- organising them selves as a con se quence of lit tle per tur ba tions of var i ous na ture [13].Lobyshev and co-workers have shown that the ef fect of very low con cen tra tions andelec tro mag netic fields are long-scale re align ments of the struc ture of the liq uid,which can be of ei ther re vers ible or ir re vers ible [13]. Re cently, an im por tant pa percon cern ing the ef fect of di lu tion on mol e cules has been pub lished [14]. Samal andGeckeler have ob served that the clus ters size of fullerene-cyclodextrin, b-cyclo -dextrin, so dium chlo ride, so dium guanosine monophosphate, and a DNA oligo -nucleotide in creased with de creas ing con cen tra tion [14].

A note wor thy is sue is that of the hy po thet i cal ther a peu tic power of the ex tremelydi luted so lu tions of ho meo pathic med i cine that em ploys ‘med i cines with out mol e -cules’ that should thus ex hibit no heal ing prop er ties. Still, some times be hind ‘pop u larbe liefs’ lie ac tual phys i cal prop er ties, not yet fully in ves ti gated. The very ab sence ofmol e cules in the ac tive prin ci ple ob vi ously ex cludes the pos si bil ity of them tak ing partin any ac tion. Scant at ten tion has been paid to the sol vent, wa ter, the struc ture of whichis still sub ject to nu mer ous stud ies and not fully clar i fied yet. We thus reck oned rightand use ful to try and yield a sci en tific con tri bu tion to such is sue with out, how ever,touch ing the ther a peu tic as pects in any way, but re main ing strongly rooted in thephysico-chemical as pects. In pre ced ing pa pers [15, 16], we have re ported on the in ter -ac tion of the ‘ex tremely di luted so lu tions’ with ac ids or bases. The ‘ex tremely di lutedso lu tions’ were stud ied to test the va lid ity of the hy poth e sis that the par tic u lar prep a ra -tion tech nique and the ini tial pres ence of mol e cules of sol utes, of var i ous na ture, couldlead to an al ter ation of the ‘struc ture’ of the sol vent.

Our pres ent con tri bu tion con tin ues the pro gram aimed at un der stand ing theprop er ties of so lu tions that un der went the di lu tion and succussion cy cle. Here, we re -port a physico-chemical study that em ploys as tech niques: mix ing-flow micro -calorimetry, elec tri cal con duc tiv ity and potentiometry for pH mea sure ments.

Care was taken to ac count for im pu ri ties re leased by the glass con tain ers, thatcan af fect the mea sures of the physico-chemical pa ram e ters be cause of, re spec tively,the heat of neu tra li sa tion of al ka line bi car bon ates and silicic acid with the em ployedacid and ba sic reactives, the pres ence of elec tro lytes, bi car bon ates, and the pres enceof amphoteric elec tro lytes, bi car bon ates. So dium bi car bon ate and silicic acid can de -rive from the al ka line ox ides and sil ica in the glass of the con tain ers. The con cen tra -tion of so dium was de ter mined, through atomic absorbance mea sures, as well as thesilicic acid con cen tra tion, by mea sur ing the UV ab sorp tion of com plexes with am mo -nium molybdate.

The anal y ses we brought forth al lowed to con firm the dif fer ent physico- chemical be hav iour of the ‘ex tremely di luted so lu tions’ with re spect to that of un -treated, bidistilled wa ter at the same level of im pu rity. This ap proach also showed

J. Therm. Anal. Cal., 75, 2004

816 ELIA, NICCOLI: EXTREMELY DILUTED SOLUTIONS

that the pres ence of that kind of im pu ri ties is very im por tant in de ter min ing a dif fer -ent physico-chemical be hav iour af ter the prep a ra tion pro ce dure we de scribed. Be -cause of that, some ‘ex tremely di luted so lu tions’ were pre pared us ing as sol ventsome so lu tions with a low and known con tents of so dium bi car bon ate or silicic acid(5×10–5 M). This way the prob a bil ity to dif fer en ti ate be tween the physico-chemicalbe hav iour of the mixed un treated sol vent and that of the ‘ex tremely di luted so lu tions’ was greatly in creased.

It’s worth not ing that no work of this kind, con cern ing the study of the physico- chemical prop er ties of these ‘anom a lous so lu tions’, namely the ‘ex tremely di lutedso lu tions’, with sig nif i ca tive re sults, is known in cur rent lit er a ture. The ob servedphe nom e non pro vides new in for ma tion on the phys i cal na ture of the liq uid state ofwa ter and leads to con clude that the struc ture of the sol vent could be per ma nently al -tered by the pro ce dure used in pre par ing the so lu tions.

Experimental

Materials

The sol utes were Carlo Erba, Sigma or Fluka prod ucts, of the high est pu rity com mer -cially avail able. The so lu tions of the var i ous sol utes (NaOH, NaHCO3, SiO2) were pre -pared by mass us ing twice dis tilled wa ter. NaOH so lu tions were pro tected from thecon tact with at mo spheric car bon di ox ide by means of suit able traps. The ‘ex tremely di -luted so lu tions’ were pre pared us ing twice dis tilled wa ter or us ing as sol vent a so lu tionof so dium bi car bon ate or/and silicic acid at low an known con tent (5×10–5 mol L–1).

Procedures

The pro ce dure by which such ‘ex tremely di luted so lu tions’ are ob tained is the fol low ing[17]: the start ing point is a 1% in mass so lu tion; to pre pare, for ex am ple, the so diumchlo ride so lu tions (NaCl 3 CH to 12 CH), 1 g of NaCl is added to 99 g of wa ter. Af ter the me chan i cal treat ment, sim ple succussion, the so lu tion so ob tained is called ‘1 cen tes i malhahnemannian’ or 1 CH in short, and the name of the so lu tion starts with the name or for -mula of the sol ute or a sim ple ab bre vi a tion of it. So in the pre ced ing ex am ple, NaCl 1 CH is ob tained. The pro cess of succussion con sists in a vi o lent shak ing of the so lu tion bymeans of a me chan i cal ap pa ra tus, while the so lu tions are kept in ves sels of glass. In or der to pre pare the 2 cen tes i mal hahnemannian (NaCl 2 CH), 1 g of the 1 CH so lu tion isadded to 99 g of wa ter and the re sult ing so lu tion is succussed. This two pro cesses, di lu -tion 1:100 and succussion, are it er ated many times. The ap pa ra tus used in the succussionstep is a DYNA HV 1 by Debofar N.V.S.A. Bel gium. In a sin gle succussion pro cess 50ver ti cal strokes in 6 s are given to the ves sel con tain ing the so lu tion.

The same pro ce dure is used for the prep a ra tion of the ‘ex tremely di luted so lu -tions’ in NaHCO3 or H4SiO4 so lu tions. In this case, the sol vent em ployed for di lu tionis a so lu tion with known con tents of so dium bi car bon ate or silicic acid.


ELIA, NICCOLI: EXTREMELY DILUTED SOLUTIONS 817

Af ter their prep a ra tion, the ‘ex tremely di luted so lu tions’ and the sol vent usedfor pre par ing them (twice dis tilled wa ter; NaHCO3 or H4SiO4 in twice dis tilled wa ter) were stored at room tem per a ture. The sam ples and the sol vent were then tested at dif -fer ent ages, vary ing from sev eral days to sev eral months.

Sam ples of 4 dif fer ent sol utes were pre pared:NaCl: so dium chlo ride; GLP: n-(phosphonometil)-glycine; IAA: indole-3-acetic -

acid; 2,4-D dichlorophenoxicacetic acid.

Methods

Calorimetry

The heats of mix ing were mon i tored us ing a Ther mal Ac tiv ity Mon i tor (TAM)model 2227, by Ther mo met ric (Swe den) equipped with a flow mix ing ves sel. A P3peri stal tic pump from Pharmacia en voys the so lu tions into the cal o rim e ter throughTef lon tubes. The flow rates of the two liq uids are the same, and are con stant in thein let tubes, so that the so lu tion com ing out of the cal o rim e ter has a con cen tra tion halfthe ini tial one. The mass flow-rate, con stant within 1%, amounts to 3×10–3 g s–1: it was the same for all the ex per i ments.

The val ues of the mix ing enthalpies, DHmix, were ob tained us ing the fol low ingfor mula [18]:

DH m m m mQ

Pmix xi

yi

xf

yf

w

d

d( , )® =

t

where (dQ/dt) is the heat flux (W), Pw is the to tal mass flow-rate of the sol vent (kg s–1)and mx

i , myi and mx

f , myf , are the ini tial and fi nal molalities. DHmix is given in J kg–1 of

sol vent in the fi nal so lu tion.Mo lec u lar in ter ac tions can be stud ied through the anal y sis of the ex cess ther mo -

dy namic prop er ties, which are de fined as the dif fer ence be tween the val ues of thatfunc tion re ferred to a real and an ideal so lu tion. Ac cord ing to the treat ment of theprop er ties of so lu tions pro posed by McMillan–Mayer [19] and mod i fied by other au -thors [20–25], an ex cess ther mo dy namic prop erty, JE, of a so lu tion con tain ing n sol -utes, can be ex pressed as a virial ex pan sion of pairwise molalities and higher or derin ter ac tion co ef fi cients, j, as fol lows:

J jEik

k= 1

n

i = 1

n

= åå mi mk+higher order terms (1)

In the case of the ex cess enthalpy for bi nary and ter nary so lu tions, the virial co -ef fi cients can be eas ily ob tained from the di lu tion enthalpy, DdilH, which is re lated tothe cor re spond ing ex cess enthalpy, HE, as fol lows:

D dilE

xf

yf x

f

yf

Exi

yiH H m m

m

mH m m= -( , ...) ( , ...) (2)



where x, y,... are the sol utes, and mxf , mx

i and myf , my

i are the molalities of sol ute x andy af ter and be fore the di lu tion pro cess, re spec tively.

Thus the mix ing enthalpy of two bi nary so lu tions, due to the con tri bu tion of theheats of di lu tion of the two sol utes, x and y, and to the in ter ac tion of the two sol utes,can be ex pressed as fol lows:

DH h m m m h m m h m m mmix xx xf

xf

xi

xy xf

yf

yy yf

yf

yi= - + + -( ) ( )2 +higher order terms (3)

where hxx, hyy and hxy, the enthalpic in ter ac tion co ef fi cients, are ad just able pa ram e -ters.

The h co ef fi cients ap pear ing in Eq. (3) rep re sent the enthalpic con tri bu tions tothe Gibbs free en ergy co ef fi cients char ac ter is ing the in ter ac tion be tween pairs, trip -lets or higher or der in ter ac tions. They im plic itly ac count also for all vari a tions of sol -vent–sol vent and sol ute–sol vent in ter ac tions.

Their val ues fall in the range 1×102–1×104 (J kg mol–2). Con se quently, when thecon cen tra tion of sol ute y of an ‘ex tremely di luted so lu tion’ is less than 1×10–5 mol kg–1,while the con cen tra tion of sol ute x (NaOH) is 1×10–2 mol kg–1, the sole con tri bu tion inthe pre vi ous equa tion is that due to x, namely the heat of di lu tion of sol ute x.

It takes about three suc ces sive 1:100 di lu tions of the y so lu tion (3 CH) to reach a point where the y sol ute can not pro duce any sig nif i ca tive con tri bu tion to the heat ofmix ing and the pre vi ous equa tion re duces to:

DHmix=hxxmxf (mx

f –mxi )+higher or der terms

Based upon sta tis ti cal me chan ics con sid er ations, also Pitzer [26] adopted avirial ex pan sion of the terms in molality, with the sec ond co ef fi cient de pend ent uponionic strength. By mea sur ing the enthalpy of di lu tion it is thus pos si ble to ob tain thepairwise enthalpic in ter ac tion co ef fi cient for sol ute x. The in te gral yield ing this co ef -fi cient con tains, as fac tors, the po ten tial of mean force and the pairwise cor re la tionfunc tion, both av er aged over ev ery pos si ble ori en ta tion of the sol vent. In a sol ventwith a lo cal struc ture like wa ter, the po ten tial of mean force and the pairwise cor re la -tion func tion de pend on the dis tri bu tion of lo cal con fig u ra tions of the mol e cules inthe sol vent. Hence, by mea sur ing the DHmix in the mix ing of the so dium hy drox ideso lu tion with the ‘ex tremely di luted so lu tions’ it is pos si ble to ac quire in for ma tion on the sol vent through both sol ute–sol ute and sol ute–sol vent in ter ac tions.

pH measurements

Sys tem atic mea sures of pH were per formed on the ‘ex tremely di luted so lu tions’. pHpotentiometric data were col lected with a Crison pH ion me ter (model micropH 2002),with 0.1 mV or 0.001 pH units of res o lu tion for mea sure ments of volt age and pH, re -spec tively. A com bined glass elec trode (suit able for low ionic strength sys tems), con -tain ing 3 M KCl as the ref er ence elec tro lyte so lu tion, and an ex ter nal tem per a tureprobe were used. The asym met ri cal po ten tial and the Nernst slope of the com binedglass elec trode were de ter mined by cal i brat ing the elec trode daily with two Crisonstan dard buffer so lu tions of pH 4 and 7.



Conductivity measurements

Sys tem atic mea sures of elec tri cal con duc tiv ity (mS cm–1) were per formed on the ‘ex -tremely di luted so lu tions’. Con duc tiv ity data were col lected with a YSI con duc tiv ityin stru ment, model 3200, us ing a cell for low ionic strength sys tems (cell con -stant=0.1 cm–1). The cell con stant has been pe ri od i cally mea sured, us ing a KCl stan -dard so lu tion. The val ues of con duc tiv ity were tem per a ture cor rected to 25°C us ing a pre-stored tem per a ture com pen sa tion for pure wa ter [27].

Analytical determination of impurities

So dium con cen tra tion was de ter mined by the spec tro scopic method of atomic ab sorp -tion us ing a Spec tra A Varian in stru ment. Be fore mea sur ing the sam ples, a cal i bra tioncurve is nec es sary, ob tained us ing stan dard so lu tions. To pre pare the stan dard so lu -tions, NaCl has been dis solved in wa ter and di luted to 1 L to ob tain 1000 mg mL–1 Na.The work ing con di tions are [28]: lamp cur rent: 5 mA; fuel: acet y lene; sup port: air;flame stoichiometry: ox i diz ing. The used wave length de pends on the con cen tra tionrange of so dium. For our sam ples the wave length of 589.6 nm has been used. So diumis par tially ion ised in the air–acet y lene flame. To sup press the ion is ation, some po tas -sium chlo ride so lu tion has been added to pro duce a fi nal con cen tra tion of2000 mg mL–1 in all so lu tions, in clud ing the blank.

Sil i con is de ter mined as sil ica (SiO2) through a colorimetric method [29]. Am mo -nium molybdate at ap prox i mately pH 1.2, re acts with sil ica pres ent in so lu tion to pro -duce heteropolyacids, yel low col oured. The col our in ten sity is pro por tional to the con -cen tra tion of sil ica. This com plex is pho to met ri cally de ter mi na ble us ing a wave lengthof 410 nm. To de ter mine the con cen tra tion of sil ica a cal i bra tion curve is needed. Topre pare the stan dard so lu tions, so dium metasilicate nonahydrate, Na2SiO3×9H2O, hasbeen dis solved in wa ter and di luted to 1 L. Six stan dard so lu tions were pre pared, tocover the op ti mal range of con cen tra tion.

The con cen tra tions of im pu ri ties are of the or der of mag ni tude of sev eral ppm.

Results

The heats of mix ing with the sol vent as well as with the ‘ex tremely di luted so lu tions’, were de ter mined.

As re ported in pre ced ing pa pers [15, 16], we sought the con cen tra tion of the testsol ute (x) most suit able to put in ev i dence the ex is tence of the heat in ex cess in theex per i men tal con di tions. In creasing the con cen tra tion of NaOH so lu tions from 1×10–5

to 1×10–2 M, the de tected heat of mix ing in creases and then turns out to be con stantfor con cen tra tions of NaOH higher than about 5×10–3 M. There fore, to ob tain the larg -est ther mal ef fect, the most suit able con cen tra tion of NaOH is 1×10–2 M.

In about the to tal ity of the cases we found an ex cess exo ther mic heat of mix ing,in com par i son with the heat of mix ing that is ob tained when mix ing the same re -agents with twice dis tilled, un treated wa ter. By ex cess heat of mix ing, we sim ply



mean the fol low ing dif fer ence be tween ex per i men tal val ues: the heat of mix ing [J(kg of wa ter in the ini tial so lu tion)–1] of some re agent x with the ‘ex tremely di lutedso lu tions’, mi nus the heat of mix ing [J (kg of wa ter in the ini tial so lu tion)–1] of thesame re agent x mixed with un treated, twice dis tilled wa ter. In the case of a cal i bra tion curve (Figs 3–5) the same pro ce dure works, namely QE is the dif fer ence be tween theheat of mix ing of some re agent x with the so lu tions of NaHCO3 and/or H4SiO4 at thevar i ous con cen tra tions mi nus the heat of mix ing of the same re agent x mixed with the un treated twice dis tilled wa ter. In this way the con tri bu tion de riv ing by dis solvedCO2 was in stru men tally elim i nated.

In Ta bles 1–9, we re port: the ex per i men tal ex cess heats of mix ing of the stud ied‘ex tremely di luted so lu tions’ with NaOH 0.01 M (the ex per i men tal con di tions weresuch that the con cen tra tion of the NaOH so lu tion af ter the mix ing pro ce dure was halfthe ini tial one), the pH, the elec tri cal con duc tiv ity (mS cm–1), the con cen tra tion of so -dium and of SiO2 ex per i men tally de ter mined (see Method), for the ‘ex tremely di luteso lu tions’ ob tained us ing as sol vent: twice dis tilled wa ter, NaHCO3 or H4SiO4 so lu -tions 5×10–5 M in twice dis tilled wa ter.

In Ta bles 10 and 11 the ther mo dy namic and trans port pa ram e ters for NaHCO3

or H4SiO4 so lu tions used as stan dard so lu tions are re ported. Of those we mea suredthe heat of mix ing with NaOH 0.01 M, pH and elec tri cal con duc tiv ity that rep re sentthe cal i bra tion curves needed to cor rect for ‘chem i cal im pu ri ties’.

In Ta bles 12 and 13 are brought the ex cess heats of mix ing in func tion of the age of the sam ples pre pared us ing NaHCO3 or H4SiO4 so lu tions as sol vent. As it can beseen the QE for the sam ples in crease at in creas ing the age while that of the ref er encedo not. In the fol low ing Ta bles (14 and 15), the an a lyt i cal de ter mi na tion of the chem -i cal im pu ri ties is re ported. As the value of these im pu ri ties can be ob served it doesnot in crease to in crease some time.

In two prep a ra tions all the di lu tions, from 3 CH to 12 CH, are ‘in ac tive’: the mea -sured pa ram e ters are the same as with twice dis tilled wa ter (Ta bles 1 and 5). In the re -main ing eight prep a ra tions, the di lu tions be have as ‘ac tive’. For those ‘ex tremely di -luted so lu tions’ we take into ac count the con trib ute to the heat of mix ing de riv ing fromchem i cal im pu ri ties (the al ka line ox ides and sil ica in the glass of the con tain ers). Theval ues, once cor rected to ac count for chem i cal im pu ri ties, re sult sys tem at i cally higherthan those of the ref er ence sol vent. The ex cess heat of mix ing is of the same or der ofmag ni tude of the heat of di lu tion of the 0.01 M ba sic so lu tion that was used.

Thus, in 83% of the prep a ra tions the pro ce dure of suc ces sive di lu tions andsuccussions mod i fied the physico-chemical prop er ties of wa ter. In 50% of the sam -ples the heat is in ex cess; in 35% of the sam ples pH was higher and in 38% of thesam ples the elec tri cal con duc tiv ity was higher too.

Discussion

The heat of di lu tion of so dium hy drox ide, ex per i men tally mea sured, is exo ther mic.Ac cord ing to the McMillian and Mayer the ory, the sec ond co ef fi cient of the virial ofthe ex cess enthalpy for NaOH is greater than zero [19]. Thus, so dium hy drox ide be -





Ta ble 1 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of indole-3-acetic acid, IAA, at 25°C

System –QE,a,b pHcmS cm–1 c M

Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

IAA 4 CH 0 6.0 1.0

IAA 5 CH 0 6.0 1.1

IAA 6 CH 0 6.0 1.0

IAA 7 CH 0 6.0 1.1

IAA 8 CH 0 6.0 1.2

IAA 9 CH 0 6.0 1.0

IAA10 CH 0 6.1 1.0

IAA 11 CH 0 6.0 1.3

IAA12 CH 0 6.0 1.2

IAA 7 CH 0 5.9 1.1

IAA 8 CH 0 6.0 1.2

IAA 9 CH 0.7 6.3 2.4 6×10–6 N.D. N.D.

IAA 10 CH 0 5.8 1.1 N.D. N.D. N.D.

IAA 11 CH 1.4 6.4 6.5 1×10–5 1×10–5 N.D.

IAA12 CH 0 6.0 1.2 N.D. N.D. N.D.

Ta ble 2 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of so dium chlo ride, NaCl, at 25°C


Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

NaCl 4 CH 2.0 7.1 11.9

NaCl 5 CH 1.1 7.0 10.5

NaCl 6 CH 1.5 7.0 11.3

NaCl 7 CH 1.9 6.4 6.8 1×10–5 8×10–6 N.D.

NaCl 8 CH 1.6 6.3 6.7 1×10–5 6×10–6 N.D.

NaCl 9 CH 1.7 63 6.7 1×10–5 7×10–6 N.D.

NaCl 10 CH 2.0 6.4 6.5 2×10–5 9×10–6 N.D.

NaCl 11 CH 2.1 7.3 12.4

NaCl 12 CH 1.7 7.1 11.4aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equalto that in the blank solution, i.d. twice distilled water in polyethylene containers.

haves phenomenologically as a struc ture-maker sol ute. The ion–di pole in ter ac tionbe tween dis solved ions and wa ter mol e cules can af fect a num ber of bulk prop er ties of wa ter. The high elec tric fields ex erted by these ions can polar ise the wa ter mol e cules, pro duc ing ad di tional or der be yond the first hydration layer. The in tro duc tion of Na+

and OH– ions in so lu tion is ca pa ble of pro duc ing an ex ten sive per tur ba tion zone



Ta ble 3 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of 2,4-dichlorophenoxiacetic acid, 2,4-D, at 25°C


Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

2,4-D 3 CH 1.8 6.6 4.7 N.D. 2×10–5 N.D.

2,4-D 4 CH 2.1 6.7 5.3 N.D. 2×10–5 N.D.

2,4-D 5 CH 0 6.0 1.2 N.D. N.D. N.D.

2,4-D 6 CH 0.4 6.5 1.1 N.D. N.D. N.D.

2,4-D 7 CH 1.5 6.7 4.2 2×10–5 N.D. N.D.

2,4-D 8 CH 0.6 6.6 2.3 N.D. N.D. N.D.

2,4-D 9 CH 4.0 6.9 10.2 2×10–5 2×10–5 N.D.

2,4-D 10 CH 0 6.1 1.2 N.D. N.D. N.D.

2,4-D 11 CH 0 5.9 1.1 N.D. N.D. N.D.

2,4-D 12 CH 0.7 6.4 2.3 N.D. N.D. N.D.

Ta ble 4 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of so dium chlo ride, NaCl, at 25°C


Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

NaCl 4 CH 1.4 6.4 3.8 N.D. 1×10–5 N.D.

NaCl 5 CH 1.4 6.3 4.0 N.D. N.D. N.D.

NaCl 6 CH 0.4 6.1 2.1 N.D. N.D. N.D.

NaCl 7 CH 0 5.8 1.0 N.D. N.D. N.D.

NaCl 8 CH 0.5 6.1 2.1 N.D. N.D. N.D.

NaCl 9 CH 3.8 7.0 12.4 N.D. 4×10–5 N.D.

NaCl 10 CH 0 5.8 1.4 N.D. N.D. N.D.

NaCl 12 CH 0.4 6.0 2.7 N.D. N.D. N.D.aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equalto that in the blank solution, i.d. twice distilled water in polyethylene containers.

within the net of hy dro gen bonds of wa ter, in ac cor dance with the o ret i cal stud ies thatem ploy ab in itio com pu ta tional tech niques [30].

As men tioned in the Re sults sec tion, when mix ing the ‘ex tremely di luted so lu -tions’ with aque ous so lu tions of so dium hy drox ide 0.01 M, the mea sures re veal anex cess heat of mix ing. Ev ery ex per i men tally mea sured ex cess heats turned out to beexo ther mic. Re mem bering that the ‘ex tremely di luted so lu tions’ have the same com -po si tion of pure wa ter or of ref er ence sol vent, the pairwise enthalpic in ter ac tion co ef -fi cient of NaOH in the ‘ex tremely di luted so lu tions’ could be higher than that of thesol vent. In the di lu tion pro cess an in crease of the av er age num ber of wa ter mol e culesof hydration ac counts for the exo ther mic ef fect in this pro cess [31].



Ta ble 5 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of indole-3-acetic acid, IAA, at 25°C


Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

IAA 3 CH 0 5.9 1.0 N.D. N.D. N.D.

IAA 4 CH 0 6.0 1.1 N.D. N.D. N.D.

IAA 5 CH 0 6.0 1.0 N.D. N.D. N.D.

IAA 6 CH 0 6.0 1.0 N.D. N.D. N.D.

IAA 7 CH 0 5.9 1.0 N.D. N.D. N.D.

IAA 8 CH 0 5.9 1.0 N.D. N.D. N.D.

IAA 9 CH 0 6.0 1.0 N.D. N.D. N.D.

IAA 10 CH 0 5.9 1.0 N.D. N.D. N.D.

IAA 11 CH 0 6.0 1.0 N.D. N.D. N.D.

IAA 12 CH 0 5.9 1.1 N.D. N.D. N.D.

IAA 4 CH 0 5.9 1.1 N.D. N.D. N.D.

IAA 5 CH 1.4 6.7 4.3 7×10–6 7×10–6 1×10–5

IAA 6 CH 1.2 6.7 4.1 5×10–6 8×10–6 1×10–5

IAA 7 CH 0.4 6.5 2.2 N.D. N.D. N.D.

IAA 8 CH 0.3 6.2 1.2 N.D. N.D. 5×10–6

IAA 9 CH 4.9 7.1 12.8 N.D. 4×10–5 N.D.

IAA 10 CH 0.2 6.0 1.2 N.D. N.D. N.D.

IAA 11 CH 0.3 6.0 1.6 N.D. N.D. N.D.

IAA 12 CH 0.2 6.0 1.4 N.D. N.D. N.D.aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equalto that in the blank solution, i.d. twice distilled water in polyethylene containers.



Ta ble 6 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of n-(phosphonimetil)-glycine, GLP, at 25°C


Na+ MCa 2+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – – –

GLP 4 CH 0.2 6.0 1.1 N.D. N.D. N.D.

GLP 5 CH 0.3 6.0 1.6 N.D. N.D. N.D.

GLP 6 CH 0.2 6.0 1.2 N.D. N.D. N.D.

GLP 7 CH 0.8 6.1 2.8 N.D. 8×10–6 N.D.

GLP 8 CH 0.1 5.9 1.2 N.D. N.D. N.D.

GLP 9 CH 3.2 7.0 8.4 2×10–5 2×10–5 N.D.

GLP 10 CH 0.2 6.0 1.2 N.D. N.D. N.D.

GLP 12 CH 1.7 6.4 4.5 9×10–6 1×10–5 N.D.

Ta ble 7 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex tremelydi luted so lu tions of 2,4-dichlorophenoxiacetic acid, 2,4-D, in NaHCO3 5×10–5M as sol vent


Na+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – –

Ref [1] 1.9 6.8 5.3 4.8×10–5 N.D.

Ref [2] 1.9 6.8 5.3 4.9×10–5 N.D.

Ref [3] 1.9 6.8 5.3 4.7×10–5 N.D.

Ref [4] 1.9 6.8 5.4 4.7×10–5 N.D.

2,4-D 4 CH 2.1 6.8 5.2 4.8×10–5 N.D.

2,4-D 5 CH 2.1 6.9 5.2 4.8×10–5 N.D.

2,4-D 6 CH 2.0 7.1 5.3 4.8×10–5 N.D.

2,4-D 7 CH 2.0 7.0 5.3 4.7×10–5 N.D.

2,4-D 8 CH 2.0 6.9 5.3 4.7×10–5 N.D.

2,4-D 9 CH 2.8 7.1 5.3 4.7×10–5 N.D.

2,4-D 10 CH 1.9 6.8 5.2 4.7×10–5 N.D.

2,4-D 11 CH 2.3 6.8 5.4 4.7×10–5 N.D.

2,4-D 12 CH 1.9 6.8 5.3 4.7×10–5 N.D.

aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equalto that in the blank solution, i.d. twice distilled water in polyethylene containers.

The ‘ex tremely di luted so lu tions’ be hav iour sug gests that the ex cess heat ofmix ing is linked to an in crease in the num ber and/or en ergy of the hy dro gen bonds inthe ex am ined sys tems, with re spect to the ref er ence sol vent. Dur ing the mix ing withthe ‘ex tremely di luted so lu tion’, the Na+ and OH– ions would more ef fi ciently hy -drate than in wa ter, ex ploit ing, prob a bly, the ag gre gates of wa ter mol e cules found inthe sol vent, with a con se quent in crease of the pairwise enthalpic in ter ac tion co ef fi -cient and pro duc ing an exo ther mic ex cess heat.

Mixing with strong ac ids or bases seems to be a nec es sary con di tion in or der todif fer en ti ate be tween the ca lo ri met ric be hav iour of the so lu tion un der study and theref er ence sol vent. The sug ges tive hy poth e sis that H+ and OH– ions, char ac ter is ing ac -ids and bases, and wa ter are a nec es sary con di tion for ob tain ing the heats in ex cess, is not to be ex cluded.

Ev ery sam ple of a prep a ra tion turns out to be char ac ter ised by dif fer ent fac tors,linked to the prep a ra tion tech nique as well as with the stor age con di tions. The main pa -ram e ters that char ac ter ise the ‘ex tremely di luted so lu tions’ we em ployed in this workare:

· Na ture of sol ute



Ta ble 8 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of 2,4-dichlorophenoxiacetic acid, 2,4-D, in H4SiO4 1×10–5Mas sol vent


Na+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – –

Ref [1] 0.4 5.9 1.0 N.D. 1×10–5

Ref [2] 0.4 6.1 1.0 N.D. 1×10–5

Ref [3] 0.5 6.1 2.3 N.D. 1×10–5

Ref [4] 0.4 5.9 1.0 N.D. 1×10–5

2,4-D 4 CH 0.4 5.9 1.0 N.D. 1×10–5

2,4-D 5 CH 0.4 6.0 1.0 N.D. 1×10–5

2,4-D 6 CH 7.2 6.2 1.8 5×10–6 4×10–5

2,4-D 7 CH 0.4 6.1 1.0 N.D. 1×10–5

2,4-D 8 CH 0.4 6.1 1.0 N.D. 1×10–5

2,4-D 9 CH 0.6 6.2 1.1 N.D. 1×10–5

2,4-D 10 CH 0.4 6.0 1.0 N.D. 1×10–5

2,4-D 11 CH 0.5 6.1 1.0 N.D. 1×10–5

2,4-D 12 CH 0.4 6.1 1.0 N.D. 1×10–5

aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equal

· De gree of di lu tion· Num ber of strokes and fre quency dur ing succussion· Age of sam ples· The na ture of the con tain ers, em ployed in both prep a ra tion and stor age, can be

con sid ered an ad di tional fac tor, be cause of the na ture and quan tity im pu ri ties they re -lease.

Each of those fac tors in flu ences the ‘ex tremely di luted so lu tions’ in dif fer entways and amount.

When an ‘ex tremely di luted so lu tions’ is tested at dif fer ent times (that’s to saydif fer ent por tions of a sin gle sam ple are em ployed in dif fer ent ex per i men tal mea -sures) the ex cess heat turns out to be larger as the age of the sam ple grows, with in -creases of more that 100%. This tem po ral evo lu tion can be slow, re quir ing monthssince the prep a ra tion. As Figs 1 and 2 show, the vary ing value of the ther mo dy namicpa ram e ters as a func tion of time is a fea ture of the ‘ex tremely di luted so lu tions’ only,those that un der went the succussion–di lu tion cy cle, and is not de tected in the ref er -ences (Ta bles 12 and 13). For the sam ples re ported in graphic, the an a lyt i cal de ter mi -



Ta ble 9 Ther mo dy namic and trans port prop er ties and im pu ri ties con tents (mol L–1) for ex -tremely di luted so lu tions of 2,4-dichlorophenoxiacetic acid, 2,4-D, in H4SiO4 5×10–5Mas sol vent


Na+ M SiO 2

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1 – –

Ref [1] 1.5 5.9 1.0 N.D. 5×10–5

Ref [2] 1.5 6.1 1.0 N.D. 5×10–5

Ref [3] 1.5 6.1 1.3 N.D. 5×10–5

Ref [4] 1.5 5.9 1.0 N.D. 6×10–5

2,4-D 4 CH 1.5 5.9 1.0 N.D. 5×10–5

2,4-D 5 CH 1.9 6.0 1.0 N.D. 5×10–5

2,4-D 6 CH 2.7 6.0 1.5 5×10–6 6×10–5

2,4-D 7 CH 1.6 6.1 1.0 N.D. 5×10–5

2,4-D 8 CH 1.5 6.1 1.0 N.D. 5×10–5

2,4-D 9 CH 1.8 6.2 1.1 N.D. 6×10–5

2,4-D 10 CH 1.5 6.0 1.0 N.D. 5×10–5

2,4-D 11 CH 1.5 6.1 1.0 N.D. 5×10–5

2,4-D 12 CH 1.5 6.1 1.0 N.D. 5×10–5

aExcess heat of mixing, in J (kg of solvent in initial solution)–1. bAverage and standard deviationdetermined using 60 experimental heats of mixing of NaOH 0.01 M with water. cAverage andstandard deviation determined using 60 experimental measurement of water. The error in thedetermination of Na+, Ca2+ and SiO2 is 5×10–6 mol L–1. N.D. – not detected. The value of concentration is below the detection limit of apparatus employed. Namely, the concentration in the solution is equal



Ta ble 10 Ther mo dy namic and trans port prop er ties for so lu tions of so dium bi car bon ate,NaHCO3, at 25°C

System –QE,a,b pHcmS cm–1 c

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1

NaHCO3 1.0×10–5 0.3±0.1 6.0±0.2 1.6±0.2

NaHCO3 1.5×10–5– 6.2±0.2 2.0±0.2

NaHCO3 2.0×10–5– 6.3±0.2 2.5±0.2

NaHCO3 2.5×10–5– 6.4±0.2 2.8±0.2

NaHCO3 3.0×10–5– 6.4±0.2 3.2±0.2

NaHCO3 3.5×10–5– 6.5±0.2 3.5±0.2

NaHCO3 4.0×10–5– 6.5±0.2 4.1±0.2

NaHCO3 4.5×10–5– 6.6±0.2 4.6±0.2

NaHCO3 5.0×10–5 1.7±0.1 6.7±0.2 5.0±0.2

NaHCO3 6.0×10–5– 6.7±0.2 6.1±0.2

NaHCO3 7.0×10–5– 6.7±0.2 6.9±0.2

NaHCO3 8.0×10–5– 6.8±0.2 7.9±0.2

NaHCO3 1.0×10–4 1.7±0.1 6.9±0.2 9.8±0.2

NaHCO3 2.5×10–411.1±0.1 7.5±0.2 24.1±0.2

NaHCO3 5.0×10–420.4±0.1 7.7±0.2 47.1±0.2

NaHCO3 7.5×10–430.6±0.1 7.9±0.2 71.6±0.2

NaHCO3 1.0×10–340.7±0.1 8.1±0.2 93.6±0.2

aExcess heat of neutralisation (J kg–1) in the titration of NaHCO3 solutions with sodium hydroxide.bAverage and standard deviation determined using 60 experimental heats of mixing of NaOH 0.01 Mwith water. cAverage and standard deviation determined using 60 experimental measurement of water.

Ta ble 11 Ther mo dy namic and trans port prop er ties for so lu tions of silicic acid, H4SiO4, at 25°C

System –QE,a,b pHcmS cm–1 c

H2O bid. 2.1±0.1 5.8±0.2 1.2±0.1

H4SiO4 1.9×10–358.4±0.1 5.8±0.2 1.1±0.1

H4SiO4 9.6×10–429.7±0.1 5.8±0.2 1.2±0.1

H4SiO4 5.1×10–414.5±0.1 5.9±0.2 1.2±0.1

H4SiO4 2.7×10–4 7.2±0.1 5.9±0.2 1.1±0.1

H4SiO4 1.2×10–4 3.6±0.1 5.8±0.2 1.0±0.1

aExcess heat of neutralisation (J kg–1) in the titration of H4SiO4 solutions with sodium hydroxide.bAverage and standard deviation determined using 60 experimental heats of mixing of NaOH 0.01 Mwith water. cAverage and standard deviation determined using 60 experimental measurement of water.



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.

na tion of im pu ri ties has been ef fected in func tion of the age. This anal y sis has not un -der lined an in crease of the con tent of chem i cal im pu ri ties.

We ex am ined the na ture of the ini tially pres ent sol ute and the di lu tion de gree.We ob tained ‘ex tremely di luted so lu tions’ orig i nat ing from dif fer ent sol utes and with di lu tion rang ing from 4 CH to 12 CH. A cor re la tion be tween those two fac tors, ini tial sol ute and di lu tion, and the ther mo dy namic be hav iour is not yet sug gested by ourdata as a whole. It is note wor thy that those so lu tions that un der went the di lu tion cy -cle, but not the succussion one, do not dif fer from the ref er ence sol vent. It must beun der lined that the it er a tive pro ce dure of di lu tions and suc ces sions works also in theab sence of the ini tial sol ute. The succussion phe nom e non thus ap pears as fun da men -tal in or der to ac ti vate the dif fer ent be hav iour of the ‘ex tremely di luted so lu tions’.



Fig. 1 Ex cess heats of mix ing of ‘ex tremely di luted so lu tions’ di lute so lu tions vs. theage of the sam ples. Prep a ra tion of 2,4-dichlorophenoxiacetic acid inNaHCO3 5×10–5 M as sol vent

Fig. 2 Ex cess heats of mix ing of ‘ex tremely di luted so lu tions’ di lute so lu tions vs. theage of the sam ples. Prep a ra tion of 2,4-dichlorophenoxiacetic acid inH4SiO4 5×10–5 M as sol vent

Since the con tain ers em ployed to pre pare and store the ‘ex tremely di luted so lu -tions’ are made of glass, we per formed mea sures of atomic absorbance to de ter minethe re leased quan tity of so dium ox ide, ap pear ing as bi car bon ate in so lu tion, as wellas spectrophotometic mea sures (UV-VIS) to de ter mine the pres ence of sil ica un derthe form of undissociated silicic acid. So lu tions of so dium bi car bon ate and silicicacid in known quan ti ties were pre pared, to pro duce the cal i bra tion curves needed tocom pen sate for chem i cal im pu ri ties in the ‘ex tremely di luted so lu tions’.

The ob tained data put in ev i dence a dif fer ing be hav iour, with re spect to the ref -er ence wa ter with the same amount of im pu ri ties, when grad u ally in creas ing the con -cen tra tion of im pu ri ties as shown in Figs 3–5. For the ‘ex tremely di luted so lu tions’the ex per i men tally ob tained val ues dif fer from that at trib ut able to the sole im pu ri ties; those so lu tions ex hibit a dif fer ent physico-chemical pic ture to that of the ref er encesol vent, as can be seen in Ta bles 10 and 11.

Such re sults seem to sug gest that sub stances re leased by the glass of the con tain -ers, found as traces, are able to ‘ac ti vate’ the ‘ex tremely di luted so lu tions’ in thesense that they ex hibit a dif fer ent ther mo dy namic pic ture from that of the sol vent, the chem i cal com po si tion of which is iden ti cal. A pos si ble in ter pre ta tion of the phe nom -e non is that those sub stances al low the sol vent, prob a bly due to the succussion pro -cess, to ac quire a var ied struc tural or gani sa tion. By con trol ling ev ery pa ram e ter af -fect ing a prep a ra tion maybe it will be pos si ble in the fu ture to better the qual i ta tiveand/or quan ti ta tive reproducibility of the phe nom e non un der ex am i na tion.



Fig. 3 Com par i son be tween the ex per i men tally mea sured ex cess heats and the com -puted ones. � – ex per i men tally mea sured, p – com puted tak ing into ac count the ex per i men tally mea sured con tents of so dium, cal cium and silicic acid. In thisfig ure we re port the QE of all sam ples stud ied with out tak ing into ac count thena ture of the sol utes nor the de gree of di lu tion. The dif fer ence be tween the val -ues of QE of the sam ples and those of the cal i bra tion curve, that takes into ac -count the chem i cal con tri bu tion due to the an a lyt i cally de ter mined im pu ri ties, is at trib ut able to the new phe nom e non



Fig. 4 Com par i son be tween the ex per i men tally mea sured pH val ues and the cal i bra tioncurve. � – ex per i men tally mea sured, p – mea sured for so lu tions of NaHCO3 atknown con tent. In this case the con tri bu tion the H4SiO4 is not in flu ent be cause thevery low de gree of dis so ci a tion. In this fig ure we re port the pH of all sam ples stud -ied with out tak ing into ac count the na ture of the sol ute nor the de gree of di lu tion.The dif fer ence be tween the val ues of pH of the sam ples and those of the cal i bra -tion curve, that takes into ac count the chem i cal con tri bu tion due to the an a lyt i cally de ter mined im pu ri ties, is at trib ut able to the new phe nom e non

Fig. 5 Com par i son be tween the ex per i men tally mea sured elec tri cal con duc tiv ity val uesand the com puted ones. � – ex per i men tally mea sured, p – mea sured for so lu -tions of NaHCO3 at known con tent. In this fig ure we re port the elec tri cal con duc -tiv ity of all sam ples stud ied with out tak ing into ac count the na ture of the sol utenor the de gree of di lu tion. The dif fer ence be tween the val ues of the elec tri calcon duc tiv ity of the sam ples and those of the cal i bra tion curve, that takes into ac -count the chem i cal con tri bu tion due to the an a lyt i cally de ter mined im pu ri ties, isat trib ut able to the new phe nom e non

The ther mo dy namic pic ture of the ‘ex tremely di luted so lu tions’ has been madeeven richer by pH and elec tri cal con duc tiv ity mea sures.

pH mea sures re veal a sta tis ti cally higher value than that of the ref er ence sol ventwith the same de gree of im pu ri ties com ing from the glass of the con tain ers. The dif -fer ence be tween the mea sured value and that cal cu lated ac cord ing to the con tents ofim pu ri ties has been at trib uted also to a vari a tion of the ac tiv ity of the sol vent, prob a -bly due to a dif fer ent struc tural or gani sa tion of the sol vent it self. To con firm the hy -poth e sis of a vari a tion of ac tiv ity of the sol vent, caused by struc tural vari a tions, mea -sures of e.m.f. in suit able gal vanic cells are planned, to es ti mate the vari a tion of ac -tiv ity of a sol ute (NaCl, NaClO4) dis solved in it in ponderal quan ti ties. This wouldput in ev i dence the vari a tion of ac tiv ity in the sol vent that has un der gone the di lu -tions and succussions pro ce dure.

Elec tri cal con duc tiv ity mea sures were per formed on the stud ied sam ples,at 25°C. Such mea sures put in ev i dence a sys tem atic higher value of the spe cific con -duc tiv ity with re spect to that of the sol vent. In this case too our dis cus sion of the ‘ex -tremely di luted so lu tions’ be hav iour keeps track of so dium bi car bon ate, the amountof which is de ter mined through atomic absorbance. The pres ence of bi car bon atealone can not ex plain the in crease in elec tri cal con duc tiv ity for the sam ples, with re -spect to the sol vent at an equal con cen tra tion of ‘chem i cal im pu ri ties’, just like itcould not ex plain the whole ex cess heat found in pH mea sures.

For the so lu tions un der study, mea sures of ex cess heat and elec tri cal con duc tiv -ity turn out to be cor re lated, point ing at a pre sum ably sin gle cause of the ex hib itedbe hav iour. In wa ter the high mo bil ity of H+ and OH– ions un der a gra di ent of elec tri -cal po ten tial is ex plained through the hop ping mech a nism as pro posed by Grotthus[32]. The mi gra tion of ions re sults strongly as so ci ated to clus ters of wa ter mol e culesthrough hy dro gen bonds. Thus an higher struc tur ing of the sol vent could fa vour theafore men tioned mech a nism, lead ing to an higher value for the con duc tiv ity in the‘ex tremely di luted so lu tions’ and ex plain ing the cor re la tion with the heat in ex cess.

Conclusions

The ther mo dy namic pic ture here pre sented al lows to make the hy poth e sis that thepro ce dure of di lu tions and succussions, even if there are no con vinc ing the o ret i calex pla na tions yet, is ca pa ble of mod i fy ing in a per ma nent way the physico-chemicalfea tures of wa ter. There is no doubt that, from a strictly chem i cal point of view, the‘ex tremely di luted so lu tions’ are ex actly iden ti cal to the sol vent em ployed in theirprep a ra tion: twice dis tilled wa ter, with a cer tain amount of chem i cal im pu ri ties de -riv ing from the dis so lu tion of mod est quan ti ties of al ka line ox ides and sil ica from theglass con tain ers. Even when ac count ing for the con tri bu tions to the stud ied pa ram e -ters that come from the lat ter sub stances, the con clu sion is that the be hav iour of the‘ex tremely di luted so lu tions’ is mea sur ably dif fer ent from that of the con trol so lu -tions. What’s more, a re ally in trigu ing phe nom e non is that of the evo lu tion of somephysico-chemical pa ram e ters with time, that hints at the hy poth e sis of a trig ger ef fect on the for ma tion of mo lec u lar ag gre gates, fol low ing the succussion pro ce dure, a not



eas ily re pro duc ible ef fect, but one that once es tab lished would per mit a slow grow ing of the ther mo dy namic pa ram e ters, prob a bly fol low ing the in crease of the num ber ofag gre gates or of their size or of both.

Hence, a nec es sary con di tion to be able to ex per i men tally as cer tain vari a tions of the ther mo dy namic prop er ties of such di lu tions is the pres ence of struc tural vari a -tions in the sol vent, via wa ter mol e cules ag gre gates, in num ber and size suit able to be re vealed by a ther mo dy namic tech nique. The lat ter fact could be one of the causes ofso many fail ures in this re search field, fail ures that con jure in keep ing it too ‘mys te ri -ous’ still. It is how ever our hope that the frame out lined in this and in the two pre ced -ing works [15, 16], will elicit enough sci en tific con cern as to in duce other re searchesto re peat this kind of ex per i ments. Should those rep e ti tions yield pos i tive re sults,then our mod els of wa ter will prob a bly have to be re vised in or der to ac count forthese lat est ex per i men tal re sults.

* * *

We thank Dr. Luca Elia for help ful sug ges tions, dis cus sions and re fine ments of Eng lish.

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