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Old 23rd August 2007, 05:16 AM   #182
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Here is the first draft of the proposed letter. Constructive criticism please.

Dear Sir,

We wish to draw to your attention serious anomalies and incongruities in the UV absorption data presented in the paper by Rao et al., published in your August 2007 issue [1].

In a study of this nature, which in effect is examining multiple samples of ethanol, the over-riding concern must be absolute uniformity in the source of the solvent. For the data to be valid, it is essential that every drop of ethanol used must be sourced from the same stock bottle. However, the authors fail to make any mention of this point, and it is clear from the results presented that the source of ethanol was most certainly not uniform.

The most striking anomaly is the UV spectrum presented for “plain ethanol”, a single trace repeated three times in figure 3. The provenance of this sample is not recorded in the paper. This trace reveals extremely high absorbance (greater than 0.8 absorbance units) at 250nm, falling off steeply towards 400nm but still above 0.4 units by 350nm, and demonstrating an absorbance peak of 0.65 units with a l max of about 330nm. It is simply impossible to represent this trace as being ethanol of any recognised degree of purity. Spectroscopic grade ethanol has an absorbance of less than 0.05 units between 250 and 400nm [2], and even USP/NF pharmaceutical grade ethanol has an absorbance of less than 0.3 units at 250nm, falling off to less than 0.1 units by 270nm [3]. If the substance measured by the authors as “plain ethanol” was indeed ethanol at all, it is clear that it contained extremely high levels of impurities, possibly including acetone.

In contrast, the spectra of the samples which were diluted and succussed (Nat mur, Nux vomica and the “succussed ethanol” with no mother tincture), and which were presumably all supplied by Hahnemann Laboratories as detailed on page 178, demonstrate substantially lower levels of impurities. While still not being spectroscopic grade ethanol, these samples could well represent ordinary pharmaceutical grade ethanol. It is these samples the authors claim are “different”. However the evidence presented for this is weak to nonexistent.

Figure 1 presents one trace each for Nat mur and Nux vomica, each at 6C, 12C and 30C potencies. The traces are said to be “representative”, however with no information on repeatability or how the “representative” traces were selected, it is impossible to say whether there is in fact any real difference between any of the six spectra.

Figure 2 purports to address this point, but then fails to present the necessary data. The legend declares that 10 samples of each of the six remedy preparations were analysed. The normal way to present such data would be as mean absorbance standard deviation for each wavelength point, or at least for a representative selection of wavelength points. Statistical analysis could then be used to demonstrate whether or not there was a real difference between any of the remedies or potencies. However, the authors have chosen instead to present something they term “envelope of differences”. This is not a recognised method of handling such data, and it is not explained. We surmise that “extreme” high and low traces for each preparation were chosen to provide an impression of the range of results obtained. However, the fact that on two of the graphs the traces appear to cross may argue against this interpretation.

A further difficulty with figure 2 is that the upper (open circles) trace in the top graph of fig 2a (30C Nat mur) appears to be a duplicate of the upper (closed circles) trace in the top graph of fig 2b (30C Nux vom). Comparison with other traces of the two remedies indicates that this trace is really one of Nux vom, which has been duplicated into the Nat mur graph in error.

Paucity of data, ambiguity of presentation and lack of statistical analysis prevent any conclusions being drawn from the information in figure 2.

Comparison of figure 2 with figure 1 reveals that all six traces presented in figure 1 are taken from figure 2, in each case the closed-circles traces. If indeed the traces in figure 2 represent the extreme range of results obtained, this is startling, as the traces in figure 1 are stated to be “representative”. In addition, while it does appear that the Nux vom samples tended to demonstrate higher absorbances than the Nat mur samples (excluding the obvious mistake noted above), in two out of the three potencies the higher Nux vom trace from fig 2 has been chosen for inclusion in fig 1, thus exaggerating the apparent difference.

Figure 3 (b and c) again repeats the same six traces as figure 1, this time grouped by remedy. Presented in this way, it is clear that there is no difference between the three potencies of Nat mur, and that while variation between the Nux vom potencies is a little more pronounced, again all three traces appear to come from the same population. The same is true of the three potencies of “succussed ethanol” presented in fig 3a.

On simple visual inspection it does appear that there may be genuine differences between the three remedies (although no statistics are presented to allow this to be tested), with the Nat mur showing the lowest absorbtion and the Nux vom the highest, with the succussed ethanol lying somewhere between. Nevertheless, these differences are entirely consistent with small differences in purity of the ethanol stock used for preparation of the three remedies – small, that is, relative to the very high level of impurity evident in the “plain ethanol” sample presented alongside. This degree of variation in UV absorbance is entirely to be expected between different batches of pharmaceutical grade ethanol, which is not prepared with spectroscopic analysis in mind. The authors make no mention of having stipulated to Hahnemann Laboratories that all material sent to them should be prepared from the same stock bottle, and the data presented indicate that the different remedies, possibly prepared at different times, simply came from different bottles of ethanol.

We hope you agree that these are very serious points, and it is regrettable they were not identified by your own scrutineering process. It is clear that the data presented are wholly inadequate to support the authors’ assertion that UV spectroscopy can differentiate between the two remedies, and between different potencies of the remedies. If the authors wish to test their assertion so that it can be substantiated it will be necessary to repeat the work from the beginning, ensuring that all samples used in the study are sourced from the same bottle of stock solvent, that all duplicate preparations for precision assessment are separately prepared de novo from the mother tinctures, and that sufficient data are generated to allow robust and valid statistical analysis of the results.

Yours faithfully,


  1. Rao, M. L., Roy, R., Bell, I. R & Hoover, R. (2007) The defining role of structure (including epitaxy) in the plausibility of homeopathy. Homeopathy 96, 175-182.
  2. Sigma Aldrich catalogue, ACS spectrophotometric grade ethanol 95.0%, at
  3. Sigma Aldrich catalogue, USP/NF grade ethanol 190 proof, at

"The way we vote will depend, ultimately, on whether we are persuaded to hope or to fear." - Aonghas MacNeacail, June 2012.

Last edited by Rolfe; 23rd August 2007 at 06:07 AM. Reason: Formatting
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