Atomic weight of Be ?

[ERIC SCERRI]

I have been looking into the early use of atomic weights by the discoverers of the periodic table.

Van Spronsen’s 1969 classic book has a rather good table that displays the atomic weights of many chemists of the day. (pp. 46-49)

I am intrigued by a single entry, that of a value of 9 for beryllium under the column headed De Chancourtois, while Cannizzaro, who is widely credited with having established a set of definitive atomic weights, omits any value whatsoever for Be.  Berzelius thinks it is 53!

The question of the atomic weight of beryllium presented a genuine problem since it was not clear whether it was di- or tri-valent.  

I have a section on this in my 2007 book on the periodic table (pp. 127-8) and again on pp. 141-2 in the second edition of 2020.  

The issue was finally sorted out by Mendeleev, who opted for di-valency, which meant that beryllium was assigned an atomic weight of 9.4.

But De Chancourois’ spiral periodic system appeared a full 7 years before Mendeleev’s first published table of 1869.

Where could De Chancourtois have obtained more or less the same value so early?

Regards

Eric

[johnmarks9]

Alexandre Émil Béguyer de Chancourtois (what a name!) was, of course, a geologist and probably familiar with beryl (Be valency +2) and maybe other beryllium compounds. 

A search of Comptes Rendus and other early 19th century geological, crystallographic or mineralogy journals may be a source worth examining to answer your question.

Regards,

John Marks

[ERIC SCERRI]

Thank you John,

As I tried to explain, the valency of Be was generally taken to be 3, not 2, before Mendeleev’s intervention.

This led to an incorrect atomic weight.

Eric Scerri

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ERIC SCERRI PhD

UCLA

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[Mark Leach]

Hi Eric & All,

Interesting. I had not clocked that Cannizzaro had omitted Be:

https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=1047

Or lithium (or helium… which, to be fair, had not been discovered…)

I see from the attached table, that Berzelius had originally said 10.9 which he then modified to 53 (a big jump!).

Perhaps De Chancourtois used the original 1815 Berzelius logic?

Beryl has a complex stoichiometry: Be3Al2(SiO3)6 so it would not be surprising if this gave an erroneous weight for Be. After all, Daubeny thought Al had a weight of 10:

https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=337

Mark

Mark Leach

meta-synthesis

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[René]

Hi Eric

This is an interesting topic of which I knew little.

On Berzelius’ value of 53, Parsons (1904, p. 721) wrote that:

"The first determinations of the equivalent of beryllium were made by Berzelius in 1815, and consisted of a single analysis each of an undoubtedly impure hydrous sulphate and chloride, both of which were probably also basic in character. The results are, therefore, of no interest in a discussion of the atomic weight of this element."

Berzelius also favoured Be2O3 as the formula of the oxide which couldn’t have helped.

Parsons (1904, p. 723) went on to list the following determinations of the atomic weight of beryllium:

                              Ratio determined   Mean O = 16

============================================================

1842 Awdejew               BeO : BaS04        9.34

1854 Weeren               BeO : BaS04        9.27

1855 Debray               BeO : 4C02         9.34

------------------------------------------------------------

1869 Klatzo               BeO : BaSO         9.28

1880 Nilson and Petterson  BeS04.4H20 : BeO   9.104

1891 Krüss and Moraht      BeS04.4H20 : BeO   9.05

Evidently De Chancourtois relied on one or more of the first three, all of which predate his 1862 Telluric Screw.

He was in good company since Newlands (1864) and Odling (1864) also showed Be as 9, again predating Mendeleev’s first periodic system of 1869.

Looking closer at De Chancourtois’ Teulluric Screw it shows GlO (i.e. BeO)—in the column to the left—

as the basis for the atomic weight of 9 (rounded down): https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=7

That said, as you know, since Be appeared to behave like Al there was an expectation by others that beryllium oxide ought to be Be2O3 rather than BeO, and that its atomic weight would therefore be ~13.5.

There is some discussion on the supposed experimental basis for this higher atomic weight in Nature (1880, pp. 57–58).

As you noted, you also discuss this at pp. 141–142 of the 2nd ed of your Red Book.

De Chancourtois and aluminium

All that said, I don’t understand what you wrote about De Chancourtois grouping Al with the alkali metals (p. 81):

One final comment should perhaps be made about De Chancourtois. His lack of

chemical knowledge may have been a hindrance in some cases, and conversely, his

emphasis on geological factors may have misled him in the development of the periodic

system. For example, he stated that the isomorphism between feldspars and pyroxenes

had been the starting point of his system. The element aluminum appears to function

analogously to the alkali metals, a fact that does not necessarily indicate that aluminum

should be grouped together with alkali metals such as sodium and potassium. But this is

precisely what De Chancourtois did in his system. In fact, he even changed the atomic

weight, or characteristic weight, as he termed it, in the case of aluminum to make it fall

neatly into line with the alkali metals. Had he known more chemistry, he might not have

taken this unjustified step.

On what basis did you conclude that De Chancourtois aligned Al with the alkali metals, and that he changed the atomic weight of Al, to achieve this?

In his Telluric Screw, Al was aligned under B and over Si-Ni-As-La-Pd. Immediately to the left are Li-Na-K-Mn-Rb-Ru-Th. Al thus does not fall into line with the alkali metals.

De Chancourtois also showed Al with an atomic weight of 27, which is close to the accepted value (26.98).

René

• Nature 1880, The atomic weight of beryllium, 23, https://doi.org/10.1038/023057b0
• Newlands JAR 1864, Chemical News, 10, 59-60
• Parsons CL 1904, A revision of the atomic weight of beryllium, J. Am. Chem. Soc., 26, 7, 721–740
• Odling W 1864, On the proportional numbers of the elements," Quarterly Journal of Science, 1, 642-648

[ERIC SCERRI]

Thanks for all this information, René.

On Jan 22, 2026, at 8:40 PM, René <re...@iinet.net.au> wrote:

Hi Eric

This is an interesting topic of which I knew little.

On Berzelius’ value of 53, Parsons (1904, p. 721) wrote that:

"The first determinations of the equivalent of beryllium were made by Berzelius in 1815, and consisted of a single analysis each of an undoubtedly impure hydrous sulphate and chloride, both of which were probably also basic in character. The results are, therefore, of no interest in a discussion of the atomic weight of this element."

Berzelius also favoured Be2O3 as the formula of the oxide which couldn’t have helped.

Parsons (1904, p. 723) went on to list the following determinations of the atomic weight of beryllium:

                              Ratio determined   Mean O = 16

============================================================

1842 Awdejew               BeO : BaS04        9.34

1854 Weeren               BeO : BaS04        9.27

1855 Debray               BeO : 4C02         9.34

------------------------------------------------------------

1869 Klatzo               BeO : BaSO         9.28

1880 Nilson and Petterson  BeS04.4H20 : BeO   9.104

1891 Krüss and Moraht      BeS04.4H20 : BeO   9.05

This is especially useful.  

I would need to look at De C’s original articles to see where he obtained his atomic weights.  I don’t recall whether I looked at them when I put together the book more than 20 years ago now!

Evidently De Chancourtois relied on one or more of the first three, all of which predate his 1862 Telluric Screw.

He was in good company since Newlands (1864) and Odling (1864) also showed Be as 9, again predating Mendeleev’s first periodic system of 1869.

A good point. 

Looking closer at De Chancourtois’ Teulluric Screw it shows GlO (i.e. BeO)—in the column to the left—

as the basis for the atomic weight of 9 (rounded down): https://www.meta-synthesis.com/webbook/35_pt/pt_database.php?PT_id=7

That said, as you know, since Be appeared to behave like Al there was an expectation by others that beryllium oxide ought to be Be2O3 rather than BeO, and that its atomic weight would therefore be ~13.5.

There is some discussion on the supposed experimental basis for this higher atomic weight in Nature (1880, pp. 57–58).

As you noted, you also discuss this at pp. 141–142 of the 2nd ed of your Red Book.

De Chancourtois and aluminium

All that said, I don’t understand what you wrote about De Chancourtois grouping Al with the alkali metals (p. 81):

One final comment should perhaps be made about De Chancourtois. His lack of

chemical knowledge may have been a hindrance in some cases, and conversely, his

emphasis on geological factors may have misled him in the development of the periodic

system. For example, he stated that the isomorphism between feldspars and pyroxenes

had been the starting point of his system. The element aluminum appears to function

analogously to the alkali metals, a fact that does not necessarily indicate that aluminum

should be grouped together with alkali metals such as sodium and potassium. But this is

precisely what De Chancourtois did in his system. In fact, he even changed the atomic

weight, or characteristic weight, as he termed it, in the case of aluminum to make it fall

neatly into line with the alkali metals. Had he known more chemistry, he might not have

taken this unjustified step.

On what basis did you conclude that De Chancourtois aligned Al with the alkali metals, and that he changed the atomic weight of Al, to achieve this?

Sorry I don’t remember why I wrote that.  It would take me too far away from my primary concern to have to dig into this.  As I explained to Mark, I am trying to put together a lecture for the 100th anniversary of Cannizaro’s death in 1826.

Here’s something that may be of interest to you and others here.

Imagine trying to form the beginnings of a periodic table based on Berzelius’ list of atomic weights of 1845.

You arrange the elements in order of increasing atomic weights and cut the sequence in order to reflect chemical similarities.  Here’s how it would look.

It works for groups 15, 16 and 17 (in modern group numbering)

but it fails for the other trhee potential groups as shown below (shown by asteriskes).

---------------------------------------------------------------------------------------------------------------

Now do it using Cannizaro’s atomic weights of 1860.

Of the 7 groups that are formed below, only one of them (Li and Mg) is incorrect as shown by the asterix.  

To me this shows why putting a resonable periodic table together was not possible before Cannizaro published his 1860 values.

Of course there may have been a set of atomic weights after Berzelius 1845 and before Cannizaro that could have done a good job but I would need to look into it further.  Maybe Debray?  Do you know if he published an extensive list like Berzelius and Cannizaro did?  

The question of the atomic weight of beryllium presented a genuine problem since it was not clear whether it was di- or tri-valent.  

I have a section on this in my 2007 book on the periodic table (pp. 127-8) and again on pp. 141-2 in the second edition of 2020.  

The issue was finally sorted out by Mendeleev, who opted for di-valency, which meant that beryllium was assigned an atomic weight of 9.4.

Your data from Awdejew, Weeren etc. suggests that I gave Mendeleev too much credit for arriving at a value of about 9.  

But De Chancourois’ spiral periodic system appeared a full 7 years before Mendeleev’s first published table of 1869.

Where could De Chancourtois have obtained more or less the same value so early?

Regards

Eric

[René]

Thanks Eric for sharing your thoughts on what seems to be an under-lit corner of periodic table history.

Here’s something that may be of interest to you and others here.

[trim]

Now do it using Cannizaro’s atomic weights of 1860.

Of the 7 groups that are formed below, only one of them (Li and Mg) is incorrect as shown by the asterix.

To me this shows why putting a resonable periodic table together was not possible before Cannizaro published his 1860 values.

It seems to me that you’re giving too much credit to Cannizzaro?

In his letter of 1858 he included atomic weight values for H-B-C-N-O and Na-Mg-Al-Si-P-S-Cl but not, as far as I can see, for Li-Be-F, resulting in:

H  B  C  N  O

Na Mg Al Si P S Cl

Of the five groups, 4 are incorrect and there are 2 orphans. His values for P and S are the same (32). 

The sequence of a pentad followed by a heptad lacks the regular segmentation needed for periodicity to become visually apparent. Then again, Cannizzaro wasn't looking for periodicity; he was concerned with getting atomic weights right.

Van Spronsen does however list Cannizzaro values for Li-Be-Fi which were presumably inferred by him (van Spronsen).

Notably, van Spronsen does not give a source aside from Cannizzaro (1860) which is the 1858 letter reproduced as a pamphlet and circulated at the Karlsruhe congress in 1860. I see van Spronsen also listed a value of 31 for P, which is not consistent with Cannizzaro’s value of 32. For that matter, van Spronsen listed 51 values whereas Cannizzaro gave values for only 30 elements.

In contrast, De Chancourtois (1862) included values for H-Li-Be-B-C-N-O-F and Na-Mg-Al-Si-P-S-Cl, ostensibly resulting in:

H

Li Be B  C  N O F

Na Mg Al Si P S Cl

This is indeed the start of a reasonable periodic table.

In this light it may be more reasonable to say that:

• Cannizzaro laid the foundation for putting a reasonable periodic table together;
• De Chancourtois paved the way; and
• Mendeleev seized the day.

regards, René

[ERIC SCERRI]

On Jan 24, 2026, at 9:29 PM, René <re...@iinet.net.au> wrote:

Thanks Eric for sharing your thoughts on what seems to be an under-lit corner of periodic table history.

Here’s something that may be of interest to you and others here.

[trim]

Now do it using Cannizaro’s atomic weights of 1860.

<Screenshot 2026-01-22 at 9.23.00 PM.png>

Of the 7 groups that are formed below, only one of them (Li and Mg) is incorrect as shown by the asterix.

To me this shows why putting a resonable periodic table together was not possible before Cannizaro published his 1860 values.

It seems to me that you’re giving too much credit to Cannizzaro?

In his letter of 1858 he included atomic weight values for H-B-C-N-O and Na-Mg-Al-Si-P-S-Cl but not, as far as I can see, for Li-Be-F, resulting in:

H  B  C  N  O

Na Mg Al Si P S Cl

Of the five groups, 4 are incorrect and there are 2 orphans. His values for P and S are the same (32). 

The sequence of a pentad followed by a heptad lacks the regular segmentation needed for periodicity to become visually apparent. Then again, Cannizzaro wasn't looking for periodicity; he was concerned with getting atomic weights right.

Van Spronsen does however list Cannizzaro values for Li-Be-Fi which were presumably inferred by him (van Spronsen).

Notably, van Spronsen does not give a source aside from Cannizzaro (1860) which is the 1858 letter reproduced as a pamphlet and circulated at the Karlsruhe congress in 1860. I see van Spronsen also listed a value of 31 for P, which is not consistent with Cannizzaro’s value of 32. For that matter, van Spronsen listed 51 values whereas Cannizzaro gave values for only 30 elements.

Yes, I’ve also been looking at Van Spronsen again.  I agree that he does not give any citations for Cannizzaro’s atomic weights.

As Mark Leach pointed out he list Ti as 56 in his Sunto, whereas Van Spronsen reports 50, rather mysteriously.  

Even more puzzling, Van Spronsen gives 60 references in his chapter 3 that contains the table that I shared with atomic weights from vaerious authors, but not one single citation to Cannizzaro !

This is rather disappointing.  

Does anybody know the source of the column headed Cannizzaro 1860 on p. 47 of Van Spronsen?

I am in the process of also asking several Italian colleagues.

Best

Eric

In contrast, De Chancourtois (1862) included values for H-Li-Be-B-C-N-O-F and Na-Mg-Al-Si-P-S-Cl, ostensibly resulting in:

H

Li Be B  C  N O F

Na Mg Al Si P S Cl

This is indeed the start of a reasonable periodic table.

In this light it may be more reasonable to say that:

• Cannizzaro laid the foundation for putting a reasonable periodic table together;
• De Chancourtois paved the way; and
• Mendeleev seized the day.

regards, René

[René]

G'day Eric

Even more puzzling, Van Spronsen gives 60 references in his chapter 3 that contains the table that I shared with atomic weights from vaerious authors, but not one single citation to Cannizzaro !

This is rather disappointing.  

Does anybody know the source of the column headed Cannizzaro 1860 on p. 47 of Van Spronsen?

Ostensibly, yes, on p. 43 van Spronsen refers to the source of the column:

Cannizzaro's values for the atomic weights, based mainly on the views of Avogadro and Gerhardt, were not made public until two years after the Congress, in the Jahresbericht über die Fortschritte der Chemie [Annual report on the progress of chemistry]. It was thanks to this Congress that in the decade following 1860 several scientists were able to discover the periodic system of elements and that De Chancourtois was actually able to do so as early as 1862 by the use of atomic weights that were correct or almost correct in all but a few cases (see 3.5).

Jahresbericht über die Fortschritte der Chemie [JFC] is a little confusing in that each one is published in the year after the reporting year. So what happened in 1858 is published in 1859.

I looked up the JFC for each of the reporting years 1858 through 1864.

The only specific mention I could find of Cannizzaro’s atomic weights was in the 1858 volume, published in 1859, p. 11, which gave 19 of his 30:

JFC van Spronsen

====================================

Hydrogen 1 1

Lithium 7 7  *

Nitrogen 14 14

Sodium 23 23

Magnesium 24 24

Phosphorus 31 31  **(Cannizzaro = 32)

Chlorine 35.5 35.5

Potassium 39 39

Calcium 40 40

Manganese 55 55

Iron 56 56

Copper 63 63

Zinc 66 65  **(Cannizzaro = 66)

Silver 108 108

Tin 117.6 118 **(Cannizzaro = 117.6)

Barium 137 137

Platinum 197 197

Mercury 200 200

Lead 207 207

* no such weight was explicitly given by Cannizzaro in Sunto (see below)

** discrepancy in values attributed to Cannizzaro

The mention of Cannizzaro’s atomic weights in the JFC review of the year 1858 makes sense since Cannizzaro’s "Sunto" letter was published in 1858, in Il Nuovo cimento (in Italian) vol. 7, Società italiana di fisica, pp. 321–366.

While van Spronsen claimed that Cannizzaro's values for atomic weights were not made public until two years after the Congress, there’s no specific mention of these values in the JFC published in 1862, two years after the Congress. I suggest van Spronsen would’ve read better as:

"Cannizzaro's values for the atomic weights, based mainly on the views of Avogadro and Gerhardt, had been made public two years before the Congress, in Il Nuovo cimento, with little impact."

I have two further concerns.

Firstly, van Spronsen has another table of atomic weights, including some of those reportedly of Cannizzaro (1860), on p. 57. Comparing p. 47 with p. 57, there are three discrepancies: Ru 197 v 104; Pd 106 v 107; Pt 197 v 197.5

Secondly, on p. 80 van Spronsen wrote:

Cooke reported having used the atomic weights given in a list in the 1852 Jahresbericht [27] by Liebig and Kopp. The copy available to us contained no table of atomic weights, however.

The JFC published in 1852, containing a summary of progress in 1851, does however have a list of atomic weights on its last page. 

What to make of all this?

van Spronsen’s writings seemingly include some inexplicable discrepancies.

That said, I think the question of a source of values in the column headed Cannizzaro 1860 on p. 47 of van Spronsen is not so important, given there is the confirmed list of 30 reported by Cannizzaro in Sunto (1958), as extracted by Mark.

Now, in respect of the importance of Sunto, Hartley (1966) wrote:

The decisive moment had come after the close of the Conference when Pavesi distributed some reprints of Cannizzaro’s Sunto. Lothar Meyer was given a copy which he put in his pocket to read on his way home (2). ‘I read it again and again’, he wrote, ‘and I was amazed at the clear light which that little paper shed on the main subjects of our debates. The scales fell from my eyes, doubts disappeared and a feeling of certainty took their place. If I was able later to help in clearing up the points at issue and cooling the hot tempers, I owe much to Cannizzaro’s pamphlet.’ Many other members of the Conference felt the same. The tides of battle began to ebb; the old atomic weights of Berzelius once more came into their own. After the apparent discrepancies between the laws of Avogadro and Dulong and Petit had been explained by Cannizzaro, both could be used to the full and thereby the doctrine underlying the chemical values of the elements was put on a sound foundation without which the theory of atomic linkage could not have progressed.

It is thus certain that it was only after reading Cannizzaro’s Sunto that Lothar Meyer realized the logic and clarity of his exposition. Without the convincing tables of values in the paper it must have been difficult to do justice to it verbally. How different the result might have been if Cannizzaro had had lantern slides or a hand-out. Mendeleev’s enthusiastic praise of Cannizzaro in his letter of 7 September to his teacher Voskresensky must also have been written after he had read the paper as he quotes the tables in it (3).

Two years later Lothar Meyer wrote his Modernen Theorien der Chemie, published in 1864 which did much to clarify chemists’ thinking about atoms and molecules, so that by 1870 Cannizzaro’s views were generally accepted, except in France. Academician Figurowsky’s biography of Mendeleev contains the following statement about the genesis of the periodic table, taken from some unpublished reminiscences by his son, D. I. Mendeleev (8): ‘The decisive moment in the development of my theory of the periodic law was in 1860, at the conference of chemists in Karlsruhe, in which I took part, and at which I heard the ideas of the Italian chemist S. Cannizzaro. I regard him as my immediate predecessor, because it was the atomic weights which he found, which gave me the necessary reference material for my work. I noted immediately that the modifications he proposed to the atomic weights introduced a new pattern into Dumas’ groupings, and it was then that I was struck with the essential idea of a possible periodicity in the properties of the elements on increase in the atomic weight. I was still hindered by the incongruities in the atomic weights accepted at this time; but I was firmly convinced that this was the direction in which to pursue my work.’

So in spite of its inauspicious ending the Conference, thanks to Cannizzaro’s presence, was destined to have a decisive influence on the progress of chemical theory and to be a great landmark in its history.

(2) Ostwald’s Klassiker Nr. 90. Abriss eines Lehrganges der Theoretischen Chemie vorgetragen an der K. Universität Genf von Prof. S. Cannizzaro. Herausgegeben von Lothar Meyer. Leipzig, Verlag Engelmann, 1891.

(3) Mendeleev. Letter to Prof. Voskresensky.

Dmitrii Ivanovich Mendeleev, his Life and Works by M. I. Mladentsev and V. E. Tishchenko. U.S.S.R. Academy of Sciences, 1938. Vol. I, pp. 250–258.

(8) N. A. Figurowsky. Dmitrii Ivanovich Mendeleev. Izd. Akad. Nauk. SSSR, Moscow, 1961, pp. 44–51.

Hartley H 1966, Stanislao Cannizzaro, F.R.S. (1826-1910) and the first international chemical conference at Karlsruhe in 1860, Notes Rec. R. Soc. Lond., 21, 56–63, doi: 10.1098/rsnr.1966.0006

I have not seen a better attestation as to the eventual impact of Cannizzaro’s work, following the 1860 Congress, by no less than Lothar Meyer, and Mendeleev, and sixty years ago at that.

I hope these findings will be of some use to you.

René

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[Mario Rodriguez]

Hi all,

I would like to share a digital version of the work identified by René (https://books.google.es/books?id=W7NZAAAAcAAJ), along with a couple of comments.

- René marked discrepancies between the values reported in Sunto and those in JFC using * and **. However, these differences may simply reflect the fact that Cannizzaro himself updated some of his values in JFC after the publication of Sunto. In general, when an author publishes two different values, the later one should be considered the most reliable. Therefore, anyone aiming to compile Cannizzaro’s atomic weight values should take into account not only those in Sunto, but also the corrected values in JFC or any other later source if it exists. For reference, these values appear at the end of p. 12, even though Cannizzaro’s chapter begins at the end of p. 11.

- Interestingly, JFC also includes, at the beginning (p. XVIII), what appears to be a consensus atomic weight table from that year. I have found this table for other years in JFC as well.

I hope this is helpful,

Mario Rodríguez Peña

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[Mark Leach]

Hi Mario &v All,

VERY INTERESTING! Date: 1858

Oxygen, aluminium & sulfur are out by a factor of 2.

Very interesting to see fluorine (as Fl = 19.) The element was not discovered/isolated until 1886!

Just a few first observations!

Mark Leach

meta-synthesis

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[ERIC SCERRI]

Many thanks Rene,Mario and Mark for your detective work, references etc. 

The Hartley article. I reread this a few days ago. This seems to confirm Cannizzaro’s important role in revising atomic weights and his influence on M and LM. 

However it is curious that neither De Chancourtois nor Newlands attended Karlsruhe and yet discovered periodicity before M an LM. 

By far the best source for De C incidentally is the chapter by Carmen Giunta in the edited collection he edited in 2019 with Girolami and Mainz. 

Eric

On Jan 31, 2026, at 8:51 AM, Mark Leach <ma...@meta-synthesis.com> wrote:

Hi Mario &v All,

VERY INTERESTING! Date: 1858

To view this discussion visit https://groups.google.com/d/msgid/PT-L/004266BE-78EB-4FE8-AE69-6A5346AFAE1E%40meta-synthesis.com.

[René]

On 31 Jan 2026, at 16:03, 'Mario Rodriguez' via Periodic table mailing list <PT...@googlegroups.com> wrote:

Hi all,

I would like to share a digital version of the work identified by René (https://books.google.es/books?id=W7NZAAAAcAAJ), along with a couple of comments.

- René marked discrepancies between the values reported in Sunto and those in JFC using * and **. However, these differences may simply reflect the fact that Cannizzaro himself updated some of his values in JFC after the publication of Sunto. In general, when an author publishes two different values, the later one should be considered the most reliable. Therefore, anyone aiming to compile Cannizzaro’s atomic weight values should take into account not only those in Sunto, but also the corrected values in JFC or any other later source if it exists. For reference, these values appear at the end of p. 12, even though Cannizzaro’s chapter begins at the end of p. 11.

Thanks, Mario.

As far as I can see, the 19 atomic weight values listed in the Jahresbericht correspond to a subset of the 30 values given in Sunto, rather than to a revised or independently updated list. The two discrepancies in the Jahresbericht are that: Li is not mentioned in Sunto; and Sunto gave P as 32 rather than 31.

I haven't been able to find any evidence that Cannizzaro published an updated list of atomic weights after Sunto. I checked the Jahresbericht volumes through to those published in 1866 and didn't locate any such revision.

This leaves the provenance of the 51 values attributed to “Cannizzaro 1860” by van Spronsen unresolved. The presence of additional discrepancies elsewhere in van Spronsen’s tables (e.g. Ru, Pd, Pt) makes it difficult to treat van Spronsen’s Cannizzaro values as a secure reconstruction of Cannizzaro’s own values. As noted, I don’t think that matters much given the recognition that Cannizzaro’s work received post the Congress.

René

[René]

Hi Mark

On 1 Feb 2026, at 03:50, Mark Leach <ma...@meta-synthesis.com> wrote:

Hi Mario &v All,

VERY INTERESTING! Date: 1858

Agree.

Yes, as per Mario’s email, each year Jahresbericht über die Fortschritte der Chemie would include a list of (unsourced) Atomgewichte.

Oxygen, aluminium & sulfur are out by a factor of 2.

Yes, oxygen as 16, and sulfur as 32 don't show until the 1864 publication; aluminum as 27.4 not until 1865. I gather this occurred as a result of the progressive acceptance of Cannizzaro’s 1858 work.

Very interesting to see fluorine (as Fl = 19.) The element was not discovered/isolated until 1886!

Yes, in 1810, André-Marie Ampère suggested that hydrogen and an element analogous to chlorine constituted hydrofluoric acid. He also proposed in a letter to Sir Humphry Davy dated August 26, 1812 that this then-unknown substance may be named fluorine from fluoric compounds and the -ine suffix of other halogens.

[René]

On Sunday, February 1, 2026 at 5:22:19 AM UTC+11 scerri wrote:

Many thanks Rene,Mario and Mark for your detective work, references etc. 

The Hartley article. I reread this a few days ago. This seems to confirm Cannizzaro’s important role in revising atomic weights and his influence on M and LM. 

However it is curious that neither De Chancourtois nor Newlands attended Karlsruhe and yet discovered periodicity before M an LM.

De Chancourtois and Newlands based their work on Cannizzaro, so perhaps it is not so curious?

"Attempts were later made to show that the atomic weights of the elements could be expressed by an arithmetic function, and in 1862 A.-E.-B. de Chancourtois proposed a classification of the elements based on the new values of atomic weights given by Stanislao Cannizzaro's system of 1858."

https://web.archive.org/web/20020912030831/http://www.britannica.com/nobel/macro/5001_20_45.html

"Not until his next paper [Newlands 1864a] did Newlands use atomic weights based on the reforms Cannizzaro urged at the 1860 Karlsruhe Congress"

By far the best source for De C incidentally is the chapter by Carmen Giunta in the edited collection he edited in 2019 with Girolami and Mainz. 

Eric

René

[ERIC SCERRI]

Still curious that two attendees did not capitalize on Cannizzaro’s atomic weights before two who did not attend.

[René]

Chancourtois and Newlands were pattern seekers; Meyer and Mendeleev were philosophers?

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[ERIC SCERRI]

On Jan 31, 2026, at 10:23 PM, René <re...@iinet.net.au> wrote:

Chancourtois and Newlands were pattern seekers; Meyer and Mendeleev were philosophers?

Hi Rene,

This is a rather vague generalization.  A person can be both.

Incidentally, where are you reading that De C’ got his atomic weights from Cannizzaro?

I’m currently reading Giunta’s chapter, whch is the most in depth analysis of De C’ to date.  

He specifically says on p. 69 that De C. never mentioned Cannizzaro as his source of atomic weights.

I think Van Sp’ may have claimed this but we are starting to see that his scholarship was not all that reliable.

Eric

[René]

On 1 Feb 2026, at 18:14, ERIC SCERRI <sce...@g.ucla.edu> wrote:

On Jan 31, 2026, at 10:23 PM, René <re...@iinet.net.au> wrote:

Chancourtois and Newlands were pattern seekers; Meyer and Mendeleev were philosophers?

Hi Rene,

This is a rather vague generalization.  A person can be both.

Thanks Eric. I agree the distinction isn't absolute, and of course a person can be both. My comment was meant as a difference in emphasis, not a rigid taxonomy.

de C, as far as I know, essentially reported the Telluric Screw and let the pattern speak for itself. Newlands, as you noted, published some sixteen papers proposing alternative classifications (including the Law of Octaves), and later a retrospective book (1884) summarising those efforts. In both cases, the primary activity seems to have been the identification and testing of patterns.

In contrast, Meyer was so impressed by the Cannizzaro’s Sunto that he spent two to thee years on his book Die modernen Theorien der Chemie (1864) before publishing his tables. As you wrote (Red Book, p. 103), this work became one of the most authoritative treatments of the theoretical foundations of chemistry prior to the rise of physical chemistry. That strikes me as a very different kind of intellectual investment.

Similarly, my sense of DIM's work comes largely from Jensen’s Mendeleev on the Periodic Law (2002) and from your decision to devote a full chapter to him.

So my claim was that, relative to de C and N, Meyer and Mendeleev went well beyond pattern recognition and explicitly elaborated what the patterns meant or implied.

My impression is that this difference of emphasis is historically real, even if the boundary is necessarily porous.

Incidentally, where are you reading that De C’ got his atomic weights from Cannizzaro?

From Pauling:

"Attempts were later made to show that the atomic weights of the elements could be expressed by an arithmetic function, and in 1862 A.-E.-B. de Chancourtois proposed a classification of the elements based on the new values of atomic weights given by Stanislao Cannizzaro's system of 1858"

The expression "based on the new values of atomic weights given by Stanislao Cannizzaro's system" provides some wriggle room, as to what Pauling meant.

Hartog (1889, p. 188) too says that De C got his weights from Cannizzaro:

...the combining weights chosen as best suited to bring out clearly the numerical relations existing between them are those adopted by Cannizzaro in 1858, a striking fact when we recollect that de Chancourtois wrote oniy in 1862, at a date long before these numbers had gained anything like general acceptance.

However, earlier in the same paper Hartog (p. 186) also gave a translation of De C, as follows:

"My numbers, which are immediately deduced from the measure of the equivalents or other physical or chemical capacities of the different bodies, are, in the main, the proportional numbers given by the treatises on chemistry, these being reduced to half in the case of hydrogen, nitrogen, fluorine, chlorine, bromine, iodine, phosphorus, arsenic, lithium, potassium, sodium, and silver ; in other words, I either divide the equivalents of these bodies by two in the system in which oxygen is taken as 100, or multiply by two the equivalents of the other bodies in the system in which hydrogen is taken as unity."

Hartog PJ 1869, A first foreshadowing of the periodic law. Nature 41, 186–188, https://doi.org/10.1038/041186a0

It seems Hartog was interpreting De C’s talk of "the treatises on chemistry" as encompassing Cannizzaro’s work, given the similarties between the two sets of atomic weights. 

I’m currently reading Giunta’s chapter, whch is the most in depth analysis of De C’ to date.  

He specifically says on p. 69 that De C. never mentioned Cannizzaro as his source of atomic weights.

I think Van Sp’ may have claimed this but we are starting to see that his scholarship was not all that reliable.

Eric

René

[ERIC SCERRI]

Thanks Rene,

I appreciate having a range of quotations from authors who do think that De. C. obtained his weights from Cannizzaro, which I can cite.  I had not thought about looking in Hartog.  (It must be nice to have all the time in the world to devote to reading.  I’m still teaching full-time at UCLA).  

I have been reading Venable however.  What a wonderful account of early goings on.  

Another curious twist to this issue is that Cannizzaro possessed a copy of De Chancourtois's little book, but it had no annotations in it.

Too bad it was not the other way round, since it might clarify whether De C. did in fact obtain his weights from C.

Eric

-------------------------------------------------------------

[René]

Thanks Eric.

Cannizzaro’s thirty atomic-weight figures do appear in the Telluric Helix, except in seven cases where there was an overlap with other atomic weights. On paper, an overlap is tolerable; on a helix, it's impossible.

P and S both have weights of 32 according to Cannizzaro. De Chancourtois therefore had to adjust one of these values, since a helix requires a strict total ordering: every element must occupy a unique position along a continuous axis. No ties are allowed.

Thus he shows P as 31 and S as 32.*

[modern values: P 30.9; S 32.0]

The same applies to Fe and Ti at 56 apiece. Ti was downgraded to 48. **

[Ti 47.8; Fe 55.8]

Cannizzaro showed:

Br as 80. That wouldn't work since de Chancourtois shows Se as 80, so Br was downgraded to 79. ***

[Se 78.9; Br 79.9]

Sn as 117.6. That wouldn't work since de Chancourtois has Rh at 117, so Sn became 115. ***

[Rh 102.9; Sn 118.7]

Ba as 137. That wouldn't work since de Chancourtois has V at 137, so Ba becomes 136, aligning it under Sr. ***

[V 50.9; Ba 137.3]

Pt as 197. That wouldn't work since de Chancourtois has Ir at 197, so Pt becomes 199. ***

[Ir 192.2; Pt 195.0]

Hg as 200. That wouldn't work since de Chancourtois has Au at 200, so Hg becomes 204. ***

[Au 196.9; Hg 200.6]

* according to van Spronsen, P appears repeatedly in earlier tables as ~31.

** van Spronsen notes that Berzelius (1845) gave Ti as 48.

*** these adjusted values don't appear in earlier years, according to van Spronsen (pp. 46–47).

As you said in the Red Book, de Chancourtois’ limited chemical background evidently hindered him in some of these adjustments.

René

PS The Telluric Helix features 59 elements so at least some of the extra 29 were presumably sourced by de Chancourtois from the "chemical treatises" he referred to.

PPS I suggest you keep teaching at UCLA for as long as it lights your fire; we all find our own rhythm in these things.

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