Talk:Henry Cavendish

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Most Wikipedia articles about scientists have the biographical material very early, so that's where I've put it in this case. I don't know if it's official policy to structure the articles that way, but plenty do so, and now this article does too. -- Astrochemist 02:43, 7 May 2007 (UTC)

Content issues[edit]

Is the "Other work" section correct? Did Cavendish really get six-significant figure data? I don't know. -- Astrochemist 02:43, 7 May 2007 (UTC)

Since the opening sentences highlight Cavendish's work on H2, it would be good to have a section on hydrogen's discovery. -- Astrochemist 02:43, 7 May 2007 (UTC)

Article status[edit]

Er, is this still a stub? I'm not quite clear when stubs graduate, but this seems pretty complete. Thoughts? Mashford 21:43, 10 Mar 2005 (UTC)

Cavendish is also credited with one of the earliest accurate calculations of the density of the earth. It would be good to give the density of the earth then! How can we call this fairly complete if one of the guy's main achievements in life was to calculate something which we don't specify. I came here to know the earth's average density (not including the atmosphere), and the one web page most likely to contain the info seems to be missing it. 19:36, 28 December 2006 (UTC)

Endowment of Cavendish Laboratory[edit]

"He left a large estate on his death which was used to endow the Cavendish Laboratory at Cambridge University in 1871."--This appears to be in conflict with text at Cavendish Laboratory and at William Cavendish, 7th Duke of Devonshire. Jim 21:30, 4 November 2005 (UTC)

G determination[edit]

I have changed the section "Earth's mass" because there were some mistakes

His measurement of the earth's mass was accepted until the 17th century? Really? Isn't that, what, 40 odd years before he was born?

You are correct; that is an error. It should read 20th century. I'm correcting it.

The wrong century appears in, which likely took the text from Wikipedia. The correct century appears in other works. Snezzy 12:33, 28 November 2006 (UTC)

Minor error in gravitation experiment[edit]

Great article! It's very well written and researched. I did notice a minor technical error in the section on The density of the earth. The Cavendish experiment didn't '...measure the gravitational attraction between two 350 lb lead spheres' , but between those spheres and smaller 2 inch 1.61 lb lead spheres attached to his torsion balance beam. See the 2nd para of Cavendish's paper, online in A.S. McKenzie, ed., Scientific Memoirs, Vol.9: The Laws of Gravitation, 1900, p.59 or your ref 1,R. McCormmach & C. Jungnickel, Cavendish, 1996, p.337. --Chetvorno 18:21, 17 August 2007 (UTC)

Corrected error --Chetvorno 00:56, 28 August 2007 (UTC)

Should 'his Clapham Commons estate' be '... Common ...'? If noone objects, I'll change it. Sam Dutton (talk) —Preceding comment was added at 07:56, 19 March 2008 (UTC)

Is there any way more biographical information can be included?[edit]

I found this interesting quotation about Cavendish:

"He did not love; he did not hate; he did not hope; he did not fear; he did not worship as others do. He separated himself from his fellow men, and apparently from God. There was nothing earnest, enthusiastic, heroic, or chivalrous in his nature, and as little was there anything mean, groveling, or ignoble. He was almost passionless. All that needed for its apprehension more than the pure intellect, or required the exercise of fancy, imagination, affection, or faith, was distasteful to Cavendish. An intellectual head thinking, a pair of wonderfully acute eyes observing, and a pair of very skillful hands experimenting or recording, are all that I realize in reading his memorials. His brain seems to have been but a calculating engine; his eyes inlets of vision, not fountains of tears; his hands instruments of manipulation which never trembled with emotion, or were clasped together in adoration, thanksgiving, or despair; his heart only an anatomical organ, necessary for the circulation of the blood. . .

Cavendish did not stand aloof from other men in a proud or supercilious spirit, refusing to count them his fellows. He felt himself separated from them by a great gulf, which neither they nor he could bridge over, and across which it was vain to stretch hands or exchange greetings. A sense of isolation from his brethren, made him shrink from their society and avoid their presence, but he did so as one conscious of an infirmity, not boasting of an excellence. He was like a deaf mute sitting apart from a circle, whose looks and gestures show that they are uttering and listening to music and eloquence, in producing or welcoming which he can be no sharer. Wisely, therefore, he dwelt apart, and bidding the world farewell, took the self-imposed vows of a Scientific Anchorite, and, like the Monks of old, shut himself up within his cell. It was a kingdom sufficient for him, and from its narrow window he saw as much of the Universe as he cared to see. It had a throne also, and from it he dispensed royal gifts to his brethren. He was one of the unthanked benefactors of his race, who was patiently teaching and serving mankind, whilst they were shrinking from his coldness, or mocking his peculiarities. . .He was not a Poet, a Priest, or a Prophet, but only a cold, clear Intelligence, raying down pure white light, which brightened everything on which it felt, but warmed nothing—a Star of at least the second, if not of the first magnitude, in the Intellectual Firmament."

From. Wilson, G. The life of the honorable Henry Cavendish. London: The Cavendish Society, 1851.

JocelynSequoia 06:40, 28 August 2007 (UTC)

Great quotes! Why don't you add some excerpts from them to the article? --Chetvorno 15:24, 28 August 2007 (UTC)

Recent changes[edit]

I tried to clean up some of the writing, but there's still a lot more to do. Also, I removed a comment about the Earth's mass in one place because the numerical value was given in units of weight, and there was no indication of who did either the calculation or the measurement. Can these be located and put back in? -- Astrochemist 02:23, 1 September 2007 (UTC)

Need citation[edit]

I added an interesting quote from Bryant (see sources) but i have no idea how to cite it. Please help! —Preceding unsigned comment added by (talk) 21:30, 28 November 2007 (UTC)

Either Green or Maxwell is lying or ...[edit]

.... or the author of this passage has it completely worng:

  • Cavendish's electrical experiments did not become known until they were collected and published by James Clerk Maxwell a century later, in 1879,

But George Green knew about (one of) them in 1828:

  • noticing an excellent paper, presented to the Royal Society by one of the most illustrious members of that learned body, which appears to have attracted little attention, but which, on examination, will be found not unworthy the man who was able to lay the foundations of pneumatic chymistry, and to discover that water, far from being according to the opinions then received, an elementary substance, was a compound of two of the most important gasses in nature.
  • It is almost needless to say the author just alluded to is the celebrated CAVENDISH, who, having confined himself to such simple methods, as may readily be understood by any one possessed of an elementary knowledge of geometry and fluxions, has rendered his paper accessible to a great number of readers; and although, from subsequent remarks, he appears dissatisfied with an hypothesis which enabled him to draw some important conclusions, it will readily be perceived, on an attentive perusal of his paper, that a trifling alteration will suffice to render the whole perfectly legitimate.
  • Footnote: In order to make this quite clear, let us select one of CAVENDISH's propositions, the twentieth for instance, and examine with some attention the method there employed. The object of this proposition is to show, that when two similar conducting bodies communicate by means of a long slender canal, and are charged with electricity, the respective quantities of redundant fluid contained in them, will be proportional to the $n-1$ power of their corresponding diameters:

(Cited from Green's well known Essay on the Application of mathematical Analysis to the theories of Electricity and Magnetism.) --Rwst (talk) 15:20, 9 June 2008 (UTC)

OK, I've completed the section, and added a reference to the mentioned paper. --Rwst (talk) 15:41, 9 June 2008 (UTC)

As communication wasn't as easy then as it is today (no search engines either), it's entirely possible Maxwell simply didn't know about Green's writing on this. Some more recent secondary sources on this issue would not hurt. Have mörser, will travel (talk) 20:03, 25 September 2011 (UTC)

Date of death[edit]

The Peerage, and some other sources seem to think he died on 10 March 1810. (There’s even one site [1] that gives both dates, so that speaks volumes for their credibility.) Any ideas about this discrepancy? "The Peerage" is not known for getting such details wrong (not that it's impossible). -- JackofOz (talk) 06:20, 9 July 2008 (UTC)

I wouldn't take The Peerage as being a solid source. It is a one man show "This website is the result of around fourteen years of work by one (somewhat eccentric) person collecting information" and "NOTE: this site is very much still a work in progress, and is bound to have a more than a few errors - please pay attention to the citations given when evaluating the quality and accuracy of this data." The source given for dob is Burke's Peerage. This is behind a paywall, but someone should be able to check for us if necessary. The Peerage also cites the Oxford Dictionary of National Biography, also behind a paywall, but I do have access and it gives 24 February 1810 as his death and 12 March as the date of his burial. The 10 March date looks like an error to me at the moment. Possibly a Julian/Gregorian calendar issue, but the dates don't quite tie up with that idea. SpinningSpark 00:33, 25 January 2014 (UTC)

Too precise?[edit]

Cavendish also accurately determined the composition of Earth's atmosphere. He found that 79.167% is "phlogisticated air", now known to be nitrogen and argon, and 20.8333% is "dephlogisticated air"

Now that is accurate indeed; percentages specified up to 3 or 4 decimal places. However, these percentages are conspicuously close to simple fractions 19/24 and 5/24. Anybody know if that was what Cavendish really reported? --Jmk (talk) 12:38, 12 May 2009 (UTC)

I have not found Cavendish's original numbers, but the book "Cavendish: the experimental life" by Jungnickel and McCormmach gives, on page 358 [2], only two decimal places and says even that is too precise:
... the concentration of oxygen in the atmosphere is, according to Cavendish, 20.83 percent, which is remarkably near the currently accepted value of 20.95 percent. In making this comparison, it should be noted, Cavendish is credited with a somewhat greater precision than he would likely have claimed.
If this is true, then Wikipedia is surely mistaken in reporting 3—4 decimal places. Does anybody have any other information on this issue? --Jmk (talk) 13:34, 23 July 2009 (UTC)
20.8333%? Six significant figures is a bit hard to swallow. The Alembic Club reprinted some of Cavendish's papers. His original work may be there. - Astrochemist (talk) 21:52, 23 July 2009 (UTC)
In this version of the same book the author explains that remark in more detail in footnote 12 at the bottom of page 261 going over to page 262: this subsequent paper, in 1784, Cavendish noted that his dephlogisticated air contained impurities amounting to one thirtieth of its volume, which led him to suspect that common air contains one fifth part dephlogisticated air (that is, closer to 20 percent than to 20.83 percent).
SpinningSpark 18:27, 24 July 2009 (UTC)

It took me a long time, but I finally tracked down Cavendish's words. I rewrote the relevant section of the article. As always, assistance is welcome. Astrochemist (talk) 21:28, 25 July 2009 (UTC)

Great work. Thanks Astrochemist! --Jmk (talk) 10:03, 27 July 2009 (UTC)

Pronunciation of "Cavendish"?[edit]

Can anyone supply the correct pronnunciation of "Cavendish"? I recall hearing a lecture years ago where the speaker said the the second syllable of the name is accented.

Tashiro (talk) 22:03, 5 September 2011 (UTC)

G, mass of earth, density of earth[edit]

The article says: "It is not unusual to find books that erroneously describe Cavendish's work as a measurement either of the gravitational constant (G) or the Earth's mass,[15][16] and this mistake has been pointed out by several authors.[17][18] In reality, Cavendish's stated goal was to measure the Earth's density, and his result was later used to calculate G. The first time that this constant was used was in 1873, almost 100 years after the Cavendish experiment.[19] Cavendish's results also can be used to calculate the Earth’s mass." This doesn't really make much sense. The radius of the earth has been known, at least approximately, since ancient times. By Cavendish's time it was known pretty accurately. If its radius is known, then knowledge of its density is equivalent to knowledge of its mass. Similar considerations apply to G. The question of how Cavendish *conceptualized* or *described* his measurement is a separate one from the question of how it can actually be interpreted.-- (talk) 06:40, 14 September 2011 (UTC)

The Cavendish experiment directly yields density without any knowledge of Earth's radius. So yes, G and M can be calculated from the result with a knowledge of R, but that is not what is being measured. The claim is referenced; do you have any references to present in contradiction? SpinningSpark 16:30, 14 September 2011 (UTC)

Was he born in France?[edit]

In 1731 Nice belonged to the Duchy of Savoy. -- (talk) 21:06, 25 September 2013 (UTC)

How much argon in air?[edit]

"a volume of gas amounting to 1/120 of the original volume of common air.[6] By careful measurements he was led to conclude that, "common air consists of one part of dephlogisticated air [oxygen], mixed with four of phlogisticated [nitrogen]"." By my reading of his paper, he first concluded "one part...four" and then determined the 1/120th was not of common air but rather of the phlogisticated air, so that his estimate was that what we now know as argon was 1/150th of air. Please read p. 50 of the Alembic Club reprint and change the article if you agree.HowardJWilk (talk) 20:31, 21 February 2014 (UTC)

Very true that Cavendish gives the residue as 1/120 of the phlogisticated air, but extending that to a 1/150 proportion of common air is an unwarranted synthesis. That requires the unlikely assumption that the dephlogisticated portion of common air will have zero residue. Cavendish has nothing to say (at least in that passage) about how much residue is to be got from the dephlogisticated component of common air. This could be the same, less, or more than the phlogisticated component. I don't know the answer to that, but saying anything at all in the article will certainly require a source in any case. SpinningSpark 14:00, 22 February 2014 (UTC)
Your point is well taken. So instead of my 1/150 of (all) air, why don't we change "1/120 of the original volume of common air" to "1/120 of the volume of the phlogisticated air (nitrogen)"?HowardJWilk (talk) 17:02, 22 February 2014 (UTC)
That sounds good to me. However, it would be preferable if a secondary source could be found saying that. Cavendish's own paper is a primary source and that still means we are trying to interpret it ourselves. A quick gbooks search picks up numerous books [3][4][5][6][7][8][9] reporting this result, but this one is the first one I found that picks up on the difference between whole air and nitrogen in Cavendish, and I have to admit, Cavendish is not very clear himself. He says "of the whole" but does not explicitly state the whole what. SpinningSpark 19:08, 22 February 2014 (UTC)

Bottom line is I'm not going to change it; this sort of thing is above my pay grade. But I searched for the word "whole" in the book, and this is what I found (some count might be off by 1, maybe, but that won't change my conclusion): The word is used 22 times. 1 is the one in question; 5 are N/A to gases (e.g., "during the whole experiment"); 1 refers to all air; and 15 refer to a single gas or a specific composition of gas not equivalent to all air. So I'm convinced the "whole" in question refers to phlogisticated air and not all air.

As far as references go, I think what's happened is that one or a few people wrote that Cavendish found that [argon] was or was about 1/120th of air, and then that got quoted and the quotes got quoted, etc. I think another factor leading to the more common interpretation is that it makes Cavendish look much better in that the 1/120 is closer, impressively close to the modern value of about 1/108.

So I'm not going to change it, but it sure would be swell if some noted historian of chemistry assumed the responsibility of changing 229 years of received wisdom.HowardJWilk (talk) 02:37, 24 February 2014 (UTC)

I've made the edit. SpinningSpark 08:13, 24 February 2014 (UTC)
-) (The first time in my life I've used one of those things, and perhaps the last.) (talk) 14:52, 24 February 2014 (UTC)

OK, :-) (The second time in my life I've used one of those things, and perhaps the last.) (Wasn't signed in the first time.) (And the : at the beginning threw off the intended formatting instead of being part of the intended emoticon.)HowardJWilk (talk) 01:59, 25 February 2014 (UTC)