Talk:Henry Cavendish

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Date of death[edit]

The Peerage, Engineering.com 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)[reply]

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)[reply]

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)[reply]

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)[reply]
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)[reply]
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 [2][3][4][5][6][7][8] 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)[reply]

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)[reply]

I've made the edit. SpinningSpark 08:13, 24 February 2014 (UTC)[reply]
-) (The first time in my life I've used one of those things, and perhaps the last.)69.253.215.129 (talk) 14:52, 24 February 2014 (UTC)[reply]

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)[reply]

When were his various electrical discoveries published[edit]

Not clear, as written, what was published/communicated before HC death, and what published first only much later by JCM. To make clear what influence/impact his work had. - Rod57 (talk) 02:25, 30 November 2015 (UTC)[reply]

External links modified[edit]

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G was not used since Newton's time[edit]

"The first time that the constant got this name was in 1873, almost 100 years after the Cavendish experiment, but the constant was in use since the time of Newton.[27] Cavendish's results also give the Earth's mass."

This is not true. Newton worked only with proportions and did not use constants like G which arise only if you use equations. The reference to Cornu and Baille is not justified since it is dated to 147 years after Newton. And the contents of the link is not available. I leave the link but take out the phrase "but the constant was in use since the time of Newton." Zeyn1 (talk) 18:11, 27 May 2022 (UTC)[reply]