I have a question about the article written by Isaac Asimov in 1987 that was published in the Los Angeles Times. It said

For instance, coal, oil, and gas all contain hydrogen atoms and you can obtain pure hydrogen from them, but it takes some energy to do this. You have to burn some oil to get hydrogen out of other oil and in this way, you end up with less fuel than you started with.

Is there anything that contains hydrogen that is not a fuel? Yes-there is water, the weight of which is one-eighth hydrogen. The only trouble is that ripping the hydrogen out of water takes energy.

(title: Quest for Fuel an Ongoing Objective, LA times (1987)),

Should I interpret this as meaning 'Yes-there is water, the weight of which is one-eighth of hydrogen'?

When you say that A is one-eighth of B, that means A=1/8×B, right? However, does this mean that water is lighter than hydrogen? Even though water is actually heavier than hydrogen.

  • 4
    Welcome to ELL, sukekiyo. Please edit your question to add a link to the article. If that is not available, please add the complete paragraph containing the sentence that you quoted, and also some information about the subject of the article. As it stands, it is impossible to answer your question without any context because, as you say, it doesn't seem to fit the facts. With some context, we may be able to work out how the confusion has arisen.
    – JavaLatte
    Apr 11 at 6:11
  • 6
    Water by mass is 8/9 oxygen and 1/9 hydrogen. The mass ratio is 8 oxygen to 1 hydrogen. This must surely be what Asimov was saying. The mass of hydrogen in a given amount of water is one eighth the mass of oxygen. Apr 11 at 6:49
  • 2
    sukekiyo - I don't understand the point of your edit. The original question was meaningful precisely because the typo caused the text to apparently be making an absurdly inaccurate claim. The difference between 1/8th and 1/9th is insignificant here, but that unwanted of makes it the difference between one eighth and eight times, which is clearly significant. Apr 11 at 15:05
  • 2
    @Fumblefingers Even without the word "of," I had thought that "there is water, the weight of which is one-eighth hydrogen" had the same meaning as "the weight of water is one-eighth of hydrogen." In fact, when I entered "there is water, the weight of which is one-eighth hydrogen" into a translation site, one of the candidates for the Japanese interpretation was "the weight of water is one-eighth of hydrogen."
    – user170674
    Apr 11 at 15:52
  • 2
    For a given amount of water, hydrogen accounts for one-eighth of its weight. Apr 12 at 2:03

4 Answers 4


The text is mistranscribed. The original says...

Q: Is there anything that contains hydrogen that is not a fuel?
A: Yes, there is water, the weight of which is one - eighth hydrogen

Crucially, there's no of before hydrogen (or possessive 's after it).

Asimov isn't saying that water weighs only an eighth as much as hydrogen - he's saying that one eighth of the weight of water comes from the hydrogen it contains - along with oxygen, one atom of which which is 16 times heavier than a hydrogen atom (but water is H2O, and 16/2=8).

EDIT: It's fully covered in comments, but in fact Asimov should have said that for any given weight of water, 1/9th comes from the hydrogen it contains (16 from one atom of oxygen plus 2 atoms of hydrogen gives 18, so hydrogen's contribution to "total weight" = 2/18 = 1/9). But this doesn't affect the syntax.

  • 5
    That's all "external" knowledge about chemistry and arithmetic (I knew someone would pick me up re "inaccuracy" in my final bracketed observation! :) But sticking to the relevant aspects of language, it's just a matter of an extraneous of creeping in. Apr 11 at 13:32
  • 6
    @MichaelHarvey: So you keep saying. But one eighth was good enough for Asimov to make his point, and it's certainly good enough for learners who want to understand the syntax. Apr 11 at 14:51
  • 3
    Maybe it's a foible of mine, but I am unhappy with numerical inaccuracy about simple things. If my grandfather left me one-eighth of his million-pound estate, and the executor decided to give me one-ninth instead, and said 'that's near enough', I'd be holding my hand out for the missing £13,888.89. I could get a nice little car with that. Asimov was a respected author of chemistry text books and a professor of biochemistry, so he's have known the right figures. Apr 11 at 15:14
  • 7
    In his essay "To Tell a Chemist" (1965), Asimov proposed a simple shibboleth for distinguishing chemists from non-chemists: ask the person to read the word "unionized". Chemists, he noted, will read un-ionized (electrically neutral), while non-chemists will read union-ized (belonging to a trade union). Apr 11 at 15:18
  • 9
    @sukekiyo I actually think even native speakers would have trouble with this if they had no knowledge of chemistry because it's not really obvious that there is hydrogen in water if you don't know any chemistry. But native speakers would have no problem with "there is my luggage, the weight of which is one-eighth books"...meaning that you've packed a lot of books in your luggage. Apr 11 at 22:00

It means that if you have x weight of water, then x/8 of that is hydrogen.

As you know, water is H2O — two hydrogen atoms for one oxygen atoms. Hydrogen's atomic weight is 1.008, while oxygen's is 15.999. So the total molecular weight of water is 1.008×2+15.999 = 18.015, and the composition of water by mass is:

  • Hydrogen: (1.008×2)/18.015 ≈ 11.19% ≈ 1/9
  • Oxygen: 15.999/18.015 ≈ 88.81% ≈ 8/9

So Asimov made an arithmetic error, apparently using 16 (the weight of oxygen) in the denominator instead of 18 (the total weight of the molecule). He meant to say “Yes-there is water, the weight of which is one-ninth hydrogen.”

  • 2
    You don't often throw your hat in the ring here on ELU - but when you do, it's usually solid stuff! I knew there was something not quite right about the arithmetic here (and I suspected the initial numbers weren't actually integers anyway), but you've definitely nailed the "numbers game" for me with this answer! The actual question turns on the significance of of in the cited text, which only really involves hypothetical confusion as to whether the underlying assertion is Water weighs 1/8th as much as hydrogen or 1/8th of water's weight comes from the hydrogen it contains... Apr 12 at 2:21
  • 2
    ...I'm content that I've covered the actual language issueds in my answer, but I like that there's a concise summary here of the exact measurable numbers and relevant arithmetic operations, for anyone who wants to dig that deep! Apr 12 at 2:26
  • 1
    @ilkkachu: I already a vague feeling that it's "integers to a great extent", rather than always exactly integers (which as ChatGTP has just informed me, is because of isotopes). And really that's why I expected at least someone to challenge the final assertion in my own answer. But I figured that was complicated stuff that many people wouldn't know anyway. On the other hand, I'm a bit shamefaced at having to admit that I didn't register the "1/8th or 1/9th" issue until it was pointed out to me (my only consolation being that Asimov himself seems to have made the same mistake). Apr 12 at 15:44
  • 1
    @dan04: Oh Lord! And there was me thinking I [almost] understood what was going on, once I grasped the isotopes business! But the truth is it's way past my pay grade! Apr 12 at 18:14
  • 3
    It's not just because of different isotopes, and the mass difference between protons and neutrons. There's also the nuclear binding energy, which makes the mass of a nucleus slightly less than the total of the masses of protons and neutrons in it. Apr 13 at 4:30

Adding because I don't see any answer saying this explicitly.

The word "one-eighth" in the sentence is acting as an adverb to "is" as opposed to the apparent assumption that it is acting as an adjective to "hydrogen".

So, think of it as:

The weight of water is mostly oxygen.

But, you replace "mostly" with "one-eighth" and oxygen with hydrogen.

So, the "one-eighth" describes the verb "is." It tells you that instead of you meaning "is fully," you mean only "is one-eighth."

  • This is the clearest substitute of all the answers. This helped me understood the syntax. Thanks
    – justhalf
    Apr 14 at 6:44

I think there is too much emphasis here on whether 1/8 or 1/9 is more correct; this is language, not science. The point is to understand his meaning; that a small fraction of water is composed of Hydrogen, but it's rather hard to get at, essentially not worth the effort.

I'm not sure how hydrogen cell batteries would fit into his discussion, but they essentially do the reverse: take oxygen and hydrogen, and combine them to produce water, electricity, and a bit of heat.

I'll throw in a little story, as a life-long (more or less) fan of Mr. Asimov: One morning circa 1992, I awoke with the oddest thought: "I wonder how Isaac Asimov is doing?" (Certainly nothing I had ever pondered before.) Within minutes, my clock-radio went off, and the two rock djs announced that he had passed away. (How these two djs even knew his name, I haven't a clue.)

You must log in to answer this question.