To give Emily Dickinson her due, one of my favorite poems by her is #510:

          It was not Death, for I stood up,
          And all the Dead, lie down--
          It was not Night, for all the Bells
          Put out their Tongues, for Noon.

          It was not Frost, for on my Flesh
          I felt Siroccos--crawl--
          Nor Fire--for just my Marble feet
          Could keep a Chancel, cool--

          And yet, it tasted, like them all,
          The Figures I have seen
          Set orderly, for Burial,
          Reminded me, of mine--

          As if my life were shaven,
          And fitted to a frame,
          And could not breathe without a key,
          And 'twas like Midnight, some--

          When everything that ticked--has stopped--
          And Space stares all around--
          Or Grisly frosts--first Autumn morns,
          Repeal the Beating Ground--

          But, most, like Chaos--Stopless-cool--
          Without a Chance, or Spar--
          Or even a Report of Land--
          To justify--Despair.

Of Dickinson's 1775 poems, 42 begin with the word 'It' or 'It's'; another 14 begin with ''Twas.'  And the 'it' is almost never an explicative anticipating a nominal that will make explicit what the 'it' refers to.  No, it's a personal pronoun (those of us who are English teachers would write "unclear reference" in the margin) that Dickinson is going to struggle to define.  When she's successful, it's not that the reader will leave the poem with a clear sense of the pronoun's reference but rather will have briefly and intensely experienced the "zero at the bone" that is so often both the subject of and the response to her poetry.

The first two quatrains rule out four possibilities, symmetrically balanced with two lines each.  Dickinson begins with the most obvious choice, death, but eliminates it on what seems the most trivial of grounds: the dead lie down (in coffins, in graves), but she is still standing.  And then comes night, and the poem begins its darker shift.  As so often in Dickinson's work, she reverses or twists the standard poetic device of personification.  While the human personae in her poems are often mechanized or inorganic ("marble feet" in the second quatrain), the non-human world is personified, but in a grotesquely startling way; here, the bell's metal clapper becomes a tongue--a tongue that's being, as it were, stuck out at the world.

In stanza two, Dickinson rules out frost (again the hot winds don't blow or waft, but crawl) and fire.  Her feet are reduced to marble, and they alone could keep the entire front of a cathedral, where one might find marble statues of the saints, cool.  The persona may not be dead, but she is already like a memorial statue.  Still, 'cool' is hardly the word one wants to apply to her emotional state.

In 105 of her poems, the shift (usually at the exact mid-point; here earlier) to the darker tone is signaled by the word 'and.'  (In 84 more, the turning point comes with the word 'but.')  Here with 'any yet,' the poet tries a different strategy for defining her subject: having ruled out four possibilities, she now suggests comparisons based on taste, of all the senses the one most associated with fear ("I was so frightened I could almost taste it").  But unlike the balance in the first two quatrains, here death gets seven lines; night, three; frosts, two; and fire is squeezed out altogether.  The comparison with death begins calmly, if trivially: recalling the first two lines, the persona now realizes that the dead do sometimes stand, when they're set on end in preparation for burial.  And then, more eerily, it's as her life were shaven and fitted to a frame.  Don't they normally shave the planks of the coffin to fit the body?  And worse, it's as if she couldn't breathe without a key, as if she's been buried prematurely.  (Imagine how hysterical Poe would be at this point.) 

And then it's like night (indeed, like midnight).  The earth, once more less organic than mechanical, no longer 'ticks."  Space, as happens more than once in Dickinson's poems, is dispassionately observing her--more than observing 'staring' as if at the scene of an accident.  When morning comes, it's the morning of autumn and of frosts, which 'repeal' the once beating, then ticking, now silent ground.  'Repeal' both reminds us by its sound of the bell in lines three and four and more strongly suggests, for what are most commonly repealed but laws, that the laws of the living natural world are no longer operative.

And finally in the last stanza, the comparison becomes more abstract: the 'it' is like Chaos.  It's 'stopless' and 'cool,' now used quite differently than in line eight.  And finally a metaphor for the simile.  The chaos is like a ship lost at sea.  For Crane in "The Open Boat," the ultimate irony of the potential death of the four men at sea (and the actual death of one of them) is that they are so close to land that they can see the shore, the life-saving station, the people on the beach.  The irony is quite different in Dickinson.  If there were a chance or if the boat had a spar or if there was even a report of land (to say nothing of an actual sighting), then a precise emotion--despair--would be justified.  But here there is nothing even to despair of.

Negation and simile haven't made the 'it' any more precise.  They have, however, demonstrated to and perhaps even created in the reader Dickinson's persistent emotion: zero in the bone.