(photo of the U.S. Radium Corporation, a major supplier of luminous watches to the military during world war one)
The Presence was spectrum-blue,
ultimate blue ray,
rare as radium, as healing;
“Spirit” had announced the “Presence” in section , and the emergence of the Voice (or H.D.’s reclaiming of the sites of hearing thru which the “Voice”, which is always already there (“eternity endures”) can be heard. The presence being “spectrum-blue” and “ultimate blue ray” returns us again to section  amidst the “mist and mist-grey, no colour” of war, where, in “unalterable purpose”, we find ourselves in “green, rose-red, lapis” and now, “ultimate blue ray.”
As far as the mention of “radium” in this section, there is interesting backhistory that gives this reference weight. First, some small things: radium has the symbol “Ra,” which will come into play in section . Radium is found in trace amounts of uranium ore, and when prepared, its color is brilliant white with a luminescent blue glow.
Radium was discovered by Marie and Pierre Curie in 1898; she actually coined the term “radioactivity” (regarded as a natural force that would lead to insights into the structure of matter, and to applications in medicine and science). While the Curies were working to extract radium, the chemical’s bluish glow captured the public imagination. Companies in the U.S. began mining it and selling it as a novelty: glow-in-the-dark light pulls and cure-all medicines (that actually killed people).
Wristwatches with radium-painted luminous dials became an overnight fad. The Radium Luminous Materials Corporation opened in 1917 in N.J.; other companies opened plants in Connecticut and Illinois. Several million radium watches, clocks, and instrument dials were made through World War II.
The glowing numerals had to be hand-painted; the workers (mostly young women) painted about 250 dials a day for a cent and a half apiece. Within a few years, many of the women died from radiation poisoning. Until sometime in the 1920’s, the women used a technique called “lip-pointing” (they used their lips / tongues to shape the paintbrushes). They often went home so coated with radioactive paint dust that they glowed in the dark. Some, unaware of the danger, painted their lips, teeth, eyelids, fingernails and the buttons for fun.
The dial-painters’ first health problems turned up in the 20’s. In many cases, their bodies were actually radioactive, because radium had been absorbed by their bones (radium acts similar to calcium and the body mistakes it for calcium and absords it into the bone).
[this info is from wikipedia & the article “A Glow in the Dark, and a Lesson in Scientific Peril,” by Denise Grady, Oct 6 1998, The New York Times). a related book: by Claudia Clark, “Radium Girls” (University of North Carolina Press, 1997)]
When I return to the top of this post to read the short passage again, the effect of this history infusing the “spectrum blue” has a striking effect. It is, as H.D. notes, “indelibly stamped.” The poem, however, doesn’t end there:
my old self, wrapped around me,
was shroud (I speak of myself individually
but I was surrounded by companions
in this mystery);
do you wonder we are proud,
indifferent to your good and evil?
This comments on the use of the word “proud” in the previous section. But i am honestly surprised that H.D. claims the poet is “indifferent to your good and evil.” Maybe the key word there is “your” – that these moral codes have been established by those who do not hear the Presence of the Voice, of those who deny the value of “old wisdom. This abandonment of the “old values” from the current valuations of good and evil have created:
peril, strangely encountered, strangely endured,
we know each other
by secret symbols,
though, remote, speechless,
we pass each on the pavement,
at the turn of the stair;
though no word pass between us,
there is subtle appraisement;
even if we snarl a brief greeting
or do not speak at all,
Peril, War, Radium has marked us. We glow with our poisoning. The secret symbols and the watch dials. Ra. Thru all the pain we have encountered, all the tragedy, we endure. The poison in our bones. The bone frame holds. and
we know our Name,
we nameless initiates,
born of one mother,
of the flame.