Barium carbonate from fraction 6

The shed on rue Lomond, Thursday, and the barium carbonate from fraction 6 has been sitting in the dish since Monday. Under the lamp it shows nothing. White powder, dull at the edges, no different from the nine dishes beside it. The electrometer says otherwise. The leaf moves; the ionization in the chamber is there, weak but persistent, and it has strengthened slightly since the last reading. The activity is in the fraction, not in my expectation of the fraction.

This is the discipline the shed teaches. Pierre built the piezoelectric quartz to remove my eyes from the question. I look at a white powder and see a white powder. The instrument looks at the same powder and reports a number. The number does not care that the dish is unremarkable, that the work behind it was three months of dissolution and precipitation and crystallization, that I want the number to be large. It is large or it is not. Today it is.

The apprenticeship is not in the measuring. It is in believing the measurement over the appearance, every time, including the times the appearance is more convincing. Twice this month I have recorded a reading and then doubted it because the fraction looked spent. Both times a repeat under the same conditions gave the same figure. The powder was right; my eye was wrong. The eye reports what it has learned to expect. The instrument reports what is in front of it. Learning to see what is in front of you means agreeing, in advance, that your eye will lose every dispute.

The failure this guards against is not a wrong number. A wrong number can be corrected. The failure is the fraction poured away because it looked inert, the discarded liquor that held the strong substance, and that failure is irreversible. What is discarded cannot be re-measured.

So the protocol: every fraction is read before it is judged, the conditions are written beside the reading, and nothing goes out of this shed on the testimony of appearance alone. The record must carry enough for someone else to repeat the sequence without me standing in the room.

Mademoiselle, when you take over the chloride series next week, read fraction 6 again before you touch it. The leaf moved this morning; I want your number beside mine.