"Ribonuclease II. Accuracy of measurement and shrinkage."

Date:
1954-1955
Reference:
PP/CRI/H/1/32
Catalogue details

Licence: In copyright

Credit: "Ribonuclease II. Accuracy of measurement and shrinkage.". Source: Wellcome Collection.

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    counts in ten seconds were initially with cold jet 809 4300 5300 8/0/TS 3700 1600 If the jet were now turned off the intensities would return to their original values, or ones close to them, with a time-constant of, say, -few©—to go two-thirds of the way. If the jet were now turned on again the behavior could be repeated. Measurement of the cell dimensions showed that the cold jet caused them to decrease slightly. Because of this, care was always taken to set accurately on the reflection being measured on each occasion. A small jet of air played through the collimator onjto the capil lary in the neighborhood of the crystal could produce similar effects, MVi Ê-*U>»tA.-»vofc ÍW although its temperatu: erá# from room temperature by ae—H-ttt« •ss, l°C. The direction of the effect depended on the position of the crystal in the capi 1lary with respect to the jet. This could be studied by measuring 809 and 8^0^10 instead of 80§ and For one crystal it was found that under favorable circumstances ' 2- the tntensity of 8^0/ÍÜ could be reduced by a factor of -Ute by the heat of a hand held for a minute or so 4 or 5 inches aw-ay from the capillary on the side nearest the crystal. The effect was repeated a number of times. The effects can also be produced by the general conditions of the X-ray room. (This is fed by an air-conditioning plant which keeps C the temperature not far from £5°C. Otte to this, and to the fans of the cooling systems of the X-ray units, there is a considerable movement of air in the room.) These effects were in fact first ^