2

FADED

The brilliant reds in Vincent van Gogh’s paintings are slowly turning white. To understand how these Pb3O4-based red pigments degrade, chemists at the University of Antwerp, in Belgium, used X-ray powder diffraction tomography to study a sample taken from van Gogh’s 1889 painting “Wheat Stack under a Cloudy Sky.” The white circle on the painting indicates the spot that they sampled. In the space between the sample’s reddish-orange Pb3O4 core and the light blue PbCO3 layer that surrounds it, the chemists found plumbonacrite, 3PbCO3•Pb(OH)2•PbO. The chemists propose a mechanism of how red lead degrades via plumbonacrite, involving carbon dioxide and light.

Adapted from C&EN, March 16, 2015, p. 26. - Van Gogh’s Red Is Turning White

Seattle Shows Us Exactly How You Should Treat Drug Offenders

Seattle’s Law Enforcement Assisted Diversion program (LEAD) has taken hold of the neighborhood in the past three years. Instead of sending a low-level offender to jail, the officer can offer the offender the option of taking them to the precinct, having them meet with a social worker, and becoming part of the LEAD program. From there, the offender’s crime is taken off the record, and they can take advantage of existing low-income assistance programs. Case workers work closely with the person to help them find housing, help them get health care, and generally support them in making life changes.

Lead ingot, presumably medieval, found in Østfold. It has a thin line engraved around the object 5-6 mm from the bottom, and seems to have had the same line where it is cut. It has equal marks on two sides, indicating that it has been held with pliers or another tool. We map the area among other things to determine whether there has been handicraft production there in earlier times, so it is an interesting find. Production of weights is a possible explanation, especially since the selected part will weigh about 1 ørtug, which is an old norse weight unit.

24x15x13 mm, and 30.6 grams