ON A shelf sit three jars of peanut butter labelled “not for human consumption”. But they are no ordinary supermarket items. These jars cost over $140 each and occupy a very special place in the pantheon of everyday objects – they have been studied with the greatest of precision.
Not only are they of a precisely known weight, they come with a complete list of constituents measured as accurately as possible by the US National Institute of Standards and Technology (NIST). This all-American food is the most recent and final addition to the NIST’s set of standard reference materials (SRMs), which…
