A mineralogist at Besançon had just sent us a collection of siliceous nodules, which I had to classify: so I set to work; I sorted, labelled, and arranged in their own glass case all these hollow specimens, in the cavity of each of which was a nest of little crystals.
Precisamente, daba la casualidad de que un mineralogista de Besanzón acababa de remitirnos una colección de geodas silíceas que era preciso clasificar. Puse manos a la obra, y escogí, rotulé y coloqué en su vitrina todas aquellas piedras huecas en cuyo interior se agitaban pequeños cristales.