Murder most foul?

This morning I came across this broken, blue-glass bottle out among the sand dunes.

Back in the 1800's, poisonous substances were stored in bottles made with distinctive features so as to prevent unfortunate accidents. Colours such as cobalt blue, inky black, and dark green ensured they were easily recognisable. To help prevent mistakes, when fumbling for the medicine bottle by candle-light, the bottles were often embossed with the words 'POISON' or 'DEATH', deep grooves, geometric shapes, or the skull and crossbones.

Now what was this little blue, ribbed poison bottle doing out among the dunes, far from human habitation? Had I stumbled across the scene of a dastardly murder back in the mists of time? Had there been a picnic, where some cuckolded husband had slipped a dose of arsenic or strychnine into the tea of his rival, or that of his unfaithful wife, thus ensuring a painful death? Or perhaps it was a young wife eager to see the end of her rich husband? We shall never know!