Taxidermy got its great leap forward in the mid-eighteenth century with the innovative chemical experiments of Jean-Baptiste Bécoeur, a French pharmacist and naturalist from the town of Metz in north-eastern France. In 1738, Bécoeur began experimenting with 50 different chemicals to determine which were most effective against insects. He tested one chemical on 50 different specimens, leaving the birds exposed to any type of hunger worm or mite or fly which might be passing by. After four years only four specimens were free from insect attacks. He decided to mix these four chemical – ground arsenic, camphor, potassium carbonate, and powdered calcium hydroxide - together with soap in a preparation which has become known as arsenical paste.
After years of tests and trials, failures and eventual unparalleled success, Bécoeur was keen to trumpet his success but loath to divulge his secret preparation. He resolved to send several of his specimens to the most distinguished collection in France, the Muséum d’Histoire Naturelle in Paris, where hopefully the excellent quality of his birds would publicise his remarkable achievement. His decision was inspired. The renowned naturalist Buffon, the museum’s director, was more than impressed as were all the museum’s visitors who were shown Bécoeur’s birds as exceptional examples of taxidermy. Where most specimens only survived several years unless sealed airtight behind glass, Bécoeur’s survived in the open air. Buffon wrote to Bécoeur in 1758 not only to inform him that all the birds were still “in excellent condition” but also requesting more specimens. Despite everything, Bécoeur went to the grave without divulging his hard-earned secret.
Bécoeur was himself an avid collector of birds, animals, and insects, and established a notable collection which purchased seven years after his death by Karl III August Christian, Duke of Pfalz-Birkenfeld Zeibrücken (1746-1795). What happened after that is somewhat of a mystery. Bernardin Pierron visited soon after Bécoeur’s death:
Had Bécoeur lived in ages past, he would have been accused of witchcraft and enchantment. What wonders has this excellent naturalist not been able to unite in his cabinet. These are truly immortal animal. The dog barks (or so it seems), the monkey changes posture, tile hedgehog hides below its spines, the timid hare lifts its ear to listen, the sloth fears to move in search of food …. The birds soar or play with their feathers painted in a thousand different colours. They are marvelously assorted in the bird of paradise, which has a golden head, a green collar, a bright red back and wings equal to the rainbow in beauty; yet it is not inferior to the humming-bird whose lively brightness surpasses all masterpieces of art. The feathers of the cock-of-the-rock seem to compete with the first rays of dawn. The toucan with its curved beak, the cardinal, the American blackbird - but I would struggle in vain to mention all the birds, which Bécoeur assembled.
The envy which follows all great men could not leave Bécoeur alone; but the cloud will soon pass. The flame of truth will dissipate the clouds of the lie; posterity will do justice to the merit of this great naturalist. Paris will bemoan, when it is too late, that I never took the service of this estimable citizen."
Bécoeur was unwilling to publish the recipe for commercial reasons and succeeded in keeping his formula secret during his lifetime. However, the formula was eventually popularised by French taxidermist named Louis Dufresne (1752-1832) in 1820.