Friedrich Wilhelm von Hoven, the head of all the hospitals in Nuremberg in 1835, wrote a series of essays attacking the practice of homeopathy which was all the rage in elite circles in Germany. The response from homeopaths was a challenge to trial the therapy: try a C30 dilution of salt.

A C30-dilution is a single crystal of salt in 100 parts of water, then diluted 1:100, 29 more times. Statistically, it contains none of the original substance. An ad in the local newspaper yielded 120 volunteer participants who met at a local pub.