instruments of crime. The seller, for example, might be required to enter in a register the exact time of the transaction, the name and address of the buyer, the precise quality and quantity sold; to ask the purpose for which it was wanted, and record the answer he received. When there was no medical prescription, the presence of some third person might be required, to bring home the fact to the purchaser, in case there should afterwards be reason to believe that the article had been applied to criminal purposes. Such regulations would in general be no material impediment to obtaining the article, but a very considerable one to making an improper use of it without detection.

The right inherent in society, to ward off crimes against itself by antecedent precautions, suggests the obvious limitations to the maxim, that purely