After returning from South City, Ran Yan began to carefully recall all information about asthma and meticulously recorded it. Meanwhile, Liu Qingsong was primarily responsible for searching for patients with asthma in the streets.
The poison Ran Yan developed, through continuous improvement and perfection, after numerous in-vivo experiments on rats, finally achieved a fairly ideal effect. It minimized the occurrence process and the traces on the corpses to the lowest level, if modern techniques were to be used to examine cell slices, one would definitely find clues, but in the Great Tang, even Ran Yan herself had no better method of verification.
As for the means of poisoning, Ran Yan had also considered many.
