Actually, if you want to know the miraculous effect of this elixir and what kind of elixir it is, the method is simple: just eat it to see the effect.
But there is only one of this elixir, once it's eaten, it's gone. It would be such a pity if it could grant immortality or allow ten times a night, and it's gone after consumption.
When Song Xiaodong saved Zhang Dongfang's father-in-law's life, he used one elixir, and maybe since then, the old man got interested in them and got this elixir from abroad.
Who knows where the old man found it.
Song Xiaodong thought, why not, just like when he tested the ginseng whiskers in Beijing against Zhang Yanran's Appraising Master, pick a piece off the elixir to taste and see what miraculous effect it could have.
No sooner said than done, Song Xiaodong tried to scrape it with his fingernail, but it wouldn't move at all.
So Song Xiaodong took out a silver needle and poked the elixir twice, yet the smooth surface did not even show a trace.
