Chloroform has been used as an anaesthetic. I read somewhere that Queen Victoria used chloroform while giving birth to one of her children since it eased the pain.
Here is an interesting article on its medical use
- simple enough for laymen like me.
However, according to an article on the criminal use of chloroform, its use by robbers and kidnappers is more legend than fact. It requires a certain amount of expertise in order to get the right dose to knock out a victim without doing considerable damage to his health or even killing him. Also, even for an expert anaesthetist working in a hospital, it can take up to five minutes to actually render a patient unconscious using chloroform.
Thus, if you tried to use it in order to rob someone, chances are that the victim will be able to fight back long before the chloroform has had any effect.
There have been cases of doctors being accused of using the stuff in order to commit sexual assault, but apparently it was very difficult to prove in court that chloroform was actually used.
The scene in "Black Island" may be possible: without doing the research I'm assuming that a large amount of chloroform from a bottle combined with the heat of the burning house could have knocked Tintin out.
On the other hand, the scenes in "Unicorn" in which Sakharine and Tintin are put to sleep by chloroform are unlikely.