Hard to believe that even in Meiji Japan they used chloroform, or a drugged soaked cloth. It's an alright scene, exemplified by the fact that they show the cloth in Enishi's hand in retrospect.

 

         This scene is featured in the Rurouni Kenshin OAV Seisouhen (I have a clip of it on my clips page). I lifted the scans from Spectrum Nexus. The interesting thing is that Seisouhen had two chloros of Kaoru. I do not know if the first chloro was in the manga. Here is an interesting story on how I came across this complete scene. I had the first scan for a really really long time (Feburary 2005). The problem is I never recorded which volume the scan came from. Recently I wanted to figure that out for indexing purposes but it was hopeless. I went on Spectrum Nexus and I was flooded with a sea of scans. I looked into volume 24 and just randomly clicked on a scan. That scan just happened to have the panel where Enishi is holding a cloth in his hand (the third scan above). I was SO LUCKY! It was totally random and yet I found the scene. And then I found Captain America #103 and icon7 posted a chloro from Samuree #8. I was about to have a freaking heart attack!!!!   

Scenes I recently indexed for chloroform were Captain America #103, Lois Lane #61 (updated that one), Lois Lane #84 (check out that hilarious scene where Lois chloroforms Superman) and of course Samuree #8 (icon7 you are a God).

For sleeping gas I indexed a scene from Detective Comics #404, damsel is Batgirl. Check it out.