COLOUR CODING OF MEDICAL GAS CYLINDERS

(1)"Oxygen : Black coloured with white shoulders", while ur walking thru the Casualty of any hosp u'll find this holstered on the bars beneath a stretcher.
(2) "Carbon - Dioxide : Grey Colour" just try writing Carbon diaxoide chemical formula on a paper i.e. CO2 , putting 2 as subscript of O, you'll notice that the O and the 2 form a lowercase "g" designating CO2 :-> C for CarbonDioxide and O2 for g i.e grey
(3) " Air : Grey body and black valve" just think of the hAIR on our head, its black first and then turns grey, similarly the valve is black and the body below the valve is grey.
(4) " Nitrous Oxide : Blue" this is damn easy, if you've watched the Movie Housefull (Akshay,Ritesh, Lara, Deepika), recall the last seen where there is a switch of cylinders at the Queen's Royal Palace Gathering and the 2 goons end up connecting the wrong tank flooding the reception with Nitrous Oxide , giving the laughter riot at the end of the movie because, Nitrous Oxide is Laughing Gas.
(5) "Cyclopropane : Orange" well orange is a fruit which is rich in Vitamin C and the name Cyclopropane starts witha C, so C for Vit.C is as to Orange is as to Cyclopropane.
(6) "Ethylene : Red" Well in PUC biology we had learn't the reason behind the one-liner "a few rotten apples spoils the entire lot" lets say the few rotten apples are at the bottom of the basket , when fruits and vegges are spoilt they release "Ethylene gas" which travels up and spoils the apples which are "RED" in colour causing them to inturn release the gas hence Ethylene "->Red.
(7) "Helium : Brown" I am a big fan of brownies and recently i wanted to learn how to prepare them by myself, so i googled and founf out that the easiest Brownie to prepare is the "Float Brownie" (you too can google) now what makes the baloons float, yes its Helium, So Helium: Float :: Float Brownies : Helium :-> Brown
(8) " Entonox : Blue body with Blue Quartered Shoulders" very simple what was the 2World cup frenzy, yes it was "BLEED BLUE", to bleed blue for the men who wear blue clothing on their body with blue clothing on their shoulders, now if we have to bleed blue it means we have blue "WITHIN" us and what does ENTO mean in greek, you guessed it right, it means within, For Ex. Entropion (Ento-ro-pion) meaning the eyelid folds within or eyelid folds inwards, hence, Entonox is Blue Body with Blue Shoulders.
(9) "Halothane: Amber" I'm a fan of Halo, in Halo2 while playing the Delta level the music is In Amber Clad, its gotta quite good tune to it (type '"In Amber Clad (extended) - Halo 2 soundtrack' on you tube to listen to it) Hence HALOthane :-> Amber. 
Moral of the story " What the mind does not know, the eyes do not see" if your mind knew that medicine existed everywhere then your eyes would by default see it and help you in crisis times.