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[Music]
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hi guys
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uh welcome to my channel in this video
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i'm going to discuss with you
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three important experiments of class
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11th chemistry which are done that is
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cutting a glass tube
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uh bending a glass tube and drawing a
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jet so you can just follow the
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instructions
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uh look for all the precautions listen
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carefully
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and then go to your school labs to
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practice the same so let us begin
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so our first experiment is cutting a
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glass rod
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of length 10 centimeter right so
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the first thing to check is i will take
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a smooth end
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uh i'll feel this end of the glass rod
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this is a smooth end so i'll start from
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here and measure
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10 centimeter from here using a scale
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and mark that end with the marker
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so i'm keeping
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this here and 10 centimeter i'll make a
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mark
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this is a 10 centimeter mark and now i'm
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going to make a cut here
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using this triangular file this is a
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triangular file
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it is wedge shape it has these three you
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can see
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uh surfaces with
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this is a rough surface like a sandpaper
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so
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we can use this surface to rub and
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smoothen
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a particular end okay if your end is not
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smooth if the end of the glass rod is
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not smooth
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it can be rubbed like this with this
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file to make it smooth
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okay so now i'm going to make a hold the
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glass tube
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very firmly with this
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finger and thumb not excess pressure
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neither too lightly
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and hold this file this way and make a
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one
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strong scratch one strong scratch
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in case you feel one is not strong
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enough you can repeat
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one on the same point this scratch
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should not be
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too strong otherwise this glass tube
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will crash or break
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and you will not give it repetitive
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scratches also
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there should be a strong scratch at one
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point and now i'm going to
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hold this between these two hands
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this is the scratch point i'll face it
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away from me
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keep the thumb and finger and just with
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the soft pressure break it and i get
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these two two halves this is a 10
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centimeter
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uh tube and i will feel the
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ends the ends are smooth in case they
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are not
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as i told you you can rub it or
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we can do fire polishing fire polishing
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is heating it in the
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flame fine you can fire polish the end
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like this
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fire polishing means i'm going to heat
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it in the flame
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so that the ends get rounded you study
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this fire polishing
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in your theory as well in liquid state
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chapter
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so i am just going to rotate this in
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flame
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and the end is rounded
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the end gets rounded right and smooth
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similarly if the other end is also
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not smooth i can heat it in the flame
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keep rotating so as to
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smoothen that end
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and please be careful
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cool the tube before you handle it
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in between two such steps so i have fire
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polished means i've
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rounded the edges and this is a
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glass tube with 10 centimeter length
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cut right
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so you can observe this is a 10
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centimeter long
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tube plus tube cut right now
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we will discuss how to bend a glass tube
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at an angle of 90 degree
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why do we need to bend we generally bend
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glass tubes to create delivery tubes
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so let us go ahead so this is a glass
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tube i have taken a glass tube
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right and this is the long glass tube
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i'm going to bend this last tube at an
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angle of 90 degree
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at an angle of 90 degree so just say
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i'm going to heat this at the point i
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want to bend
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with constant swirling in the
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non-rivenous part of the flame
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i'm going to heat this constantly like
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this
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and the moment it feels soft
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and please see that you focus heat at
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one point
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only you don't let heat move
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and now bend it to an angle of 90
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i'll check the angle by putting it here
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and as still hot i can set the angle
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this is a 90 degree angle i am checking
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it across the edge of this
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tile the surface okay and now let it
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cool
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this is your bent glass tube
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so i'm showing you another glass tube
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again and telling you the precautions
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the first precaution is you should keep
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swelling like this
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the second precaution is
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the second precaution is when you have
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to bend it
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you will only turn one hand not
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both you will not turn both hands in
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only one keep one fixed and with
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one see i'm just turning one with one
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without any shaking like this there
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should be no shaking
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because if there's a shaking there will
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be a kink at this point this
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point might get blocked so there should
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be no shaking of hand
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uh you will not move see you will not
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move both the hands like this
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you will keep one hand fix and just move
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one
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right this is going to give you a very
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neat clean bend
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so this was bending a tube and now we're
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going to proceed with how to draw a jet
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how to draw a jet from a glass tube so
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again i am taking a glass tube
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and heating it in this non-luminous part
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of the flame
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with constant swirling
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and the moment it becomes soft
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i'll pull the two ends apart
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see it has become soft and now i'm going
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to pull the two ends
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apart right and
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let this end cool and now depending
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on depending upon how much
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size bore i want what is the size of the
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hole i want at that end
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i will be making a cut on this
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so i'm going to make a cut with this
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wedge
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and depending if i want a bigger hole
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i'll cut it towards this end
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if i want a smaller hole towards the tip
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and then i can
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fire polish this end to smoothen this
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end
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i can fire polish to smoothen this end
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and this is a jet
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prepared so i'll show you uh how this is
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working like a jet see i'm going to
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pour water into this
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and uh you can see
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this is now working like a jet
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so you can see this is behaving like a
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jet
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i'm sharing with you how to write down
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the
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cutting bending experiment in your copy
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this is the right hand side page
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you will write down to cut a glass tube
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of 10 centimeter length
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and then the procedure and then the
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precautions this is to be written on the
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right hand side
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page on the left hand side page again
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aim
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apparatus used
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and diagrams this is the next experiment
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to bend a glass tube at an angle of 90
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degree
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again writing aim procedure
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and precautions
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this is the left hand side page
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aim apparatus
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diagrams
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this is the third experiment to draw a
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glass jet
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again aim
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apparatus
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diagram
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and this is the right hand side page