Avodah Zara 72: Acquiring and Pouring Wine; Connecting Objects through Streams of Liquid

Some brief notes on today's daf:

• when does acquisition take place for a Gentile?
• was the wine measured out before or after the money was exchanged?
• where did the transaction take place?
• who was participating and when? 
• can people use wording carefully to renege on an agreed price?
• must all of those who provide estimates agree on the final product?
• A mishna states that if a Jew took a funnel and measured wine into a Gentile's flask and then into a Jew's flask, a drop of wine might stay in the funnel and thus the Jew's flask is forbidden. If one pours from one vessel into another, the wine left in the top vessel is permitted and that in the bottom vessel is forbidden
• The Gemara quotes a mishna that teaches that a number of liquid transfers are permitted as they are not 'touching': nitzok, a stream of water falling through the air; tofe'ach, something wet enough to wet a hand that touches it; letamei, if the bottom is tamei and the top is tahor; letaher if the top is tamei and the bottom is tahor. 
• ashboren, a collection of water, is considered to be connected and both letamei and letaher
• the drop of liquid is forbidden because of nitzok - pouring into the Gentile's dirty vessel connected the funnel to drops of grape product at the bottom of the vessel
• is the wine that is mid-air permitted or forbidden? The rabbis argue this point in detail
• Rav Chisda teaches wine sellers to interrupt the flow or throw the wine from far to a Gentile's vessel so that a stream will never connect the vessels
• Rava teaches people who pour wine to take no help from Gentiles because he might pour alone, leaving his wine forbidden to him
• the rabbis discuss a case where wine was syphoned from a barrel using two connected reeds in an arc when a Gentile put his hand on the bottom and stopped the flow - Rava forbade all of the wine