i think this is a more chemiical enginerring question so i'm afraid i'm neither use nor ornament on this one ...
boards.straightdope.com/.../t-97431.html

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Note added at 6 hrs (2011-11-28 11:45:29 GMT)
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Подразумевается, что от меня в данном конкретном случае мало толку.

Взятки гладки (coll, often disapproving) means it is futile to attempt to hold somebody responsible for something or get something out of him or her (because of their character traits, attitude, circumstances, financial situation, etc.). c X-а взятки гладки could be probably be rendered as you (he etc.) won't get much <anything> out of X; you won't get anywhere with X; you're wasting your time on X; there's nothing you (he etc.) can do to X; X cannot be called to account; [when somebody cannot be blamed or punished for something because his accusers lack proof] you've <they've etc.> got nothing on X

Getting anything out of him is like squeezing blood out of a beet (or a turnip). One (You) cannot draw (or get) blood from a stone. You can't force his (her) hand. You can have no more of a cat but (or than) her skin. (CONTRAST: To get some mileage out of smth. Cf. С паршивой овцы хоть шерсти клок).

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Note added at 606 days (2013-07-27 00:03:07 GMT)
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Жаль, что примеры не вместились в поле. 1. В соответствии с законом "О защите прав потребителей" заказчик может потребовать с ателье неустойку за каждый день просрочки. Но если он сам окажется забывчивым и будет месяцами держать свою вещь в ателье, с него взятки гладки. - The Customer Rights Protection Law says that a customer has the right to demand from a Tailor House the forfeit money for each day of delay. But if the customer himself is forgetful and will not take his garment from the House for months, his hand cannot be forced.
Поезд опоздал? Проводник спал всю дорогу? Ничего не поделаешь. Тут с железной дороги, как говорится, взятки гладки. - What if the train was late? What if the conductor was asleep all the way? It can't be helped. To make the railway authorities liable is like squeezing blood out of a beet.