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Schlenk: Handling of Solids
If a solid compound of a reaction is air stable it can be weighed under ambient conditions. To fill it into an inert gassed flask, a special cone is used, which has a straight end, that fits well into the joint, so the compound won't stick to the grease. The valve is turned to inert gas. Removing the plug and adding the cone, the compound can be filled in on the counterflow of inert gas. Afterwards the flask is evacuated and gassed several times to remove remaining oxygen, which stuck to the solid. This can't be done with solutions and liquids, because they will evaporate into the vacuum or expand into the line.
If an air sensitive compound shall be filled from one flask to another, a male to male glass joint is required. The joint is greased, plugged into the flask turned around to ensure it is air-proof and secured with a clamp. On the opposite side, a dummy-flask is placed. This setup is evacuated and gassed three times. Now the dummy flask is removed and the solid-containing flask is combined with the joint in the counterflow. Again its turned around and secured with a clamp. Now the solid can be transferred by turning the setup around.
Often solid grains stick to the grease. So it's advised to solve a solid compound first and transfer it via a syringe, a dropping funnel or a perfusor.