欧美日韩国产ⅴA另类_手机福利久久日韩手机看黄片_外国一级av超碰我在线人人_午夜91人妻久久_无码免费视频看国产a一区_久久无码国产草泥马_玖草在线视频人人操国产_成人无码区免费AV片久久

Usage of glass distillation unit: clean the instrument and fix it with iron frame. If the bottom of the flask is heated by gas or electric furnace, an asbestos net shall be padded, and the volume of the liquid put into the flask shall not exceed 2 / 3 of

Ordinary distillation has bubble and boiling phenomenon, while molecular distillation is the free evaporation on the surface of liquid film, with low operating pressure, generally 0.1-1pa order of magnitude and short heating time. Generally, it is only te