Abstract: A first aspect of the invention involves placing a pair of parallel, spaced apart sealing septa in each channel of a reactor block through which materials are added to or removed from a reactor flask such that the septa enclose a cavity within the channel. A hole is formed through the block to intersect the cavity and is connected to a source of low pressure, substantially non-reactive gas which acts to prevent materials from leaking through a hole in either septum. The reactor flask is formed of glass as a substantially conical chamber with a first tube and a second tube connected to the flask perpendicular to its axis. The second tube extends within the flask so that its interior end resides proximate the opposite interior surface of the flask. The second tube terminates in a glass frit being permeable to certain of the chemical materials in work and non-permeable to others so as to act as a filter.