What is this piece of glassware called?
The picture shows parts of an arsine generator.



The apparatus can be used to determine trace amounts of arsenic by the silver diethyldithiocarbamate photometric method. 

A typical method description can be found here (this is also the source of the drawing):

https://hmc.usp.org/sites/default/files/documents/HMC/GCs-Pdfs/c211.pdf

or

http://hmc.usp.org/sites/default/files/documents/HMC/GCs-Pdfs/GC_pdf_USP38/c211.pdf