What is this piece of glassware called? Here's an image:



The left side is designed to be fitted into a beaker, and it captures gas evolved during a reaction.  The right side can be filled with a liquid to then react with that gas.  We use it to capture ammonia from a decomposition reaction, with an indicator in the right half as part of an identification test.  I'm sure it must have a name, it's a commercial piece of glassware, but the box we keep it in in the lab doesn't identify it.
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