It's a British WW2 SOE Limpet AC Delay mechanism. OFS got closest (and essentially correct) when he said "Acid ampule from a time pencil" though Eric's "Acid ampule from a mine" is different only in that it didn't contain the timing element.
Here it is fully assembled:
And here it is in it's bits and pieces.
The color of the fluid in the ampule represented the time delay that would be effected when the ampule was crushed, running from a half hour to two hours, you can see what I mean with this picture of a complete timer kit.
The limpet was developed in Britain during WWII in a process that continues today in the form of the Rapid Equipping Force. The REF is an organization charged with taking good ideas from just about anyone, testing them, and if they work, get them to the troops in the field while bypassing the normal requisition channels.
The limpet mine was developed by a Mr. Stuart MacRae, the editor of a journal called "Armchair Science," along with a then-Captain C. V. Clarke, all based on a phone call from the War Office. The first of these mines were made using parts purchased from Woolworths - details here.
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