Vitamin Q ?

I found these Sprague Vitamin Q caps while looking through a parts drawer:

Apparently they are still highly prized by our fellow travelers, musicians:

https://www.theartoftone.com/new-old-stock-sprague-vitamin-qs-more/

Exactly why this is I'm not sure. The "Vitamin Q" is apparently some proprietary oil used by Sprague to fill the cap (impregnant). They are paper caps, oil filled, metal bodied with glass ends and are considered hermetically sealed. Vitamin Q caps are supposed to be stable even at high/low temperatures and were prized for their longevity.

Incidentally hermeticity implies the use of metal, glass and/or ceramic as packaging materials. Plastics are NOT considered hermetic packaging materials. But due to the cost even the military uses commercial plastic devices in the 21st century. The idea with modern plastics used in packaging ICs is that even if moisture gets in it won't foul up the works.

I tried looking in several Allied and Lafayette catalogs from the 1950s and 1960s but no Vitamin Q caps were listed. Apparently they were intended for high-reliability applications for the military ?

I don't have any special test equipment for capacitors other than a cap meter. The smallest one I have

(although it doesn't say Vitamin Q on the package it appears to be one) is marked .0015 uF and reads 1.54 nF so still only 2.7% high, not bad after at least 55 years.

BTW, the fellow who gave me these capacitors along with a bunch of other electronic stuff from his basement worked in the aerospace industry so maybe that's where they came from ? I wish I had known they'd become valuable before soldering them into little toy electronic organs and other projects :)

OTOH, maybe he just got them from a surplus dealer: Poly Paks ad from February 1976 Poptronics: