Double glass walls and needle: what they have in common

1. Step 1. Double glass walls — is part of — Dewar flask. Two bulbs, one inside the other.
2. Step 2. Dewar flask — evolved into — Vacuum flask. A household Dewar flask.
3. Step 3. Vacuum flask — has part — Mirror. The silvering reflects heat radiation.
4. Step 4. Mirror — is made of — Silver. A silver coating.
5. Step 5. Silver — is material for — Syringe. Early needles were silver.
6. Step 6. Syringe — has part — Needle. A hollow needle.

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