520. Packing.

521.
522.
(a) Some sawdust should be placed to a depth of half an inch in it.
(b) The hydrometer stem should then be gently placed in the case (not pushed down through the sawdust to the foot of the tin).
(c) It should then be thoroughly packed round with sawdust (not rammed too tightly) allowing equal distances all round between the bulb and the case.
(d) Then the case should be filled up to the top with sawdust. This should allow a layer of at least half an inch above the top of the stem.
(e) Then the cap should be put on without undue force and securely fastened.