| Description | /1 1911 /2 1921 /3 1931 - also including details from pearl dust, "refined" bicarbonate and "sesqui" carbonate plants. Recording results of tests and analyses of samples of materials used and produced. With fortnightly, monthly and annual averages. "Reference page" at front of each volume explains method of analysis adopted. Surviving volumes are a sample only, taken from census years. |