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is an important item in an efficient and economical factory. Weight for weight, the proportion of fuel to pottery burnt in a kiln is from 25 to 70 per cent., according to the nature of the ware. And a kiln requires fuel of certain value, chiefly with regard to high volatile matter and calorific power. A fuel of low volatile content does not furnish a flame sufficiently long to penetrate through all the kiln, and much of the ware is accordingly under-fired. But with the best intentions, there is probably no process of manufacture which wastes so much fuel as pottery burning. The contents of the kiln are often so valuable representing hundreds, and perhaps thousands of pounds that it is false economy to risk deterioration of ware from first to second quality in order to reduce the fuel bill. The chemist must therefore steer a middle course between undue pro- digality and economy in fuel. Much is to be hoped of gas- fired regenerative kilns, but these are still a long way from superseding the older type of potters' kiln. A continuous kiln might only burn 5| tons of fuel to the 10 in an up- draught and the 6| of a down-draught kiln, and there is a saving in sagger loss of 50 to 80 per cent., but the wear and tear of a continuous kiln, especially where the gas impinges on the brickwork, is enormous. The most prominent gas-fired kilns for ceramic purposes are the Hoffman, Buehrer, Mendheim, Ehrenwerth, Venier, Stein- mann, Lehse, and Czerny-Deidesheimer. For details the reader should refer to special works on the subject ; but