High-dried malt. I've been trying to get clear in my mind exactly what is was. Partly because those flipping Truman's Burton logs are full of the stuff. The text below makes it sound like something half-way between pale and amber malt. Though the way its use is described, it strikes me as perhaps being more like Mild Ale malt with maybe a touch more colour.
This most important operation is divided into two stages, drying and curing. During the curing the character of the product is finally determined. The drying is effected by passing large volumes of warm air through the layer of malt. A high temperature is avoided at first, otherwise the diastase would be crippled or destroyed, and the starch gelatinised. During the drying process the malt is frequently forked and turned over, so that a free passage of air may be ensured.
On the first day of kilning, the temperature does not exceed 95° to 100° F. During the second day this is slowly raised to 120° to 125°, the third day to 140° to 150°, the fourth day the malt is finished off at the desired temperature. This is allowed to fall gradually, and the malt is heaped up on the kiln. The time during which a malt is kept on the kiln varies according to the quantity; some maltsters dry and cure in forty-eight hours, but the majority take three or four days. The object in view is gradually to raise the temperature to a maximum, and maintain it for a length of time sufficient to enable the heat to penetrate to the centre of the individual corns. During the curing process the diastatic capacity is greatly restricted, the malt is rendered friable, and the flavour is developed.
Varieties of malt:—
Pale malt for pale ale brewing is finished off at a temperature of . . 180°-200° F.
High dried malt for mild ale and stouts 200°-225° F.
Amber malt for mild ale and stouts 225°-240° F.
Brown malt is dried off rapidly over a wood fire. It has a much higher colour than amber malt, and no diastatic capacity. Black or patent malt is malt which is roasted, so as to produce the maximum amount of colouring matter. Roasted barley is now largely used in place of black malt, as it is cheaper and in most cases gives equally satisfactory results.
In this country malt is cured by exposure to the products of combustion from the kiln furnace. Curing by indirect heat, viz. the products of combustion being excluded from actual contact with the malt, is not usual in the United Kingdom, but is practised more in Continental and American maltings. Probably the part played by the products of combustion in conferring flavour on the malt has been much exaggerated. Excellent beers have been obtained from malts cured by indirect heat."
Source: "The brewing industry" by Julian L. Baker, 1905, pages 27 - 28.
I haven't forgotten Southby. More to come from him. On malt and brewing water.