Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

3) We now presume the brick thus masoned in that the side B is front side, further that the surface of the wall where the brick is placed faces south-west. Let us imagine that for some days it has been a storm from the south-west and rain. The shell situated between A and B has then become saturated with water by and by, the stripe A preventing the water from penetrating further into the brick. If now it becomes dry weather again for some days with a temperature above the freezing-point the greater part of the water will evaporate and the brick not be damaged. But on the weather changing suddenly to some degrees of frost while the brick is dripping wet, an ice-shell will form outside the brick preventing further evaporation of the water in the shell between A and B. All the water in this shell will freeze in consequence of which the shell is easily blown off or its coherence with the other part of the brick so much weakened, at any rate, that a repetition of the named treatment conveys a disruption of the shell. Something very like may for the rest take place when such a brick is standing in a pile in nature. Let us imagine, for instance, that the same brick is standing uppermost in a pile of bricks the stretcher-side B turned up- wards and other bricks on the sides of it. Through a longer period it has been raining or perhaps snowing with ensuing thaw. The shell between A and B has become saturated with water. The spaces between the brick and its neighbouring bricks are filled with amnions or melting thawy snow. The weather suddenly changes to frost, and the shell between A and B is loosened. At fig. 22, p. 63 is given a transverse section of an exceedingly heterogeneous brick, partly frozen to pieces, and derived from one of the piles on the building place of Christiansborg. It is distinctly seen how the disruptions, due to the frost, follow the structure in the brick. As mentioned above there may, of course, be many various forms of heterogeneity not necessarily alone due to deficient working of the clay, but also to other reasons. A deficient bur- ning may, for instance, produce »over-fired«' bricks i. e. such where the surface is much harder burnt than the heart of the brick. Also this sort of heterogeneity will be able to occasion the destruction of the brick when acted upon by the frost. From that which has been put forth here and perhaps will