Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

145 Further the chief-engineer of the Clay-Laboratory, Mr. Fischer- Möller, went to Berlin according to the demand of the same fac- tory to be acquainted with the method followed at the test of resistance to frost here. It became clear to him that the prin- cipal difference between the Berlin test and that of the Laboratory was implied in the evaporation from the surface of the bricks being much greater in Berlin than h e r e. The supposition for real tests of resistance to frost is that the pores of the material that has to be examined are quite or practically quite filled with water. On the freezing of the water its volume is augmented, and then, for one thing, it is dependent on the strength of the brick but principally on the quality of the pores how capable the material is to resist the bursting ac- tion consequent to the expansion of the water. When a brick with a temperature of about 20° Centigrade is taken into a room with a temperature of 15° Centigrade below zero, a great evapo- ration of water will take place from the surface of the brick, and the water left in the brick must then be thought to disperse through the whole volume of the brick. Thus the la tier is sa- turated with water do more and it may even be thought that so much water evaporates that, on the frost finally setting in, the contents of water are so slight that on the whole no bursting action takes place. The easier the evaporation from the surface of the brick takes place, the less rigorous are therefore the test of resistance to frost. In Berlin the bricks are clasped into straps so that free evaporation can take place from the whole surface. At our La- boratory the method followed at the tests of resistance to frost has always been to place the bricks on the stret- cher-sides, partly on the bottom of the freezing-case, partly above one another. Some arbitrariness may be thought to come in here on s o m e of the bricks happening to lie some- what often er than others on [he bottom of the case, but for common bricks the Laboratory had never found any real oc- casion for scruples in this respect. At the General Meeting of the German Union of Sand-Lime- Brick Factories in February 1908 the director of one of the departments of the Berlin Testing Laboratory, Professor Gary,