Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

146 drew attention to the fact1), that various testing laboratories had come to other results than the Berlin Testing Laboratory as regards testing the resistance to frost of sand-lime-bricks. On this occasion he expressed as his opinion, that presumably this was principally due to the different evaporation during the freezing. He further stated that at the Berlin Laboratory the freezing took place in a rather large room, the evaporation hereby possibly becoming somewhat greater than at other labora- tories ,where the freezing took place in a smaller case. G. added that presumably the tests of the Berlin Laboratory agreed more with the natural conditions, which always afforded ample op- portunity for evaporation. To this our Laboratory begs, how- ever, to remark that it is no easy matter to perceive which test with respect to evaporation is most accordant with the natural conditions. Indeed, the temperature of the bricks in nature is not 20° Centigrade but more probably something very near the freezing point, wherefore the evaporation becomes, of course, much less considerable than during any of the tests; but the bricks are, on the other hand, under natural conditions no doubt very rarely saturated or nearly saturated with water such as it is the case with bricks when being tested. That it is not only the test of resistance to frost of the Berlin Laboratory and the Danish States Testing Laboratory, which differ, appears clearly from some discussions in a sectional meeting held by the Franco-Belgian department of the Inter- national Association of Testing Materials on the 26. of January 1907. Here it was proposed to work at the next congress for a more precise composition of the conference regulations as to tests of resistance to frost, as it had been proved that even if the tests had been executed apparently in the same way at the va- rious testing laboratories i. e. according to the conference re- gulations, the results obtained often differed very much. During the proceedings Mr. Mercier reported that at Laboratoire des Ponts et Chaussées the bricks, whose resistance to frost was testeci, were only allowed to absorb 2/5 of the greatest amount of water, which it was possible for the bricks to receive in a certain manner, the bricks namely being placed in a reservoir, where a partial vacuum was produced; then water was admitted *) Tonindustrie-Zeitung 1908, p. 729.