Om Materialprøvningens Udvikling i Norden
Og om Statsprøveanstaltens Virksomhed

■ * ' _______________ I" ‘ - '"S '■’>**_____________ '____________________________ 178 took fire, but to fix the latter moment is not easy. We shall not here enter more particularly upon these tests of which nothing is hitherto published, but an account will be rendered for tests of resistance to fire made with impregnated and unimpregnated wood and executed for Akts. Dansk Imprægneringskompagni at Copen- hagen; the further details of these occur in the Annual Report of the Laboratory for 1908. The experiments tended to find out how long it took to burn through some wood-flakes joined by slit and tongue of a size of some square metres. The rule followed during the experiments was this. In an ex- perimental house, built for the same purpose, and of which fig. 321) at page 89 shows both a vertical section a—b, and the ex- perimental house seen from above, were placed the said wood- flakes in a sloping position, as it appears from the vertical sec- tion, so that the flame from 3 gas-burners lying below could lick up along the flakes. During the experiment the temperatures could be measured by means of Le Chatelier’s electric pyrometer, the latter being placed across the two nearest burners through the lower observation-hole. It was noted, both when the flake had been burnt through and whether the wood, on the gas having been turned down, went on burning or became extinct by itself. Altogether 8 experiments were made. The main result was: 5 impregnated flakes were burnt through in respectively 18, 20, 20, 46 and 50 minutes, while 3 unimpregnated were burnt through in 4 and 14 minutes. The gas having been turned down the wood-flakes of the unimpregnated wood went on burning without becoming extinct, but among the 5 impregnated wood-flakes Ihis was not the case for 3 wood-flakes for more than at most a few minutes, and for two only in a few places and presumably espe- cially because being boards of Pitch Pine where these were very resinous. The photographs above show an impregnated flake alongside with an unimpregnated one after being worked upon by the fire through a quarter of an hour, respectively at p. 90 in fig. 33 On the figure: »Observationshul« means peep-hole, »Aftræk« means outlet and »Gasbrænder« means gas-burner. »Snit a—b« means section on a—b.