NATIONAL PHYSICAL LABORATORY. 
cooling curves of metals. In these furnaces the specimen can be 
heated or cooled at any convenient rate by regulating its speed of 
travel through the furnace, the temperatures at various parts of the 
furnace being steady, but varying from point to point. 
Researches on light alloys have been carried out, the tests lasting 
over some years. The behaviour of these alloys under different con- 
ditions of temperature, heat treatment, or mechanical treatment has 
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CHEMISTRY 
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GROUND PLAN OF THE NATIONAL PHYSICAL LABORATORY. 
been investigated, and in this connexion most valuable information 
has been obtained from the use of the experimental rolling mill. 
Other sections devoted to the chemistry of aeronautical materials and to 
general chemical analysis must be passed over with a mention. _ 
Another section is devoted to research on optical glass. Not only is 
it sought to arrive at the correct composition of glasses of various 
optical properties, but the problems of actual manufacture on a large 
211 
