The views of Becher on the composition of substances mark little essential advance on those of the two preceding centuries, and the three elements or principles of salt, mercury and sulphur reappear as the vitrifiable, the mercurial and the combustible earths.
Mixed with air, like every other combustible gas, acetylene forms an explosive mixture.
- These compounds possess properties very similar to those of ammonia, the lowest members of the series being combustible gases readily soluble in water.
The furnace has, in addition to the usual tuyeres near the bottom, a second set near the throat in order to effect a complete oxidation of all combustible matter.
After having previously roasted the tube and copper oxide, and reduced the copper spiral a, the weighed calcium chloride tube and potash bulbs are put in position, the boat containing the substance is inserted (in the case of a difficultly combustible substance it is desirable to mix it with cupric oxide or lead chromate), the copper spiral (d) replaced, and the air and oxygen supply connected up. The apparatus is then tested for leaks.