A new development was made in 1880 by Clamond. He prepared a paste by grinding up calcined and powdered magnesia with a concentrated solution of magnesium acetate; by forcing this through a press he obtained a ribbon which was then wound crosswise on a wooden shaper, dried carefully, and ignited. In his later experiments twenty per cent. of zirconia was added to the magnesia. The mantle was supported in a platinum cage and heated in the flame of a mixture of coal-gas and heated air. This mantle gave an intense light, but was too fragile for extended use. In the following year, Lundgren patented a process by which lime, magnesia, and zirconia, made into a paste by the addition of gum, were forced through a press, and the resulting thread wound on a graphite-covered shaper. The mantle so obtained was stable, and gave an intense white light, but after having been heated for some time the oxides crumbled to powder. A modification of this process was introduced by Knöfler in 1894, in an attempt to use a cellulose solution containing rare earth salts; this was forced through jets, and the cellulose precipitated as a continuous thread from which the mantle was made. A further modification of Knöfler’s process by Plaisetty in 1901 was technically successful; but these developments must be taken up in a later chapter (_vide_ p. 307). In 1883 a process was patented by Fahnehjelm in Stockholm, by which for the first time a cheap and stable mantle of considerable efficiency was produced, and which, but for the advent of the Auer mantle, would undoubtedly have been commercially successful. Fahnehjelm’s mantle consisted of an arrangement of needles or lamellæ of magnesia, lime, zirconia, etc., suspended over a burner. The plates and needles were usually arranged in the form of a comb of suitable shape, and were found to give an intense light, and to be long-lived. In later forms the combs were made of rods of magnesia dipped into solutions of chromium salts. The great disadvantage of this invention lay in the fact that the combs required to be heated in the flame of water-gas, in order to secure a good incandescence; had it been possible to attain a sufficiently high temperature by the use of coal-gas, it is doubtful whether the Auer mantle would have ever been evolved.