peroxide of iron, sulphur, lime, asbestos, chalk, sulphate of zinc, and
carbonate of magnesia. When a sufficient thickness of this composition has
been applied, it is vulcanized under pressure at a temperature of 250° F.,
or a little higher. The material produced in this manner is said to have
the strength and durability of the best leather belts. Attempts have
recently been made to obtain a glue suitable for joining the ends of
driving belts, without the use of metal fastenings or sewing, and Messrs.
David Kirkaldy & Son have reported favorably on such a belt glue, which is
being introduced by Mr. W.V. Van Wyk, of 30 and 31 Newgate street, E.C. In
the test applied by them, a joint of this "Hercules glue," as it is called,
in a 4 in. single belt was stronger than the solid leather. When a tensile
stress of 2,174 lb., equivalent to 2,860 lb. per square inch of section,
was applied, the leather gave way, leaving the joint intact. Belts
fastened by a scarf joint with this glue are said to be of absolutely the
same thickness and pliability at the joint as in the main portion of the
belt, and thus insure freedom from noise and perfect steadiness. The
instructions for use are simple, and it requires only fifteen minutes for
the joint to set before being ready for use. From a rough chemical analysis
of the sample submitted to us, we find that it consists of gelatine, with
small amounts of mineral ingredients. Josef Horadam, some few years ago,
patented in Germany a process for preserving glues from decomposition, by
the addition of from 8 to 10 per cent. of magnesium or calcium chlorides.
The addition of these salts does not impair in any way the strength of the
glue, but prevents it from decomposing, and it may be that the "Hercules
glue" is preserved in a similar manner.

A cement of this nature, if thoroughly to be relied on, must be of great
value, although the great variation in the quality of leather, apart from
the difficulty hitherto experienced of securely connecting the ends
together, opens a wide field for a material of uniform composition, and