between the sections with a layer of felting cloth or other
compressible material, thus forming expansion joints. Sometimes he
slightly roughens the surface of the material, to give better foothold to
pedestrians. Sometimes the grooving is made in imitation of ordinary
granite paving sets. In tramway pavement there are grooves to give a grip
to the horses' feet, and a slight camber between the rails. He states
that a great advantage in laying a pavement by the method is that, when
any repairs are necessary, a piece of the exact size can be manufactured
at the works, and stamped to the same pattern as the adjoining pavement,
then placed at once in position on the removal of the worn portion, thus
saving the time necessary for the setting of the concrete on the
spot.--_The Engineer_.

* * * * *

A NEW BLEACHING PROCESS.

In the spring of 1883 a Mr. J.B. Thompson, of New Cross, London, patented
a new process of bleaching, the main feature of which consisted in the
use of carbonic acid gas in a closed vessel to decompose the chloride of
lime. The "chemicking" and "souring" operations he performed at one and
the same time. The reactions which took place in his bleaching keir were
stated by the inventor as follows:

Cl.\
1. Ca ) + CO_{2} = CaCO_{3} + Cl_{2}.
OCl./

2. OH_{2} + Cl_{2} = (ClH)_{2} + O.

3. CaCO_{3} + (ClH)_{2} = CaCl_{2} + CO_{2} + H_{2}O.

That is, in 1 chloride of lime and carbonic acid react upon each other,
producing chalk and nascent chlorine; in 2 the nascent chlorine reacts
upon the water of the solution and decomposes it, producing hydrochloric
acid and nascent oxygen, which bleaches; in 3 the hydrochloric acid just
formed reacts upon chalk formed in 1, and produces calcium chloride and
one equivalent of water, and at the same time frees the carbonic acid to
be used again in the process of decomposing the chloride of lime.

When the process was first brought to the notice of the Lancashire
bleachers, it met with an amount of opposition. Some bleaching chemists
declared the process was not patentable, as fully half a century ago
carbonic acid was known to decompose chloride of lime. The patentee's
answer was emphatic, that carbonic acid gas had never been applied in
bleaching before. After some delay one of the largest English cotton
bleachers, Messrs. Ainsworth, Son & Co., Halliwell, Bolton, threw open
their works for a fair test of the Tho