684 
CONVERSAZIONE. 
Mr. Hamilton Pendred, C.E., of the Wire Tramway Company, exhibited a 
working model of the wire tramway. This tramway is intended for the 
transport of mineral and agricultural produce in localities as yet unprovided 
with railways. It consists of an endless wire rope, supported on a series of 
pulleys carried by substantial posts, and set in motion by a steam-engine, 
through the medium of a Fowler’s clip-drum. The stone or other material is 
conveyed in boxes attached to the rope by a pendant of peculiar shape, which 
maintains the load in equilibrium, and at the same time enables it to pass the 
supporting pulleys with ease. The system may briefly be defined as a develop¬ 
ment of a plan not unusual in some mining districts of bridging over a river 
or ravine by a single wire-rope, by which, carried in a bucket suspended 
by a pulley, the necessary loads are transmitted from one point to another. 
The principal advantage of this system is its economy. No bridges, tunnels, 
or embankments are required ; in fact its cost does not very greatly exceed 
that of the erection of a system of telegraph wires. 
A most ingenious self-regulating apparatus for making nitrous oxide gas 
was exhibited in operation by Mr. Porter. The apparatus is peculiar in 
being provided with what is termed a thermal moderator. This instrument 
is practically a small cistern in communication with the lower part of the first of 
the series of wash-bottles, and containing a float. The wash-bottle and the 
cistern being in communication, the water which is used for washing the gas 
stands at the same height in both as long as a similar pressure is exerted 
upon its surface in each vessel, but as soon as gas begins to be evolved from 
the fused nitrate of ammonia in the generating flask, the w r ater in the wash- 
bottle is subjected to increased pressure ; a portion of it is forced into the 
cistern, and the float is raised to a corresponding extent. Now if we imagine 
the float to be in connection with a lever attached to the cock which regulates 
the supply of gas to the burner under the generating flask, we shall have no 
difficulty in understanding the modus operandi of this simple arrangement. 
As an additional safeguard against accidents, the first wash-bottle is so fitted 
up that, in the event of the delivery-tube becoming blocked, the water is 
ejected from the bottle, and free egress provided for the gas, which, in rush¬ 
ing out, sounds a whistle. This apparatus, which appeared to work with 
great regularity, supplies a want that has been felt since the introduction of 
nitrous oxide as an agent for producing anaesthesia in dentistry. 
Another novelty was shown by Dr. Estor in the shape of his process for 
the preservation of meat. This plan consists in hanging the meat in a close 
chamber or safe, and subjecting it to the action of sulphurous acid and 
chlorine gas applied in succession, and generated by the burning of a small 
pastille. The safe exhibited contained a joint of meat from an animal stated 
to have been slaughtered more than a month ago. Dr. Estor’s explanation 
of the theory of the process is this :— 
“ When the pastille is burning, sulphurous acid is produced, of which a 
considerable portion is absorbed by the meat. As the bowl becomes hot, 
chlorine gas is given off* from the interior. These gases separately have the 
power of decomposing water slowly, but in conjunction with each other their 
action in this respect is very rapid, the sulphurous acid taking the oxygen 
and the chlorine combining with the hydrogen. Thus the original gases 
disappear, and two new substances are formed, namely, sulphuric acid and 
hydrochloric acid. The two powerful gases having done their work are 
transformed into two others which are harmless and, it may be said, whole¬ 
some. Sulphurous acid alone will preserve meat for a time; so will also 
chlorine, but the meat thus preserved is nauseous ; whereas when the gases 
are used conjointly in the manner above described and in due proportions no 
trace of either remains.” 
