opening for the receiver to pass through. This process is carried on with success in the works at Niagara.
Another type of furnace worthy of attention is that devised by Memmo (17). The space in which the fusion takes place consists of a prismatic iron receiver, A, covered inside with plates of carbon, and closed at the bottom by a plate of graphite, B, resting on an iron plate; the bottom can be raised or lowered by means of a toothed-wheel arrangement. Two electrodes, CG (with a three-phase current three electrodes are used), are so placed in the walls of the iron receiver A that an arc light is formed between them immediately above the plate B, The charge is put into a chimney arrangement, -D, above Ay and is lowered into the receiver as required by a scoop-shaped feeder. In the patli of the arc some carbide is formed, and this flows over the graphite plate and gradually solidifies as j5 is lowered. A fresh charge is then introduced, and in this way there is an almost continuous production of carbide between the electrodes CG. A solid column of carbide is formed, the upper level of which is kept at a constant height. When the bottom plate B has been lowered to a certain depth, the top part of the column is supported by a plate intro- duced from the side, and the lower portion is then cut out. When this lower portion has been removed, the plate B is pushed up, the side support withdrawn, and the process continued.
The carbon monoxide which is evolved, and the air which is heated by the hot carbide, are each led up through a tube into 2>, and thus the charge is preliminarily heated before being introduced into the furnace. The same gases may also be used for heating the space Ay in which the fusion takes place.
Silent Electrical Discharges. — If the conductor of a Holtz electrical machine be connected to a point, the electricity flows out through this, and a so-called electrical wind is formed.
In a dark room a small ball of light can be seen at the
X
�� �
