854 Mechanics, Physics, and Chemistry.

tal is run off; G, a roller frame, upon which the bed of the furnace re- volves; It, a bevel pinion gearing into the teeth of the wheel for giving motion to the revolving bed; x,. a lower frame furnished mith wheels,

by means of which the revolving bed, after being lowered by the screw L, may be withdrawn from beneath the arched cover for repairs or other-

wise. The wheels of the lower frame run upon rails, R ; ~ is a sand-joint for preventing the access of cold air into tile furnace between the fixed top and the revolving bed ; ~ is the flue leading to the chimney. The arrangement of the furnace above described is the best with which the inventor is at present acquainted for carrying his invention into effect, but he does not limit him- self to the details thereof, as they may be variously modified.

By keeping the metal stirred about for some timo whilst in its molten condition, by means of the rotating furnace, the sulphur and other impurities contained in it are allowed to readily fly off, so that the apparatus answers, in some measure, the purpose of a puddling furnace, and leaves the metal itself in a semi- puddled state, somewhat approaching the condition of wrought iron, but still with sufficient fluidity to allow of its being run imo moulds and used for many purposes for which wrought iron is at present employed.

The axis of the improved furnace is placed by preference about 10 ° out of tile perpendicular.

$

On tJ~e Melting and Solidification of Water. M. Mousson reports in the .Bibliotheque Universelle de Gen~ve, an

interesting set of exlSeriments made by him for the purpose of deter- mining the effect of pressure on the melting point of ice.

He first exposed a number of capillary tubes of diameters varying from 0"0074 inch to 0"1 inch, and containing columns of water about 12 inches long, to the air. The exposure lasted seven days, during which

Gutta-percha as an Insulating #Lqterial. 355

the temperature never rose above 28"5 °Fah. , and went down every night below 23 ° Fah. Upon withdrawing the tubes, all those whose diameter was greater than 0'36 inch had frozen; and all those whose diameter was less than 0"275 inch had remained liquid, nor did a sud- den blow cause them to freeze. By arranging the tubes in an inclined position so as to plunge them in a vessel of water, it was found that the formation of the ice externally, favored theTr freezing. The two tubes of least diameter (0"013 and 0"0074 inch) alone remained liquid.

The sheet of water between two plates of glass pressed together by screws, will not fl'eeze; but if they be simply laid on each other, the sheet which is then thicker, will freeze.

:Blocks of ice from 3 to 4"5 inches cube were placed in a hydraulic press and reduced to sheets of a few hundredths of an inch in thick- hess. Although the temperature of the air was only a .few degrees above the freezing point, the water trickled from the blocks on all sides.

In order to prevent the expansion of the water during freezing, a quantity was introduced into a cylindrical cavity of about 0"24 inch in diameter, in a heavy-prism of wl:ought iron. The water in the cavity was compressed by a powerful screw, and then exposed to cold. The water remained liquid at 26"6 ° ]~'ah. In an attempt to reduce the tem- perature to 23 ° Yah., the apparatus began to leak.

A quantity of water was/then introduced into a cavity in a similar prism of steel, and after being frozen, the ice was compressed by means of a powerful screw moving a copper cone. The apparatus was sur- rounded by a freezing mixture, the temperature of which varied from --0"4 ° to --6.7 °Fah. ; the temperature of the air was below 3"2 °, and the movement of the screw was performed so slowly as to make-but two tm'ns, (or forward motion) of 0"36 inch in four hours. The ice was liquified by the pressure, as was imlieated by the position of a small wire index which had been frozen into the mass.

The pressure to which it had been exposed was 13,070 atmospheres~ by which the freezing point was reduced below 0 ° ]?ah.

Can a suitable ~sula t lng MaterlaZ be found Possessing a Zower Sflee~fie Induetive Capacity than Gutta-percha?* By E. O. WILD- I~IAN WtIITEttOUSE, ~ S q .

The amount of induction and consequent retardation in submarine wires--other conditions being alike--would seem to depend so greatly upon this property of the insulating sheath, that it would be most de- sirable that some experiments should be made with the object of deter- mining this point.

A substance, or rather solution or compound, suggested by Mr. Statham, and recently perfected and adopted at the gutta-percha works --with which the wire is coated, before it receives the gutta-percha-- will be found~ if I mistake not~ to be a step in this direction, while at the same time it enhances largely the perfection of the insulation. •

I t still might be an object o f legitimate research to discover some • From the London:Mechanics' Magazin% October~ 185~,