1690. Metallic Freezing Mixture

1690. Metallic Freezing Mixture.

An interesting experiment may be made by-melting together 59 parts tin, 1031/2 lead, and 183 bismuth. If this be finely rasped or powdered, and introduced into 108 parts, by weight, of quicksilver, a thermometer immersed in the mixture will sink to nearly 3° Fahr.; and water placed in a thin test-tube, and allowed to remain for a few minutes in this bath, will be completely frozen.

1691. How to Keep Ice in Summer

1691. How to Keep Ice in Summer. No refrigerator or ice-box will prevent, or even retard the melting of the ice, which does not combine the following conditions: It must have double sides, bottom, and lid, with the space between the two casings filled with some non-conducting substance, in order to exclude the external temperature; and the inner lid or cover should be practically, if not hermetically, air-tight, in furtherance of the same result. If external air enters, it will bring its own temperature with it. There should be also a drainage-pipe at the bottom to carry off, instantaneously, every drop of water formed by the melting of the ice, and this pipe should either be fitted with a trap or curved in such a manner as to prevent the cold air from escaping. It is even more indispensable to carry off every drop of the water than it is to exclude the air - a view not generally entertained by consumers of the article, but which, according to experiments made, seems to be fully demonstrated. Thus, on exposing a piece of ice weighing, say 25 pounds, to the air, at a temperature of 75°, but so placed that it is perfectly drained, it will be found to have scarcely disappeared at the end of 24 hours. Wrap the same piece in 3 or 4 thicknesses of blanket or flannel, and place it in a small tub exposed to the same temperature, and as the water filters through the blanket, the ice will stand in its own water, and will be all dissolved in 5 or 6 hours. Wrap the same piece of ice carefully in a blanket, and place it on a grating, or on four crossed sticks, so that no water can accumulate underneath, and at the end of 3 or even 4 days it will not have entirely melted.