A cheap and powerful freezing mixture may be made by pulverizing Glauber's salts finely, and placing it level at the bottom of a glass vessel. Equal parts of sal ammoniac and nitre are then to be finely powdered, and mixed together, and subsequently added to the Glauber's salts, stirring the powders well together; after which adding water sufficient to dissolve the salts, a degree of cold will be produced, frequently below Zero of Fahrenheit. But Mr. Walker states, that nitrate of ammonia, phosphate of soda, and diluted nitric acid, will on the instant produce a reduction of temperature amounting to 80 degrees. It is desirable to reduce the temperature of the substances previously, if convenient, by placing the vessels in water, with nitre powder thrown in occasionally. _Microscopic Examination of the Blood_. By the aid of Tulley's achromatic microscope, and under highly magnifying powers, it has recently been discovered that the globules of the blood congeal into flat circular bodies, and arrange themselves in rows, one body being placed partly underneath another, and in like manner as a pile of similar coins, when thrown gently down, would be found to arrange themselves. This curious effect has been attributed to the vitality yet remaining in the blood, during the act of congealing. At any rate it is a most singular fact, for although we might naturally conceive that the flattened circular plates would place themselves in juxtaposition, yet we never could have supposed that they would have partly slipped underneath each other. In order to make this very curious experiment, it is necessary that the blood, as freshly drawn, be slightly and thinly smeared over the surface of a slip of crown, or window glass, and be covered with a very thin slip of Bohemian plate glass; and thus some slight inequalities in the thickness of the layer of blood between them will be produced, and which are necessary to succeed in producing the very curious appearances abovementioned.--_Gilt's Repository_. _To make the Liqueur Curaçoa_.