Baths in Chemistry, a contrivance for subjecting different substances either to a steady heat, not liable to sudden fluctuations, or to a temperature which shall never exceed the boiling point of water. In the first case, the vessel containing the substance to be heated is imbedded in a vessel containing sand, or other slow conductor of caloric, and set in a furnace, and this is called a sand bath; but if it is desired that the temperature shall not exceed 212°, water is substitute for sand, and this is called a water-bath. A familiar example of a water-bath is the common glue-pot, which consists simply of a vessel containing water, in which is immersed another vessel containing the glue. Mr. Vazie recently patented culinary vessels on the same principle, an illustration of which is subjoined; a being the external vessel containing water; b the internal vessel containing the food; and c the cover. The principle of this method of limiting the temperature has received a more extensive application, by Messrs.

Beale and Porter, who have obtained a patent for employing, as a heating medium, various substances, which rise in vapour at different degrees of the thermometric scale, some exceeding, and others falling, below the boiling point of water, such as alcohol, ether, naphtha, turpentine, and various essential oils. Under the head Boiler will be found a description of an apparatus upon this principle.