COLTS′FOOT. This popular herb is the Tussilago farfara of Linnæus. It is a demulcent bitter, and is slightly stomachic and tonic. It is much esteemed by the lower classes in coughs, shortness of breath, and other affections of the chest. The leaves form the basis of most of the British herb tobaccos, and have been recommended to be smoked in asthma and difficulty of breathing.—Dose. One or two wine-glassfuls of the tea or decoction (1 oz. to the pint) ad libitum.
COLUM′BIC ACID. See Tantalic Acid.
COLUM′BIUM. See Tantalum.
COMA. A deep, heavy sleep, from which the patient cannot be aroused. See Apoplexy.
COMACHROME FOR DYEING THE HAIR BLACK. Nitrate of silver solution, with pyrogallic acid. (Reveil).
COMBINA′TION. In chemistry, the union of dissimilar substances. The great general laws which regulate all chemical combinations admit of being laid down in a manner at once simple and concise. The laws of COMBINATION BY WEIGHT are as follows:
“1. All chemical compounds are definite in their nature, the ratio of their elements being constant.
“2. When any body is capable of uniting with a second in several proportions, these proportions bear a simple relation to each other.
“3. If a body, A, unite with other bodies, B, C, D, the quantities of B, C, D, which unite with A, represent the relations in which they unite among themselves, in the event of union taking place.
“4. The combining quantity of a compound is the sum of the combining quantities of its components.” (Fownes.)