ALDEGRETER, or ALDEGRAF, IIEmnicit, 1502-62 ; a German painter and engraver. From his style, which closely resembles his master's, he has been called the "Albert Darer of Westphalia." His engravings put him in the first rank of "little mas ters." Specimens of his paintings are very rare.
ALDEHYDE is a volatile fluid produced by the oxidation and destructive distillation of alcohol and other organic compounds. Its discoverer, Dbbereiner, called it light oxygen ether; its present term is an abbreviation of alcohol dehydrogenitum, its composition being represented by that of alcohol from which two atoms of hydrogen have been abstracted. In the article on this subject in Watts's Dictionary of Chemistry, ten different modes of obtaining this substance are given. It is sufficient here to state that the best modes of preparing it may be found in that work, or any recent treatise on organic chemistry. It is a thin, transparent, colorless liquid, very inflammable, burning with a blue flame, and having a spec. gr. of 0.8, a boiling-point of about 71°, and a
pungent, suffocating odor. It mixes in all proportions with water, alcohol, and ether, and dissolves sulphur, phosphorus, and iodine. As is shown in the article ALcouoLS„it constitutes an intermediate stage in the oxidation of alcohol into acetic acid. A. must be regarded as a monobasic acid, inasmuch as it contains one atom of hydrogen replace able by a metal. Thus, when potassium is gently heated with A., one atom of II is replaced by one of K, the resulting compound being aldehydate of potash, Various salts of this kind may be formed, of which the most important is aldehydate of ammonia, or aldehyde-ammonia, C,H,(Ai which is obtained in transparent shining crystals, and is a compound that has led chemists to the discovery of a large number of very remarkable derivatives.