Nucleic acid is at present of unknown constitution; decomposition products are: phosphoric acid, uracil or 2.6-dioxy-pyrimidin,1 cytosin or 2-oxy-6-amino-pyrimidin, thymin (nucleosin) or 2.6-dioxy-5-methyl pyrimidin hypoxanthin 1 or 6-oxypurin, xanthin or 2.6-dioxypurin, adenine or 6 amino-purin, guanine or 2amino-6-oxypurin, pentoses (l-xylose), laevulinic acid, ammonia, etc. The nucleic acids vary with the source of the proteids, there being considerable differences in chemical composition.
The first term includes simple sugars containing two to nine atoms of carbon, which are known severally as bioses, trioses, tetroses, pentoses, hexoses, &c.; whilst those of the second group have the formula C12H22011 and are characterized by yielding two monosaccharose molecules on hydrolysis.
We may notice that the pentoses differ from other sugars by yielding furfurol when boiled with hydrochloric acid.
To settle this point it is necessary to consider the configuration of the isomeric pentoses - arabinose and xylosefrom which they may be prepared.
If the asymmetric system adjoining the COH group, which is that introduced in synthesizing the hexose from the pentose, be eliminated, the formulae at disposal for the two pentoses are CH 2 (OH) - - - COH CH 2 (OH)+-- COH.