Whilst the glyoxal is oxidized easily by very diluted nitric acid, it requires an excess of strong acid to convert the glycolic into oxalic acid. Frequently when I employed less nitric acid in the oxidation of alcohol, as mentioned in my first paper on this subject, I obtained along with glyoxal a liquid which possessed many properties in common with glycerine, C3 H8 03. As it is most likely to contain, like glyoxal, glycolic and glyoxylic acids, two atoms of carbon, I suppose it to be homologous with glycerine. Its composition would be represented by the formula Č2 H6 O3. If the latter is compared with that of glyoxal, it becomes at once apparent that both stand in the same relation to each other as alcohol and common aldehyde, and that æthyle-glycerine, glyoxal, and glyoxylic acid, stand to each other as alcohol, aldehyde, and acetic acid. Therefore the oxidation of the alcohol by nitric acid appears not to extend at once to the production of glyoxal and glyoxylic acid, but the alcohol simply absorbs oxygen, and is converted into another alcohol homologous with glycerine. The æthyle-glycerine would unite with more than one atom of a monobasic acid, and accordingly we find its aldehyde-the glyoxal-combining with two atoms of bisulphite of ammonia, and its acid—the glyoxylic acid-bibasic or perhaps tribasic. Wurtz has recently produced a new alcohol which he calls glycol. This alcohol would stand between æthyle-glycerine and common alcohol (C2 H6 O), and it is not improbable that it is produced by the first action of nitric acid on common alcohol. If so, the oxidation of the latter would proceed thus :— Glycolic acid would stand in the same relation to glycol, C2 HO2, as glyoxylic acid to æthyle-glycerine, or acetic acid to common alcohol: Glycerine, C3 H8 O3, should be produced from propylic alcohol as æthyle-glycerine is formed from common alcohol; and the glycerine should yield with nitric acid an aldehyde, C3 H6 O3, and an acid, C3 H6 O4, homologous with glyoxal and glyoxylic acid. The results of my experiments on this point and on the other substances formed by the action of nitric acid on common alcohol, C2 H6 O, will be communicated in a future Number of this Magazine. Tartaric, citric, and malic acids, which occur frequently in nature, accompany each other so often, that from this fact alone one would suppose some similarity in their constitution. I have shown on another occasion, that if glyoxylic and tartaric acids are regarded as bibasic, their radicals are polymeric. Thus— C4 H4 04.0 Tartaric acid, C2 H2O2.0 Glyoxylic H H.O acid, H H.O or C2H2O2, added to the formula of glyoxylic acid, would give that of tartaric acid,— Other connexions have also been pointed out between these two acids. The same difference in composition shows itself between glycolic, malic, and citric acids : Or if we adopt for the radical C2 H2O2 the symbol (Gly), we get, (Gly) HHO = Glycolic acid, (Gly) HHO = Malic acid, (Gly)3 HHO = Citric acid, in the same way as carboxyle, oxalyle, &c. enter the type water, Glycolic acid which contains (Gly) is monobasic, malic acid with (Gly) is bibasic, and citric acid containing (Gly)3 is tribasic. The decompositions of glycolic, malic, and citric acids agree Iwith the above view. On application of heat the following changes take place : (Gly)3 HHO-HHO=(Gly)3 = C6H606 It is interesting to notice that these acids, on the loss of HHO, do not diminish in their basicity; aconitic acid is still tribasic, maleic acid bibasic; and although it is not established by experiment, it is highly probable that glycolid is still monobasic. The conversion of maleic acid into carbonic acid and lactid has not yet been realized, nevertheless it follows from the experiments of Engelhardt that lactid is intimately connected with these acids. On distilling lactic acid, he obtained citraconic acid; but the latter is homologous with maleic acid, from which, according to the above equation, the lactid ought to be formed. The chief character of the decompositions of these acids is to part with water and carbonic acid. This peculiarity is explained if it is assumed that they originate from the radical (Gly) =C2 H2O2, or substances polymeric with it, combining with water, or oxygen and water. According to Berthelot, from carbonic oxide and water formic acid is produced. The latter contains formyle, CHO, which is easily oxidized to water and carbonic acid. The radical C2 H2O2 is polymeric with formyle. The products of decomposition of malic, citric, and tartaric acids, whether by fermentation or by caustic potash at a higher temperature, are either oxalic or acetic acids, or substances belonging to the same series of compounds, viz. acetone and propylic acid. The radical C2 H2O2 is closely connected with oxalic and acetic acids. If we add oxygen, it is converted into oxalic acid, as in the case of glycolic and glyoxylic acid; and on addition of hydrogen, we get a substance containing the elements of acetic acid:· C2 H2O2+02=C2 H2O4 oxalic acid, C2 H2 02+H2=C2 H1 O2 acetic acid. Queenwood College, Dec. 15th, 1856. Phil. Mag. S. 4. Vol. 13. No. 83. Jan. 1857. E IN VI. On Mesolite and Faröelite (Mesole). By Dr. HEDDLE*. a late Number of the Magazine I submitted analyses of natrolite, so named from the large quantity of soda it contains; its formula is NaO, SiO3+Al2Ò3, SiÓ3+2HO. The mineral which stands next to this in the system is scolezite, the formula of which is CaO, SiO3+Al2O3, SiO3+3HO; differing from natrolite in containing lime instead of soda, and in having an additional atom of water. It is thus rational to presume that the most common impurity in either of these substances would consist of a greater or less amount of the bases which constitute their specific distinction; that natrolites would be found containing some lime, and that scolezites would occasionally be contaminated with soda. Published analyses show that this is the case; and I have lately pointed out, that, in the case of "galactite," the occurrence of an impurity of this nature had for years given a distinct name to what is merely an instance of chemical replacement. So long as this substitution of one substance or element for another occurs in varying proportion, or in such as cannot be expressed by a rational formula, the substance in question is to be considered as merely a chemically impure (I use chemically here to distinguish from mechanically impure) specimen of that mineral which in composition it most resembles; when, however, the replacement occurs in definite proportions, then a distinct mineral is before us, with as good claims to be considered a species as either of the originals, the result of whose combination we may theoretically consider it. Thus, in my five analyses of galactite, we had the lime of scolezite occurring in the soda mineral in the per-centage proportions of 16, 82, 93, 2.63, 4.312, no one of which proportions† agrees with * Communicated by the Author. + Except, perhaps, the last; the specimen was from Glen-farg. The analysis stated in full was,— Silica Alumina Lime Soda Water 47.84 27.112 4.312 10.304 10.24 99.808 These proportions point to the formula (2NaO, CaO) 3SiO3+3(Al2 O3, SiO3)+7HO, which gives 6 = 346386 = 47.41 1= 35000 = 4.79 But the above formula may be written 2(NaO, SiO+Al2O3, SiO3+2HO)+(CaO, SiO3+Al2O3, SiO3+3HO) 2 atoms natrolite + 1 atom scolezite the very reverse, in fact, of mesolite. This compound may be called Fargite. |