By A. GANSWINDT.

"Water consists of one atom of oxygen and two atoms of hydrogen." This proposition will not be disputed in the least by the author; still, it may be profitable to indulge in a few stereo-chemic speculations as to the nature of the water molecule and to draw the inevitable conclusions.

From the time of the discovery, some 110 years ago, that water is a compound body, made up of oxygen and hydrogen, the notion prevailed up to within a quarter of a century that it was composed of even equivalents of the elements named, and all but the youngest students of chemistry well remember how its formula was written HO, the atomic weight of oxygen being expressed by 8, making the molecular weight of water (H = 1 + O = 8) 9. But the vapor density of water, referred to air, is 0.635, and this number multiplied by the constant 28.87, gives 18 as the molecular weight of water, or exactly twice that accepted by chemists. This discrepancy led to closer observations, and it was eventually found that in decomposing water, by whatever method (excepting only electrolysis), not more than the eighteenth part in hydrogen of the water decomposed was ever obtained, or, in other words, only just one-half the weight deducible from the formula HO = 9. The conclusion was irresistible that in a water molecule two atoms of hydrogen must be assumed, and, as a natural sequence, followed the doubling of the molecular weight of water to 18, represented by the modern formula HO.

Both the theory and the practice of substitution enable us to further prove the presence of two hydrogen atoms in a water molecule. Decomposing water by sodium, only one-half of the hydrogen contained is eliminated, the other half, together with all of the oxygen, uniting with the metal to form sodium hydroxide, HO + Na = H + NaHO. Doubling the amount of sodium does not alter the result, for decomposition according to the equation HO + 2Na = H + NaO never happens. Introducing the ethyl group into the water molecule and reacting under appropriate conditions with ethyl iodide upon water, the ethyl group displaces one atom of hydrogen, and, uniting with the hydroxyl residue, forms ethyl alcohol, thus: HO + CHI = CHOH + HI. Halogens do not act directly on water, hence we may not properly speak of halogen substitution products. By the action, however, of phosphorus haloids on water an analogous splitting of the water molecule is again observed, one-half of the hydrogen uniting with the halogen to form an acid, the hydroxyl residue then forming a phosphorus compound, thus: PCl + 3HO = 3HCl + P(OH).

Now these examples, which might readily be multiplied, prove not only the presence of two hydrogen atoms in the water molecule, but they further demonstrate that these two atoms differ from each other in respect to their form of combination and power of substitution. The two hydrogen atoms are certainly not of equal value, whence it follows that the accepted formula for water:

or as preferred by some: H-O-H, is not in conformity with established facts. Expressed as here shown, both hydrogen atoms are assigned equal values, when in fact only one of the atoms is united to oxygen in form of hydroxyl, while the second is loosely attached to the univalent hydroxyl group. Viewed in this light, water then is decomposed according to the equation: HO = H + (OH), never in this manner: HO = 2H + O. Hence, water must be considered as a combination of one hydrogen atom with one molecule of hydroxyl, expressed by the formula H(OH), and it is this atom of hydrogen not united to oxygen which is eliminated in the generation of oxygen or substituted by metals and alkyl groups. The hydrogen in the hydroxyl group cannot be substituted, excepting it be the entire group as such; this is proved by the action of the halogens, in their phosphorus compounds, upon water, when the halogen takes the place of the hydroxyl group, but never that of the hydrogen.

Now as to some logical deductions from the foregoing considerations. Hydrogen is by many looked upon as a true metal. This theory cannot be directly proved by the above, but it is certainly greatly strengthened thereby. To compare. Hydrogen is a powerful reducing agent; it is similarly affected by the halogens, the hydroxyl group, the acid radicals, oxygen and sulphur; hydrogen and members of the univalent alkali metals group are readily interchangeable; it forms superoxides analogous to the metals; its analogy to the alkali metals as exhibited in the following:

H H(OH) HCl HNO HSO HS HO
K K(OH) KCl KNO NaSO NaS KO

But if we consider hydrogen as a gasiform metal, we naturally arrive at the conclusion that water is the hydroxide of this gasiform metal, that is hydrogen hydroxide, while gaseous hydrochloric and hydrosulphuric acids would be looked upon as respectively the chloride and the sulphide of the metal hydrogen. This would then lead to curious conclusions concerning the hydroxyl group. This group would, by this theory, become an oxygenated metal radical similar to the hypothetical bismuthyl and uranyl, and yet one in which the metallic character has disappeared as completely as in the ferrocyanic group.

An entirely new light is shed by this view upon the composition of hydrogen peroxide, which would be looked at as two free hydroxyl groups joined together thus: (OH) - (OH), analogous to our di-ethyl, diphenyl, dicyanogen, etc. Considered as dihydroxyl, it would explain the instability of this compound.

The ethers proper would also be placed in a new light by this new conception of the constitution of the water molecule. The hydrogen in the hydroxyl group, as is known, may be substituted by an alkyl group. For instance, an alkyl may be substituted for the hydroxyl hydrogen in an alcohol molecule, when an ether results. According to the new theory this ether will no longer be considered as two alkyl groups connected by an oxygen atom, but as a compound built up on the type of water by the union of an alkyl group and an alkoxyl group. Thus ethylic ether would not be represented by

as heretofore, but by the formula CH(OCH), which is ethyl-ethoxol. Acetone would admit of a similar explanation.

Finally the assumption of dissimilarity in character of the hydrogen atoms in the water molecule possibly may lead to the discovery of a number of unlocked for isomerides.

Thus, by appropriate methods, it ought to become possible to introduce the alkyl groups solely into the hydroxyl group (instead of into the place of the loosely attached H-atom). In that case chemists might arrive at an isomeride of methyl alcohol of the formula H.(OCH), or at methoxyl hydride, a compound not alcoholic in character, or at a nitroxyl hydride, H(ONO), not of an acidic nature. Oxychlorides would be classed with this latter category, that is, they would be looked on as water in which the free hydrogen atom has been substituted by the metal, and the hydrogen atom of the hydroxyl by chlorine. This example, indeed, furnishes a most characteristic illustration of our theory. In the case just now assumed we arrive at the oxychloride; when, however, the metal and chlorine change places in the water molecule, the isomeric hypochlorous salts are the result. It is true that such cases of isomerism are as yet unknown, but we do know that certain metals, in our present state of knowledge, yield oxychlorides only, while others only form hypochlorous salts. This condition also explains why hypochlorites still possesses the bleaching power of chlorine, while the same is not true of oxychlorides.

However, it seems needless to multiply examples in further illustration of the theory.

Translated from the Pharmaceutische Centralhalle, by A.G. Vogeler. - Western Druggist.