Crenic acid

Quell-reife, /. sufficient steeping, -salz, n. spring salt, well salt. -satzsSure, /. apocrenic acid, -saure, /. crenic acid, -schicht, /. swelling layer, -sole, /. spring brine, well brine, -stock, m. steep tank, steeping cistern. -substanz,/. substance that swells. 

Crenic acid and Apocrenic acid, the components soluble in water... 

Humic acid, CkTUCU (or C0II30FUlmic acid, C10H3oOi5 Crenic acid, C10H21O16 Apocrenic acid, C21H12Oi2... 

Research on the chemical properties of humic substances was extended by the Swedish investigator Berzelius (1839). One of his main contributions was the isolation of two light-yellow-colored humic substances from mineral waters and a slimy mud rich in iron oxides. They were obtained from the mud by extraction with base (KOH), which was then treated with acetic acid containing copper acetate. A brown precipitate was obtained ctilled copper apocrenate. When the extract was neutralized, another precipitate was obtained, called copper crenate. The free acids, apocrenic and crenic acids, were then brought into solution by decomposition of the copper complexes with alkali. These newly described humic substances were examined in considerable detail, including isolation, elementary composition, and properties of their metal complexes (Al, Fe, Cu, Pb, Mn, etc). 

Fulvic acid Soluble in alkali, not precipitated by acid Crenic acid, apocrenic acid Glucic acid, apocrenic acid Fulvic acid ... 

It has been known since the earliest studies that humic substances formed insoluble salts with a wide range of metal ions. Many di-, tri-, or tetravalent ions will bring about the precipitation of a greater or lesser amount of humic substances from solution. An early example of this was the use of copper to precipitate apocrenic acid and crenic acid (Berzelius, 1839). In modern times the technique has been used with some success by Dubach et al. (1961) and Sowden and Deuel (1961). 

The deposit was extracted with caustic potash solution and excess of acetic acid and copper acetate solution added dark brown copper apocrenate was precipitated. Ammonium carbonate then precipitated light green copper crenate from the filtrate. By decomposing the copper salts in water by hydrogen sulphide solutions of the acids were formed. These on evaporation in vacuum left amorphous yellow crenic acid and dark brown apocrenic acid. 

Mulder investigated humic and ulmic acids and humus substance, and determined the amounts of apocrenic, crenic, and humic acids in fertile soil. He gave the formulae crenic acid apocrenic acid ulmic... 

Waksman (1936) recommended abandonment of the whole nomenclature of humic acids, beginning with humins and ulmins, through the whole series of humus, hymatomelanic, crenic, apocrenic, and numerous other acids, and ending with the fulvic acid and humal acids . Notwithstanding, terms such as humic acid, humin, fulvic acids, and others have survived and will undoubtedly continue to be used in the future. Most studies on humus chemistry involve preliminary separations on the basis of solubility characteristics, and abandonment of these terms would cause even greater confusion than their continued use. For example, reference to the alkali-soluble, acid-insoluble material as humic acid is considerably less cumbersome than repeated reference to the alkali-soluble, acid-insoluble fraction. ... 

Berzelius (1833) appears to have pioneered a serious study of OM in natural waters. He discovered the dissolved organic compounds with acidic properties in the mineral spring Porla (Sweden). These compounds were called crenic and apocrenic acids. Berzelius assumed that their salts were washed out from soil humus intact . Oden (1919) found the common term for these acids — fulvic acids (fulvus = yellow). Aschan (1932) attributed them to the water humus group, being typical for peat, river and lake waters. 

Three different compounds make up HSs Humin (defined as insoluble), humic acid (HA, insoluble at a pH of 1) and fulvic acid (FA, soluble at any pH). Other names used to describe HS are ulmic, h5rmatomelanic, gray humic, brown humic, crenic, apocrenic or 5fellow acid (Swift (1985)),... 

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