treatment precipitates a number of impurities, including multivalent anions such as sulfate, phosphate, citrate and oxalate, which precipitate as their calcium salts and large organic molecules such as proteins, saponins and pectins, which aggregate in the presence of multivalent cations. In addition, the alkaline conditions convert the simple sugars, glucose and fructose, along with the amino acid glutamine, to chemically stable carboxylic acids. Left untreated, these sugars and amines would eventually frustrate crystallization of the sucrose. Carbonatation In the carbonation step carbon dioxide is bubbled through the alkaline sugar solution, precipitating the lime as calcium carbonate (chalk). The chalk particles entrap some impurities and absorb others. A recycling process builds up the size of chalk particles and a natural flocculation occurs where the heavy particles settle out in tanks (clarifiers). A final addition of more carbon dioxide precipitates more calcium from solution; this is filtered off, leaving a cleaner, golden light-brown sugar solution called "thin juice". In 1935, the inputs required to process of beets to sugar was outlined as follows: limestone coke (to convert limestone to quicklime) water Phosphatation Phosphatation is achieved by adding phosphoric acid after adding calcium hydroxide to form calcium phosphate. The remaining sugar is then dissolved to make a sugar liquor (about 70 percent by weight solids), which is clarified by the addition of phosphoric acid and calcium hydroxide that combine to precipitate calcium phosphate. The calcium phosphate particles entrap some impurities and absorb others, and then float to the top of the tank, where they are skimmed off. Decolorization After any remaining solids are filtered out, the clarified sugar liquor is decolorized by filtration through the use of bone char, which is made from the bones of cattle, a bed of activated carbon or, in more modern plants, ion-exchange resin. Evaporation The thin juice is concentrated by multiple-effect evaporation to make a "thick juice", roughly 60% sucrose by weight and similar in appearance to maple syrup. It is also sterilised with UV light. Thick juice can be stored in tanks for later processing, reducing the load on the crystallization plant. Crystallization Feeding the thick juice to the crystallizers is the first step of this subprocess. Recycled sugar is dissolved into the juice and the resulting syrup is called mother liquor. The liquor is concentrated further by boiling under a vacuum in large vessels (the so-called vacuum pans) and seeded with fine sugar crystals. These