Calcium Ultraphosphates

These compounds might perhaps be regarded as dehydrated acid metaphosphates. Kroll isolated them when studying the constitution of basic slag, and gave to them the following formulae: - CaO.3, CaO.3P₂O₅.2H₂O, 2CaO.3P₂O₅, and a basic compound, 5CaO.3P₂O₅, the general formula for the acids from which they are derived being nH₂O.3P₂O₅.