Abstract
According to a report on the production of pure isomorphous hydroxyfluorapatite (HFA) by acidimetric precipitation from a watery soln., a descr. of expts. on the indication of the solubility of the HFA was given. It was found that the solubility of the HFA is considerably diminished even by a small F content The probability that HFA may originate in the enamel by the influence of drinking water containing F, and that the enamel should thus become less soluble and therefore be more resistant to dental caries is discussed.