The rates of hydrolysis of sodium pyrophosphate and triphosphate in solution have been measured a t 65.S0C. over the pH range 2.0 to 12.0 and the phosphorus concentration range 0.10 to 0.25 atomic weights per liter. The reactions were found to be first order providing a constant concentration of hydrogen ion was maintained in the reaction flask. Both reactions are acid catalyzed but only the hydrolysis of triphosphate was found to be base catalyzed. Pyrophosphate and triphosphate apparently hydrolyze independently of each other.

1383containing 17% alcohol were extracted for 2 minutes with 20 ml. of isoamyl acetate and the absorbances of the extracts measured P.P.M. Si02 P.P.LM. As P.P.M. SiOn P.P.M. -49 a t 323 mp against an isoamyl acetate blank, Beer's law was

Filter‐paper chromatographic methods have been developed which permit the separation and de‐ termination of condensed phosphate anions containing up to four phosphorus atoms per ring and of linear structures containing from one to nine phosphorus atoms per chain. These methods have been used to study the anions produced when soluble sodium phosphate glasses of a range of compositions and methods of preparation are dissolved in water. The analyses are in qualitative agreement with the structure of phosphate glasses proposed by Van Wazer. X‐ray and other evidence is presented which indicates, for the range of compositions studied, that the structures of condensed phosphate anions found in solution correspond to similar structures of condensed phosphates in the glass before dissolution and do not arise during the solution process. The study thus supports the polymer approach to the constitution of glasses for the range of com‐ position studied.

The general rate equations for the hydrolysis of pyrophosphate anion proposed by Muus have been proved to be inapplicable over the pH range 2.0 to 11.0. A general rate equation is proposed which is based on the assuhlption that each anionic species of pyrophosphoric acid hydrolyzes a t a rate which depends on its concentration, and that the only role of the hydrogen ion concentration is to determine the proportion of each species present in the solutio~l. A mechanism for the hydrolysis of pyrophosphate anion is suggested.The dissociation constants of pyrophosphoric acid have been determined a t 65.5"C. for the concentration range 0.08 to 0.18 molar.

A simple colorimetric procedure was developed for apparent color determinations utilizing platinum‐cobalt standards and expressing the results in Hazen units. The method entails measuring the absorbance of a sample with a colorimeter using two broad band filters; a second absorbance reading is required to obtain a suitable correction for particulates. With this method, the human response factor is minimized, and the precision, as estimated by standard deviation, is one Hazen unit.