Further studies on the metachromatic reaction of metaphosphate

Polymetaphosphates of molecular weights 690 and 1090 give a weak metachromatic reaction. Metaphosphates with molecular weights in the range 3600–20,600 react strongly metachromatic. But since equal weights of different high-molecular compounds give practically the same metachromatic intensity, it is not possible to distinguish between the various polymers on the basis of metachromasy.Storage for 24 hr. at room temperature of aqueous solution of high-molecular metaphosphate leads to significant diminution in molecular weight, but the metachromatic reaction remains unaltered. There is no liberation of orthophosphate.Subjecting aqueous solutions of high-molecular metaphosphates to ultrasonic vibrations does not bring about significant changes in the metachromatic reaction.The decrease in the absorption of toluidine blue at 630 mμ on the addition of metaphosphate does not always correspond with the increase in absorption at 530 mμ.