抄録
The pH value of the several agar products has been estimated by means of glass electrode. (cf. Table 2, 3 and 4).
The results are as follows:
(1) The sulphuric acid ordinally used in the process of extraction is not recognized as free acid in the agar products, both naturally and artificially freezed and thawed.
(2) The decomposition of the agar sol by the simple heating, (cf. Table 1), effecting on the strength of jelly, and the coloration by the warming of the agar products are remarkably affected by the pH value of the products estimated by solution; if the pH value is lower, these changes are more remarkable.
(3) The causes of the phenomena (2) are presumably based on the essential properties of the agar products.
