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Acids and Alkalies

naoh, hc1 and light

ACIDS AND ALKALIES.

The effect of acids (HC1) and alkalies (NaOH) can be seen by adding 1 c.c. of the acid (or alkali) of a definite concentration to 1 c.c. of a glowing mixture of photogenin and photophelein. The concentration of the acid or alkali in the mixture will thus be one-half of the concen tration added. The results are given in table 6.

The effect of acid (HC1) and alkali (NaOH) was also studied in the following way: 1 c.c. fairly dilute (1 Cypridina to 10 c.c.) photophelein was mixed with 1 c.c. n/500 HC1, allowed to stand 1 hour and then neutralized by adding an equal volume of n/1000 NaOH and tested for light by adding photogenin. The photophelein was therefore in contact with n/1000 HC1 for 1 hour. In this way the effect of acid on photogenin and photophelein can be separated. The results are given in table 7.

Even very small concentrations of NaOH added to a glowing mixture of photogenin and photophelein will decrease greatly the amount of light (table 6). Thus if we add 1 c.c. n/500 NaOH to 1 c.c. of a brightly glowing mixture, making the concentration of NaOH n/1000, the light instantly becomes very dim and remains so for a considerable time. If NaOH be added to a concentration of n/250, the light disappears com pletely; if we now neutralize the NaOH with n/250 HC1, the light returns, faint.

Still smaller concentrations of HC1 prevent light-production. Thus (table 6) n/2000 HC1 extinguishes the light from a luminous mixture, but on neutralization with n/2000 NaOH, the light returns and is fairly bright. The effect of NaOH and HC1 is therefore to inhibit light-production, and not to immediately destroy the photogenin and photophelein (tables 6 and 7). The reversibility is not apparent if the acid or alkali are only slightly stronger than the values given. (Note also from table 7 that the photogenin is more readily affected by HCl and especially by NaOH than the photophelein.) In the case of acid and alkali, as with so many other substances on the light-giving material, the effect is to an extent reversible if the substance is removed. The concentration of HCl which inhibits light production is the same as that affecting cells, although the concentra tion of NaOH necessary to inhibit light-production is somewhat greater than that necessary to affect cells (12 and 13).