What is nitrate of calcium, a substance having a grayish white color, occuring in efforescences on old walls, and in limestone caves, especially where there exists decaying animal matter called?

nitrocalcite — Nitrate of calcium, a substance having a grayish white color, occuring in efforescences on old walls, and in limestone caves, especially where there exists decaying animal matter. (Webster's 1913.)

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