Note 136 — A CYCLOPÆDIA OF PRACTICAL RECEIPTS, &c. VOLUME II (continued 29)

Prof. Pfaundler has shown that an acid containing 66·19 per cent. of H2SO4, is the most advantageous to employ for this purpose; one part of an acid of this strength with 1·097 parts of snow forming a refrigerating mixture which will reduce the temperature to -37° C. (-36° F.). For practical purposes it is suggested an excess of snow would be better, since the refrigerating value of the mixture is thereby largely increased, though the lowest temperature is not obtained. See Ice.