_Freezing-Points of Calcium Chloride Solutions._ _________________________________________________________ | | | | | Percentage of | Specific Gravity. | Freezing-point. | | CaCl_2. | | | |_______________|___________________|_____________________| | | | | | | | | Degs. C. | Degs. F. | | 6 | 1.05 | -3.0 | +26.6 | | 8 | 1.067 | 4.3 | 24.3 | | 10 | 1.985 | 5.9 | 21.4 | | 12 | 1.103 | 7.7 | 18.1 | | 14 | 1.121 | 9.8 | 14.4 | | 16 | 1.140 | 12.2 | 10.0 | | 18 | 1.159 | 15.2 | 4.6 | | 20 | 1.170 | 18.6 | -1.5 | |_______________|___________________|__________|__________| Calcium chloride will probably be procured in the solid state, but it can be purchased as a concentrated solution, being sold under the name of "calcidum" [Footnote: This proprietary German article is a liquid which begins to solidify at -42° C. (-43.6° F.), and is completely solid at -56° C. (-69)° F.). Diluted with one-third its volume of water, it freezes between -20° and -28° C. (-4° and-l8.4° F.). The makers recommend that it should be mixed with an equal volume of water. Another material known as "Gefrierschutzflüssigkeit" and made by the Flörsheim chemical works, freezes at -35° C. (-3° F.). Diluted with one-quarter its volume of water, it solidifies at -18° C. (-0.4° F.); with equal parts of water it freezes at -12° C. (10.4° F.). A third product, called "calcidum oxychlorid," has been found by Caro and Saulmann to be an impure 35 per cent. solution of calcium chloride. Not one of these is suitable for addition to the water used in the generating chamber of an acetylene apparatus, the reasons for this having already been mentioned.] for the protection of gasholder seals. Glycerin itself resembles a strong solution of calcium chloride in being a viscid, oily-looking liquid; and both are so much heavier than water that they will not mix with further quantities unless they are thoroughly agitated therewith. Either may be poured through water, or have water floated upon it, without any appreciable admixture taking place; and therefore in first adding them to the seal great care must be taken that they are uniformly distributed throughout the liquid. If the whole contents of the seal cannot conveniently be run into an open vessel in which the mixing can be performed, the sealing water must be drawn off a little at a time and a corresponding quantity of the protective reagent added to it. Care must be taken also that motives of economy do not lead to excessive dilution of the reagent; the seal must be competent to remain liquid under the