How to Test Eggs. The following method of determining the age of eggs is practised in the markets of Paris:—About 6 oz. of common cooking salt is put into a large glass, which is then filled with water. When the salt is in solution, an egg is dropped into the glass. If the egg is only one day old it immediately sinks to the bottom; if any older, it does not reach the bottom of the glass. If three day old, it sinks only just below the surface. From five days upwards it floats; the older it is, the more it protrudes out of the water. To make Lemon Curd. Half a pound of butter, melted ; 1lb of castor sugar, three lemon rinds, juice of two, six eggs, leave out two of the yolks. Put all into a pan, and stir until it thickens.