clay, silica, or other translucent white pigments to the C.P. green in the tank before filtration or the press cakes of C.P. green may be mixed with these translucent pigments in edge roll mills or otherwise. By varying the proportions of chrome yellow and Prussian blue many beautiful tones of green are obtained. The chromates of strontium, barium, and zinc are used as pigments to a limited extent.
A LECTURE EXPERIMENT TO ILLUSTRATE OSMOTIC PRESSURE Recalling a very simple and impressive experiment from college days the writer has found that the phenomenon of osmotic pressure may be simply and convincingly demonstrated as follows: A large carrot, beet, winter radish, turnip, or similar root is bored out by means of a one inch auger bit. The cavity thus formed is filled with a heavy table sirup or molasses and a stopper with glass tube attached is placed in position as shown in the accompanying sketch. The stopper should be well sealed with paraffin and wired in. The osmotic pressure cell thus made is immersed in a beaker of water. The osmotic pressure will cause the liquid to rise in the tube to a height of eight feet or more.
Museum Identifies China by Chemical Tests. Collectors of old china will he interested to know that the authenticity of certain types of old porcelain can now be determined b y chemical tests. Under the direction of Dr. Alexander Scott tests have been worked out in the laboratory of the British Museum t h a t have helped classify several doubtful pieces in the Museum collections without disfiguring the specimens. Old patent acts were consulted t o determine the chemical composition of Old Bow and Chelsea china while tests were then resorted to, t o detect the presence of various phosphate components known t o have been used in its composition.-Science Senwe
