The following are instructions on making a small chemical tank for magic lantern experiments. Procure three glass plates 3 1/4 in. by 4 1/4 in. From one of these plates a half-circle must be cut out with a diamond, using a half-circle of wood as a guide. Canada balsam is used as the eminent. It must be placed in a saucer and baked in the oven until it is quite hard when cold. The three pieces of glass should now be heated in the oven or on an iron plate placed over a burner until they are too hot to be touched by the hand. The melted Canada balsam must now be spread with a smooth stick on both sides of the glass plate from which the hal:-circle has been cut, the other plates being pressed ore on each side of it to remove all air bubbles. The whole should then be placed under a weight till cold. The tank thus made will appear like Fig. 1, and may be placed in an ordinary carrier. With a lantern suitable for experiments requiring a wider tank two 4 1/2-in. by 4i-in. plates may be used, cementing them together as described above by three pieces of plate glass, the bottom piece 4 1/4 in. by rin. and the two side pieces each 3 1/2 in. by 3/4 in. to form a rectangular tank 3 1/2 in. by 2 3/4in. by about |in. deep (see Fig. 2). These measurements may be altered if necessary to suit the lantern.

Fig. I.

Fig. 2. Chemical Tank for Magic Lantern.