34 



THE ART OF PROJECTING. 



get in, wipe it carefully out. When the varnish is 

 dry, and the pieces are firmly fixed together, putty up 

 the bottom of this hole so that it will hold water. 

 When this is dry, it can be used to hold fluids of most 

 kinds, but it is especially fitted for water containing ani- 

 malcules, or vinegar with eels. It should be put back 

 of the focus of the condenser, for the great heat there 

 will boil the water in a little while, and the temperature 

 of no more than 130° Fah. will quickly kill most all 

 kinds of infusoria. Suitable water for examination can 

 be found in old rain barrels, stagnant pools, water in 

 which flowers have been standing for a day or two, an 

 infusion of hay in water, and will be found very interest- 

 ing. The larva of the mosquito is a lively and amus- 

 ing thing when magnified to five or six feet in length. 



THE CHEMICAL TANK. 



For chemical experiments, and a variety of others, 

 a tank of larger proportions will be necessary. The 

 accompanying diagram (Fig. 20), shows the construc- 

 tion. Provide two pieces of clear, white glass, of the 

 same size, about five inches by six, for the sides. These 

 may be kept apart by a strip of rubber, about one-half 



of an inch thick, 

 bent and cut at 

 the corners, the 

 whole clamped 

 together by three 

 or four clamps, 

 as shown. If rub- 

 ber with flat sides 

 is not easily pro- 

 curable, a piece 

 of rubber t u b - 

 Fig. 20. ing will answer 



