GUANO. 



237 



represented in the figure ; it consists of a flask capable 

 of containing about J pint, provided with a narrow 



Fig. 28. 



gas-delivery-tube bent twice at right angles. One 

 limb, rather the shorter of the two, is passed, air-tight, 

 through the cork of the flask, and bent upwards to 

 prevent, as far as possible, the escape of bubbles of gas. 

 This tube descends nearly to the bottom of the flask. 

 A second very narrow short tube is also passed through 

 the cork, and serves for the escape of air when the cork 

 is introduced. The longer limb of the delivery-tube 

 dips into a tall cylinder or tube, which is graduated 

 to cubic centimeters, or cubic inches. The flask is 

 half-filled with solution of chloride of lime ;* 1 grm. 

 of guano is then weighed in the small glass vessel (the 

 end of a test-tube) in which a few small shot have been 

 placed, in order that it may float upright. With the 

 aid of the handle of iron-wire shown in the figure, the 

 tube is let down so as to float upon the surface of the 

 solution of chloride of lime; the cork with the tube is 



* This solution must be carefully prepared and kept in a dark 

 place, in a closed vessel. It must contain an excess of hydrate of 

 lime, and therefore need not be perfectly clear. 



