48 JUNIOR GRADE SCIENCE 



the bottle is found. If now the bottle is emptied and carefully dried 

 inside and out, and filled with the liquid of which the density is 

 required, say spirit? of wine, and weighed again, we have the weight 

 of the liquid which just fills the bottle, or the weight of equal volumes 

 of the liquid and water. The ratio weight of liquid divided by 

 weight of water gives the relative density of the liquid. 



21 TO FIND THE DENSITY OF A SMALL QUANTITY 

 OF A LIQUID. 



i. Use of U-tube. For the determination of the density of a liquid, of 

 which only a small quantity is available, a tube of the form shown in 

 Fig. 38 can be used. 



Fia. 38 A tube with fine bore FIG. 39. Method of filling a density 

 near ends, for the determination tube having a fine bore, 



of the densities of liquids. 



The tube is filled with liquid by putting one of the open ends in a vessel 

 containing the liquid, and attaching to the other end a pipette, by means 

 of which suction can be applied (Fig. 39). When the tube is full the pipette 

 is taken off, and the tube is then ready to be suspended from the balance. 

 This method of finding density will be used later. 



Determination of relative density with small U-tube. When 

 only a small quantity of a liquid is available, a smaller vessel must be 



