READING TEST BOTTLES. 



303 



made in using bottle shown in Fig. IV is twice as 

 great as the same error made when using bottle 

 shown in Fig. II. An error made in using bottle 

 shown in Fig. Ill is II/2 times as great as the 

 same error made in using bottle shown in Fig. IV. 



-5.% 



IQ% 



F1G.IV. 



These errors used for illustration may be due to 

 either over or under reading, caused by an over- 

 sight, slipping of the dividers, or any foreign sub- 

 stance which may have found its way unnoticed 

 into the fat column. 



The meniscus in Fig. IV occupies about .8 per cent 

 on the reading and in extreme cases 1 per cent. In- 

 cluding the curvature at the bottom, the reading 

 between the extreme ends of the fat column, a-b, is 

 .8 per cent to 1 per cent too high. For practical 

 purposes, read from a to b and subtract nearly 1 per 

 cent. This will come nearer to the right reading than 



