260 



TABLES FOR REFERENCE. 



Comparison of Weights. 



Avoirdupois. Apothec. Metric. 



i grain = .0648 gram, 



i dram -4558 dr. = 1.7718 " 



2.194 dr. i dram 3.888 " 



I ounce -9115 oz. = 28.3495 " 



1.0971 oz. i ounce 31-1035 " 



I lb. 1.215 Ib. = 453-59 



.822910. i lb. = 373.242 " 



.5643 dr. = 15.432 gr. i gram. 



Comparison of Thermometer Scales. 

 / C. = \(t - 32) F. / F. = f /' C. -f 32. 



Specific Gravity and Percentage Composition of 

 Solutions. 



The following tables are based on Baumfs hydrometers? 

 a set (two) of which is assumed to be available. 



The scale of the hydrometer for liquids lighter than water 

 has its zero-point at the bottom. This is the point to which 

 the instrument sinks in a 10$ solution of common salt. The 

 10 point is that to which it sinks in pure water. One de- 

 gree of the scale at any part is one tenth of this interval. 



The hydrometer for liquids heavier than water has its zero 

 point at the top of the scale. This is the point to which it 

 sinks in pure water ; and the 10 point is that to which it 



