Analytical Chemistry. 281 
the level of the proper amount of liquid, e.g. 200 c.c. The same amount 
of coloring matter being thus always diffused in the same volume of the 
contents of one flask, in which the neutralization has been satisfactorily 
effected, may be kept as a standard of color for the succeeding trials, as 
the tint remains constant for hours, being unaffected by the absorption 
of carbonie acid. The greatest convenience and accuracy of measure- 
ment are attained by using burettes provided with Erdmann’s swimmer 
the wide mouthed flasks and Jet flow from the burette a slight excess, e. g. 
50¢.¢., of standard acid. The solution of the carbonate of soda is fa- 
: p 
allowed to become perfectly cold, then add ten drops of cochineal and 
lastly the standard alkali to neutralization, diluting to the proper volume. 
oo. illustrate the accuracy of the process and the calculations employed, 
'e following actual data may be useful. The normal acid was made b 
Sine 5U ¢. c. of oil-of-vitriol to the volume of ten liters and had half 
€ strength above recommended. ‘The alkali was from a stock on hand 
and more dilute than necessary. : 
Relation of acid to alkali. 
Exp. I, 20 c.c. SO, == 82°8 c.c. KO, or 1: 1°64 
Exp. II, 20 c.c. SO, = 32°8 e.c. KO, or 1: 1°64 
Exp. II, 40 ¢.c. SO, = 65°7 c. c. KO, or 1: 16425 
We have accordingly : , 
lec. SO, = 1°64 cc. KO and 1 c.c. KO = 0°60976 c.c. SO,. 
Absolute strength of acid and alkali, 
Exp. 1. 0-4177 grm. of carbonate of soda were treated with 44-2 ¢.¢, 
of 80,. To neutralize the excess of the acid were required 3:8 . e. KO, 
Which correspond to 2°32 e.c. SO, (3°8X0°60976). Deducting this 
from the total amount of acid (44°2—2-32) we have 41°88 c.¢. of acid, 
*quivalent to the carbonate of soda taken. 
41°88 c.c. solution of SO, = 0-4197 grm. NaO CO,. 
pbkP- TL. 0-4126 grm. NaO Cog treated with 44 c.c. SO, required 
ae & e. KO. 428060976 = 2°61¢.c.S8O,. 44 — 2°61 = 41°39 
c 
8° 
41°39 c. c. solution of SO, = 0°4126 grms, NaO CO,. 
It is convenient to calculate how much acid corresponds to 53 deci- 
Stammes of carbonate of soda, since the relation of any other substance 
‘0 the acid is then obtained by substituting its equivalent number for 53 
(the equivalent of NaO CO,), thus: 
