---+-----------------+--------+--------------------------------- | | | {Alkali} No.| Description of |Reaction|c.c. N/10 { or } Required for | Liquor | | { Acid } Neutralization ---+-----------------+--------+--------------------------------- 1 |{New puer }| Acid | 7·4 alkali |{before goods }| | | | | 2 |{The same after }|Alkaline| 0·57 acid |{goods }| | | | | 3 |{New puer }| Acid | 8·1 alkali |{before goods }| | | | | 4 |{The same after }|Alkaline| 3·25 acid |{goods }| | | | | 5 |{Used puer after}|Alkaline| 5·00 acid |{goods }| | | | | 6 |Spent puer |Alkaline| 6·6 acid ---+-----------------+--------+--------------------------------- Determinations made in this way are more accurate than the colorimetric method above described. Puer liquors after use are found by the electrometric method generally on the alkaline side, whereas such liquors show neutral to phenolphthalein owing to some action of the bate constituents on the indicator. PUER LIQUORS IN ELECTROMETRIC APPARATUS. ---+--------+---------+-------+---------+------------------------- | | c.c. of | | c.c. of | | P.D. |N/10 KOH | P.D. |N/10 HCl | | Before |required After |required | No.| Skins | for | Skins | for | Description of Liquor | | 50 c.c. | | 50 c.c. | | volt |liquor to| volt |liquor to| | |0·69 volt| |0·69 volt| ---+--------+---------+-------+---------+------------------------- A1 | 0·622 | 1·95 | .. | .. | New puer A2 | .. | .. | 0·747 | 1·9 | A1 after 2 packs skins B1 | ·607 | 3·7 | .. | .. | New puer B2 | .. | .. | ·770 | 3·1 | B1 after 3 packs skins C1 | ·580 | 4·3 | .. | .. | New puer C2 | .. | .. | ·762 | 2·8 | C1 after 2 packs skins D1 | ·580 | 5·2 | .. | .. | New puer D2 | .. | 0·8 | ·680 | .. |{D1 after 1 pack skins | | | | |{(still on the acid side | | | | |{ of 0·69) E1 | ·570 | 6·2 | .. | .. | D2 + 4 buckets more puer E2 | .. | .. | ·720 | 0·8 | E1 after 1 pack skins F1 | ·610 | 3·0 | .. | .. | New puer F2 | .. | 0·5 | ·680 | .. |{F1 after 1 pack skins | | | | |{(still on the acid side | | | | |{of 0·69) ---+--------+---------+-------+---------+-------------------------