SODA.— Alkalimetry.
and aluminate; but all these together are classifiedas “available soda,” and properly so, as for most pur-poses they are just as good as sodium carbonate.The test is expressed professedly in percentages ofsodium oxide (Na 2 0), and accordingly chemicallypure sodium carbonate ought to test = 58-49, or,say, 58| degrees. It is, however, not usual in thiscountry to certify the strength of soda ash accordingto its real equivalent of 23 for Na, or 106 forNagCOg; but according to an assumed equivalent of24 for Na, or 108 for Na 2 CO s , called the “old”equivalent. The figures in Pattinson’s table (givenbelow), called “English degrees,” are calculated onthis basis, according to which pure sodium carbonatetests 59-26 per cent. The tests made in Newcastle,London, and Glasgow agree with this; but the“Liverpool” test, which does not seem to followcertain rules, shows about 1 per cent more. Another
831
source of error is frequently imported by not filter-ing the solution of soda ash before testing it. Thecalcium carbonate and ferric oxide thus count equallywith the available soda, and makes it appear *a halfper cent, and often more than that, too high; thiscustom is, however, not an acknowledged one, andcertainly seems very reprehensible. In Germany soda ash is sold by its percentage of sodium car-bonate (all “available soda” being calculated assuch), and in France by Decroizilles’ degrees. Thelatter are supposed to show how much sulphuric mono-hydrate (II 2 S0 4 , equivalent 98) corresponds to thepercentage of Na 2 C0 3 (equivalent 106); pure sodiumcarbonate accordingly tests 92-45° Decroizilles.The following table, composed by John Pattinson,will be found very useful for a comparison of thedifferent degrees used by English , German, andFrench chemists, with the real percentages of soda:—
ALKALIMETRICAL TABLE.
Percentageof Soda.
Carbonateof Soda.
Degrees.
Decroizilles’
Degrees.
Percentageof Soda.
Carbonateof Soda.
Degrees.
Decroizilles*
Degrees.
Percentageof Soda.
Carbonateof Soda.
Degrees.
Decroizilles*
Degrees.
30-0
51-29
30-39
47-42
46-0
78-66
46-60
72-71
62 0
106-01
62-82
98-00
30-5
52-14
30-90
48-21
46-5
79-51
47-11
73-50
62-5
106-86
63-32
98-79
31 0
53-00
31-41
49-00
47-0
80-37
47-62
74-29
63-0
107-72
63-83
99-58
31-5
53*85
31-91
49-79
47-5
81-22
48-12
75-08
63-5
108-57
64-33
100-37
32-0
54-71
32-42
50-58
48-0
82-07
48-63
75-87
64*0
109-43
64-84
101-16
32-5
55-56
32-92
51-37
48-5
82-93
49-14
76-66
64-5
110-28
65-35
101-95
33-0
56-42
33-43
52-16
49-0
83-78
49-64
77-45
650
111-14
65-85
102-74
33-5
57-27
33-94
52-95
49-5
84-64
50-15
78*24
65-5
111-99
66-36
103-53
34-0
58-13
34-44
53-74
5o-0
85-48
50-66
79*03
66-0
112-85
66-87
104-32
34-5
58-98
34-95
54-53
50-5
86-34
51-16
79-82
66-5
113-70
67-37
105-11
35-0
59-84
35-46
55-32
51-0
87-19
51-67
80-61
67-0
114-56
67-88
105-90
35-5
60-69
35-96
56-11
51-5
88-05
52-18
81*40
67-5
115-41
68-39
106-69
3(3 0
61-55
36-47
56-90
52-0
88-90
52-68
82*19
68*0
116-27
68-89
107-48
3B-5
62*40
30-98
57-69
52-5
89*76
53-19
82-98
68-5
117T2
69*40
108-27
37-0
63*26
37-48
58-48
53-0
90-61
53-70
83-77
69-0
117-98
69*91
109-06
37*5
64*11
37-99 *
59-27
53-5
91-47
54-20
84-56
69-5
118-83
70-41
109-85
38-0
64*97
38-50
60-06
540
92-32
54-71
85*35
70-0
119-69
70*92
110-64
38-5
65-82
39-00
60-85
54*5
93-18
55-22
86-14
70-5
120-53
71-43
111-43
39*0
66-68
39-51
61-04
55-0
94-03
55-72
86-93
71-0
121-39
71-93
112*23
39-5
67-53
40-02
62-43
55-5
94-89
56-23
87-72
71-5
122-24
72-44
113*02
40-0
68-39
40 52
63-22
56-0
95-74
56-74
88-52
7*2-0
123-10
72-95
113-81
40-5
69-24
41-03
64-01
56-5
96-60
57-24
89-31
72*5
123-95
73-45
114-60
41-0
70-10
41-54
64-81
57-0
97-45
57-75
90-10
73-0
124-81
73*96
115*39
41-5
70-95
42-04
65-60
57-5
98-31
58-26
90-89
73-5
125-66
74-47
116*18
42-0
71-81
42-55
66-39
58-0
99-16
58 76
91-68
740
126-52
74-97
116-97
42-5
72-66
43-06
67-18
58-5
100-02
59-27
92-47
74-5
127-37
75-48
117-7G
43-0
73-52
43-57
67-97
59-0
100-87
59-77
93-26
75-0
128 23
75-99
118*55
43-5
74-37
44-07
68*76
59-5
101-73
60-28
94-05
75-5
129-08
76-49
119-34
44-0
75-23
44-58
69-55
60-0
102-58
60-79
94-84
76-0
129-94
77-00
120-13
44-5
76-08
45-08
70-34
60-5
103-44
61-30
95-63
76*5
130-79
77-51
120-92
450
76-95
45-59
71-13
61 0
104-30
61-80
96-42
77-0
131-65
78-01
221-71
45-5
77-80
46-10
71-92
61-5
105-15
62-31
97 21
77-5
132-50
78-52
122-50
The first column contains percentages of soda, calculated on the correct atomic weight—31. These also represent whatare known in France as Gay-Lussac ’s Degrees.
The second column contains the amounts of carbonate of soda corresponding to the soda in the first column. Soda ashis sold in Germany, Russia , &c., by the percentage of carbonate of soda it contains.
The third column gives the corresponding percentages of soda according to the English test, which is based on the oldatomic weight of soda, 32, still retained as a trade custom in England.
The fourth column shows the corresponding degrees of Decroizilles' Alkalimeter. These degrees represent the numberof parts of monohydrated sulphuric acid (oil of vitriol) which can be neutralized by 100 parts of the sample under examination.Decroizilles’ degrees are used in France and some other parts of the Continent.
Note.—III the commercial testing of samples of soda ash and alkali, all the soda neutralized by test acid is taken intoaccount, and reckoned as soda in the mode of stating the results shown in the first and third columns, as carbonate of soda,as shown in the second column, and as degrees, as shown in the fourth column.
Loss of Soda in Leblanc's Process .—This constantlyoccurs from a variety of causes, which are mainlythe following:—1. Incomplete conversion of sodiumchloride into sulphate. 2. Incomplete decompositionof sodium sulphate in the ball-furnace, and re-forma-tion of the same in the lixiviating tanks, &c. 3.
Mechanical carrying away of sodium salts into theflues. 4. Volatilization of sodium salts as such, oras reduced sodium (this source of loss has beenproved to be of the most insignificant character).5. Formation of sodium salts, which later on donot form the “available” soda, such as sulphide,