Principles and practice of agricultural analysis. Volume 3 (of 3), Agricultural products

by Harvey Washington Wiley

Fig. 125. Improved Ebullioscope.

A second apparatus, exactly similar to the one described, is conveniently used for measuring the changes in barometric pressure during the process of the analysis. The temperature of the vapor of boiling water having been first determined, the beer or wine is placed in F, and the temperature of the vapor of the boiling liquid determined after the temperature of the air layer between E and F reaches about 90°, measured on the thermometer C. By using alcoholic mixtures of known strength the depression for each changing per cent of alcohol is determined for each system of apparatus employed, and this having once been done, the percentage of alcohol in any unknown liquid is at once determined by inspecting the thermometer, the bulb of which is immersed in the vapor from the boiling liquid. In the apparatus [figured], a depression of 0°.8 is equivalent to one per cent of alcohol by volume. Full directions for the manipulation of the apparatus may be found in the paper cited above.

623. Total Fixed Matters.—The residue left on evaporating a fermented beverage to dryness is commonly known as extractive matter, or simply extract. It is composed chiefly of unfermented carbohydrates, organic acids, nitrogenous bodies, glycerol and mineral substances. Hydrochloric and sulfuric acids may also be found therein. If any non-volatile preservatives have been used in the sample, such as borax, salicylates and the like, these will also be found in the solid residue. The bodies which escape are water, alcohols, ethers and essential oils. The character of the residue left by wines and beers is evidently different. In each case it should contain typical components which aid in judging of the purity of the sample. For instance, in beers the substitution for malt of carbohydrate bodies comparatively free of proteids, produces a beer containing a deficiency of nitrogenous bodies. Pure malt beer will rarely have less than one-half of a per cent of proteids, while beer made largely of glucose, rice or hominy grits, will have a much smaller quantity. First will be described below the methods of determining the fixed residue left on evaporation, and thereafter the processes for ascertaining its leading components.

624. Methods of the Official Chemists.—Two methods are in use by the official chemists for determining the fixed solids in fermented beverages.[638] They are as follows:

Direct Method.—Fifty cubic centimeters of the sample are weighed, placed in a platinum dish about eighty millimeters in diameter and capable of holding about seventy-five cubic centimeters and evaporated on the steam bath to a sirupy consistence. The residue is heated for two and a half hours in a drying oven at the temperature of boiling water and weighed.

In Sweet Wines.—Ten cubic centimeters of the liquor are weighed and diluted to 100 with water. Fifty cubic centimeters of this solution are evaporated as described above.

Optional Method.—Fifty cubic centimeters of the sample are placed in a platinum or porcelain dish and evaporated on the steam bath until the volume is reduced to one-third. The dealcoholized liquid is washed into a fifty cubic centimeter flask, cooled and made up to the original volume. It is mixed thoroughly and the specific gravity ascertained with a pyknometer, hydrostatic balance or an accurately standardized hydrometer. The percentage of total solids is obtained from the appended table. The column on the left of the specific gravity gives the percentage of extract in a wine, as calculated by Hager, and that on the right the percentage of extract in a beer or wort, as calculated by Schultze. According to Baumert, however, Schultze’s table gives results which approximate more closely the data obtained by direct estimation than does Hager’s.

Tables of Hager and Schultze for
the Determination of Extract
by the Indirect Method.

Hager.	Specific gravity.	Schultze.
0.84	1.0038	1.00
0.86	1.0039	1.02
0.88	1.0040	1.05
0.90	1.0041	1.08
0.92	1.0042	1.10
0.94	1.0043	1.13
0.96	1.0044	1.15
0.98	1.0045	1.18
1.00	1.0046	1.21
1.02	1.0047	1.23
1.04	1.0048	1.26
1.06	1.0049	1.29
1.08	1.0050	1.31
1.10	1.0051	1.34
1.12	1.0052	1.36
1.15	1.0053	1.39
1.17	1.0054	1.41
1.19	1.0055	1.44
1.22	1.0056	1.46
1.25	1.0057	1.49
1.27	1.0058	1.51
1.30	1.0059	1.54
1.32	1.0060	1.56
1.34	1.0061	1.59
1.37	1.0062	1.62
1.39	1.0063	1.64
1.42	1.0064	1.67
1.44	1.0065	1.69
1.46	1.0066	1.72
1.48	1.0067	1.74
1.50	1.0068	1.77
1.52	1.0069	1.79
1.55	1.0070	1.82
1.57	1.0071	1.84
1.59	1.0072	1.87
1.61	1.0073	1.90
1.64	1.0074	1.92
1.66	1.0075	1.95
1.68	1.0076	1.97
1.70	1.0077	2.00
1.72	1.0078	2.02
1.75	1.0079	2.05
1.77	1.0080	2.07
1.79	1.0081	2.10
1.82	1.0082	2.12
1.84	1.0083	2.15
1.86	1.0084	2.17
1.88	1.0085	2.20
1.90	1.0086	2.23
1.92	1.0087	2.25
1.94	1.0088	2.28
1.96	1.0089	2.30
1.98	1.0090	2.33
2.00	1.0091	2.35
2.03	1.0092	2.38
2.05	1.0093	2.41
2.07	1.0094	2.43
2.09	1.0095	2.46
2.11	1.0096	2.48
2.14	1.0097	2.51
2.16	1.0098	2.53
2.18	1.0099	2.56
2.21	1.0100	2.58
2.23	1.0101	2.61
2.25	1.0102	2.64
2.27	1.0103	2.66
2.30	1.0104	2.69
2.32	1.0105	2.71
2.34	1.0106	2.74
2.36	1.0107	2.76
2.38	1.0108	2.79
2.40	1.0109	2.82
2.42	1.0110	2.84
2.44	1.0111	2.87
2.46	1.0112	2.89
2.48	1.0113	2.92
2.50	1.0114	2.94
2.52	1.0115	2.97
2.54	1.0116	2.99
2.57	1.0117	3.02
2.59	1.0118	3.05
2.61	1.0119	3.07
2.64	1.0120	3.10
2.66	1.0121	3.12
2.68	1.0122	3.15
2.70	1.0123	3.17
2.72	1.0124	3.20
2.75	1.0125	3.23
2.77	1.0126	3.25
2.79	1.0127	3.28
2.82	1.0128	3.30
2.84	1.0129	3.33
2.86	1.0130	3.35
2.88	1.0131	3.38
2.90	1.0132	3.41
2.92	1.0133	3.43
2.94	1.0134	3.46
2.96	1.0135	3.48
2.98	1.0136	3.51
3.00	1.0137	3.54