To be added to the ob served indication. To be subtracted from the observed indication. To be added to the ob served indication. TABLE IV.-Correction to be applied to the reading of the alcoholometer for different temperatures. 59 .15 .15 ..... 60 .65 45 .50 .30 .15 63 .20 .20 .20 .85 .90 .95 1.00 1.00 1. 05 1.10 1.10 1.10 1. 15 1.15 .80 .83 .90 .90 .90 .90 .90 .60 . 40 .40 .40 .20 45 .45 45 .65 .65 .85 .85 70 1.35 1.40 1.55 1.55 1.65 1.75 1.85 To be subtracted from the observed indication. DETERMINATION OF THE ALCOHOL. 1. Fill the measuring cylinder to the upper mark with the liquid to be tested (having previously ascertained the temperature of the liquid and the reading of the Balling saccharometer in the liquid), the bottom of the meniscus 1 being on a level with the mark, then empty the measured liquid into the still, letting it drain as completely as possible, then fill the cylinder with one-half of the original volume (the lower mark) with water, and rinse it out, pouring the water into the contents of the still. The measuring of both volumes must be exact. 2. Close the still and make all the connections tight, fill the condenser with cold water, and light the alcohol lamp. 3. Continue the distillation until the original volume taken has been collected in the receiver. Put out the light. Mix the contents of the receiver thoroughly. Insert the alcoholometer and take the reading of the thermometer and hydrometer. Be careful not to carry the distillation further than filling the receiver to the mark. The distillation may be stopped one or two drops before the distillate has reached the mark and the volume brought to the mark with water. 4. If the distillation is hurried so that the liquid foams and the distillate becomes colored the operation must be stopped, the still and condenser thoroughly cleaned, and another volume of the liquid taken. It will generally be found that after half the liquid is distilled the distillate will become cloudy or milky, but such cloudiness does not affect the specific gravity essentially. 5. Take the reading of the alcoholometer and thermometer, and correct the reading of the former for the observed temperature according to Table IV. Then: Corrected reading of the alcoholometer multiplied by the specific gravity of absolute alcohol corresponding to this reading, as found in Table III, and the product divided by the specific gravity of the wine, corresponding to the corrected reading of the Balling saccharometer as found in Table II, equals the percentage by volume of the alcohol in the original wine. METHODS OF SUGAR ANALYSIS. By the term " 'sugar analysis" it is understood that the analyses of all the common saccharine substances, viz, juices, sugar, molasses, sirup, starch sugar, and honey are embraced. In the following directions an attempt will be made to indicate the general principles which should guide the practice of sugar analysis, together with sufficient detail to enable these analyses to be carried out with accuracy and uniformity. The principal components to be determined in the substances mentioned above In sugar or melada.--Weigh from 2 to 5 grs. into a flat dish (nickel or platinum) and dry at the temperature of boiling water for three hours; cool in a desiccator and weigh; return to the oven and dry for an hour. If on weighing there is only a slight The surface of the liquid as seen from above is not quite level, as it rises at the side of the flask and around the hydrometer stem. The rising at the sides give the surface a crescent shape, hence the name "meniscus." The horns of the crescent rise above the level surface of the liquid, hence the direction to look across the bottom of the meniscus, where the horns do not prevent a clear view of the level portion of the surface. change of weight, the process may be considered finished; otherwise the drying must be continued until the loss of water in one hour is not greater than 0.20 per cent. In honey or molasses.-Proceed as above, using only 1 to 2 grs. of substance. DENSITY AND TOTAL SOLIDS. The density of juices, sirups, etc., is most conveniently determined by means of Beaume's or Brix's hydrometer or areometer, preferably with the latter, as the graduations of the scale give close approximations to the percentages of total solids. The Brix spindle should be graduated to tenths, the divisions of the scale being of sufficient length to enable the analyst to note exactly the point to which the stem sinks in the liquid. It is therefore desirable, for accuracy, that the range of degrees recorded by each individual spindle be as limited as possible, this end being best secured by the employment of sets, consisting of not less than three spindles. The solutions should be as nearly as possible of the same temperature as the air at the time of reading, and if the variation from the standard temperature of the graduation of the spindle amounts to more than 1° C., compensation therefor must be made by reference to the table of corrections for temperature on page 114, Tucker's Sugar Analysis. Care should be observed, in taking the density of a juice, to allow it to stand in the cylinder until all air bubbles have escaped, before reading the spindle. When it is desired to accurately determine the specific gravity of the sample, a specific-gravity bottle or picnometer of 50 cc. capacity is employed, and the weight of the amount required to fill the bottle at 15.5° C., divided by 50, gives its correct specific gravity. When the temperature varies from the standard temperature for specific gravities, the weight of the juice must be compared with an equal volume of water weighed at the same temperature. The per cent of total solids can be approximately ascertained directly from the reading of the Brix hydrometer; or, knowing the reading of the Beaumé spindle, or the specific gravity of the sample, by reference to the table on pages 116-118 Tucker's Sugar Analysis, the desired percentage can be obtained. In order to accurately estimate the proportion of total solids in a juice or sirup, from 1 to 3 grs. (according to the density of the liquid) are run into a porcelain dish or glass schaelchen, containing about 2 grs. of finely powdered ignited silica. The whole is then placed on a water bath and heated until the contents are apparently dry, after which it is transferred to an air bath and dried to a constant weight at a temperature not exceeding 110° C. The weight of the dish and silica subtracted from the weight of the dish and contents after drying, gives total solids. ASH. (a) Take 5 or 10 grs. of the material (sugar, molasses, honey) in a platinum dish1 of 50 to 100 cc. capacity; heat at 100° C. until the water is expelled, and then slowly until intumescence ceases. The dish is then placed in a muffle and heated at low reduess until a white ash is obtained. (b) Soluble ash.-Digest the ash with water, filter through a Gooch crucible, wash with hot water, dry the residue at 100° C., and weigh. The difference of weights equals soluble ash. (c) Use 50 mgs. of zinc oxide to 25 grs. of molasses or 50 grs. of sugar. Incoporate thoroughly by adding dilute alcohol, and mixing; dry, and ignite as above. Deduct the weight of zinc used from the weight of ash. (d) Carbonize the mass at a low heat, dissolve the soluble salts with hot water, burn the residual mass as above, add the solution of soluble salts, and evaporate to dryness at 100° C.; ignite gently, cool in a desiccator, and weigh. (e) Saturate the sample with H2SO1, dry, ignite gently, then burn in a muffle at a low redness. If the substance contains tin or any other metal capable of uniting with platinum, a dish made of some other material must be used, 11202-No. 31-15 (f) Dissolve 10 grs. of sugar in hot water and filter to remove sand, etc.; evaporate the filtrate and washings to dryness; carefully carbonize, and extract with hot water until there is no longer any reaction for chlorine. Dry and ignite the residue; weigh as insoluble ash. Add the soluble portion, treat with HCl in slight excess, and evaporate to dryness. Heat until all free HCl is driven off; take up with H2O and a little HCl, filter and wash. The residue is silica. Add NH4OH to the filtrate, boil and filter, wash the residue, which is iron and alumina. To the filtrate add (NH4)2C2O4; evaporate to dryness; ignite and moisten with (NH4)2CO3 and re-ignite; dissolve in water, filter, and wash. The residue on the filter represents carbonates of lime and magnesia. Evaporate the filtrate to a small bulk, add (NH4)2CO3, and evaporate to dryness; drive off the excess of ammonia cautiously and weigh. This gives the alkalis as carbonates, and this weight, added to the insoluble ash, formerly determined, gives the total carbonate ash. ALTERNATE METHOD. To avoid the correction of one-tenth, as proposed by Scheibler, and one-fifth as proposed by Girard and Violette, when sugars are burned with H2SO4, Boyer suggests incineration with benzoic acid, as giving the real quantity of mineral matter without correction. The benzoic acid is dissolved in alcohol of 90 per cent, 25 grs. of the acid to 100 cc. of alcohol; 5 grs. of the sugar is weighed in a capsule and moistened with 1 cc. of H2O. The capsule is heated slowly, in order to caramelize the sugar without carbonizing it; 2 cc. of the benzoic acid is next added, and the capsule warmed until all the alcohol is evaporated; the temperature is then elevated until the sugar is converted into carbon. The decomposing benzoic acid produces abundant vapors which render the mass extremely porous, especially if a circular motion is imparted to the capsule. The slow heating is continued until all the benzoic acid is volatilized. The carbon obtained is voluminous and of a brilliant black color. The incineration is accomplished in a muffle at a low red heat. The capsule should be weighed quickly when taken from the desiccator, in order to avoid the absorption of water by the alkaline carbonates. Benzoate of ammonia may be employed instead of benzoic acid, and the analyst should previously assure himself that neither the acid nor the ammonia salt leaves a residue on incineration. In addition to giving the mineral matters directly, this method permits the determination of their composition also, a matter of no small importance. NITROGENOUS BODIES. Any of the methods adopted by the association for the estimation of nitrogen may be used. REDUCING SUGAR. Reagent, alkaline copper solution. (Fehling, Violettc.) 34.64 grs. of pure crystallized copper sulphate. 187.00 grs. of tartrate of soda and potash. 78.00 grs. of caustic of soda. Dissolve the CuSO,+5H2O in water, and make up to 1,000 cc. at the average temperature at which the analyses are to be made. Mix the solutions of Rochelle salts and caustic soda, and make up to 1,000 cc. In practice use equal volumes of each reagent. Processes (volumetric).—(a) The solution to be examined should contain about 1 per cent of reducing sugar. To 10 cc. of the copper solution and 10 cc. of the alkali, in a large test tube or casserole, add 20 cc. of water and boil. Add the sugar solution in approximately the proper quantity to reduce the copper, and boil for exactly two minutes. If, on standing for a moment, the solution is still blue, add more sugar solution and re-boil. When no longer able to distinguish any residual copper by the eye, suck a few drops of the boiling hot liquid into a Wiley-Knorr end reaction tube, and test the filtrate for Cu with ferrocyanide of potassium solution and acetic acid. If preferred the Ross method, using filter paper, may be used. If copper be still present, add the sugar solution little by little, boil, and re-test until no copper is found. Having thus determined the approximate quantity of sugar solution to be used, repeat the test twice, adding immediately each time almost the entire quantity of sugar solution necessary to complete reduction. (b) Gravimetric.—Take 25 cc. of copper solution of the following composition: 34.639 grs. of CuSO4+5H2O in 500 cc. of water, add in an Erlenmeyer flask 25 cc. of alkali solution made as follows: Add 50 cc. of a sugar solution of such strength as to leave a part of the copper unreduced; heat quickly to the boiling point, and boil for exactly two minutes; add 100 cc. of recently boiled, cold, distilled water. The liquid is poured at once into a filter tube made of hard glass, with asbestos diaphragm (an ordinary extraction tube is well adapted for this purpose). The asbestos film should be previously moistened. Bring finally all the separated suboxide into the tube with the help of a feather brush, and wash with 300 to 400 cc. of boiling water, afterward with 20 cc. of absolute alcohol, and finally with ether; then dry, heat to low redness to convert into oxide, and to destroy any organic matter. The copper may also be weighed in the metallic state after reduction in a stream of dry hydrogen. The tube should in all cases be kept in a desiccator before weighing. (c) (Gravimetric.) Reagents: 34.639 grs. of CuSO4+5H2O 125.000 grs. of NaOH 173.000 grs. of Rochelle salts in 500 cc. of water. Process.In a beaker of 250 cc. capacity place 25 cc. each of the reagents, and 50 cc. of water. Heat to boiling and add 25 cc. of the solution to be tested, which should contain about 1 per cent of reducing sugar (dextrose, levulose). Boil for exactly two minutes, decant into a Gooch crucible, wash by decantation with 100 cc. of boiling-hot water, keeping the cuprous oxide in the beaker constantly covered. Place the beaker containing the cuprous oxide in place of the one receiving the wash water and dissolve the CuO on the Gooch crucible in a fine stream of HNO3; wash until all Cu(NO3)2 is removed. Transfer the whole of the nitrate from the beaker to a tared platinum dish, add a little H2SO4, and evaporate over a steam bath until all HNO3 is expelled, and the Cu is converted into CuSO4; connect with a battery of four gravity cells, and allow the electrolytic action to continue for three hours, or until all the Cu is deposited. (Connect the dish with the zinc pole of the battery.) Pour off the acid solution, adding water until every trace of H2SO, is removed; wash with 95 per cent alcohol, and finally with absolute alcohol; ignite the residual alcohol, cool in a desiccator, and weigh; calculate the sugar reduced from the weight of metallic copper by the following factors: (1) Multiply the weight of copper by 0.5698 for the weight of invert sugar. (2) Multiply the weight of copper by 0.5808 for the weight of anhydrous dextrose. Sucrose.-(Optical method, to be used when the sugar is approximately pure. A small filter, the diameter of which need not exceed 2 inches, is folded as for ordinary filtrations, and is immersed, point down, in the hot supernatant liquid, the apex of the filter being just beneath the surface of the solution. A portion of the liquid at once filters through, and is removed from the interior of the filter by means of a small dropping pipette, consisting of a small glass tube with finely drawn out point and provided with a rubber bulb at the upper extremity. The liquid is readily taken up and expelled from the pipette by alternately compressing and relax. ing pressure upon the bulb. A fresh filter is used for each filtration, and the pipette is rinsed after each portion of the solution is tested, |