multiplied by 0007, the nitrogen equivalent of 1 N 20 c.c. sulphuric acid. As 003 grm. of asparagin was taken, the percentage of nitrogen obtained is readily found. The known amount of nitrogen in crystallised asparagin is 18.67 per cent., and the result obtained by experiment should be within 0-2 per cent. If the result is not satisfactory the experiment should be repeated until accuracy is obtained. Determination of the "Non-coagulable Albuminoids" in Malt. - Digest 25 grms. of the finely ground malt in 250 c.c. distilled water for three hours at about 15.5° (60° F.), stirring the mixture occasionally. Filter, and measure 100 c.c. of the filtrate into a suitable beaker or flask, and boil for about twenty minutes to throw out of solution all the coagulable nitrogenous bodies. Transfer the solution and precipitate to a 100 c.c. measuring flask and, after cooling, make up to the original volume of 100 c.c. Filter, and measure 10 c.c. of the filtrate into a Jena glass flask or beaker. Evaporate to dryness on the water bath, and add 10 c.c. sulphuric acid and 5 grms. potassium sulphate. Heat the mixture, at first gently, until the first violent action is over, and afterwards strongly, until it is decolourised. Transfer to a distilling apparatus, and proceed as already described in the analysis of asparagin. The nitrogen found, after making the necessary correction, is the amount of nitrogen from 1 grm. of malt; from this the amount from 100 grms. of the malt is at once obtained. On the assumption that all the nitrogen found is combined as albuminoids, this number should then be multiplied by the factor 6.3. The factor 6.3 is based on the consideration that the average amount of nitrogen contained in proteids is about 16 per cent.; but the use of the factor 6.3 should be considered as a conventional arrangement, for the nitrogen in proteids varies very considerably, and, moreover, much of the soluble nitrogen of malt exists in combination as amides and bodies other than proteids, concerning which we have very little exact knowledge at present. This, however, does not detract from the value of the determination of "non-coagulable albuminoids" when used comparatively in the analytical examination of malts. When the student is learning the process described above he should conduct his experiments in duplicate in order to check the accuracy of his manipulation. Determination of the "Ready-formed Carbohydrates" of Malt.-Digest 25 grms. of the finelyground malt with 250 c.c. distilled water for three hours at 15° to 18° (60° to 65° F.). Filter, and measure 100 c.c. of the filtrate into a suitable beaker or flask, and boil it for about twenty minutes to throw out of solution all the coagulable bodies. Transfer the solution and precipitate to a 100 c.c. measuring flask, and after cooling make up to the original volume of 100 c.c. Filter, and determine the specific gravity of the filtrate. Calculate the amount of dry solids in 100 c.c. of the 1 filtrate by using the factor 0.386, which is assumed to represent the weight of 1 grm. of these solids when in solution. The amount of dry solids obtained is derived from 10 grms. of malt, and therefore ten times the amount represents the total solids derived from 100 grms. of malt. The method usually adopted to determine the amount of "ready-formed carbo-hydrates " present in the total solids is as follows: It is assumed that the total solids are a mixture of "non-coagulable albuminoids," soluble ash, acid, and "ready-formed carbo-hydrates". Then, if the albuminoids, ash, and acid have been determined experimentally, the sum of the quantities found is subtracted from the total solids, and the difference is supposed to represent the "ready-formed carbo-hydrates" of the malt. If the albuminoids, ash, and acid are not determined experimentally, an average correction for these constituents of the total solids may be made in the following manner: If the total solids are 18.5 per cent., 35 is subtracted, and for each variation of 0.7 per cent. of solids from this amount 0.1 is added to, or subtracted from, 3.5 previous to its employment as a correction. The results of determinations of "ready-formed carbohydrates" obtained by this method must not be regarded as accurate measures of quantity, but they are of value in malt 10.386 is the factor for cane-sugar, but a portion only of the 'ready-formed carbo-hydrates" of malt is cane-sugar. analysis for purposes of comparison. The same purposes would, however, be attained equally well and by simpler means if the "total solids" only were determined, but as the method of estimating the "ready-formed carbo-hydrates" just described is very generally adopted, it is better at present to conform to common usage for the sake of uniformity. It should also be noticed that in the preparation of the cold water extract of malt for the above process it is assumed that diastase has no action on starch during the three hours in which the malt is soaking in cold water. This is not quite accurate, for a slight but perceptible action on the starch takes place. If the cold water mash is made feebly alkaline the action of the diastase is arrested, and a more accurate measure of the "total solids" is obtained, but it is not usual to employ alkali. Determination of the Soluble Ash and the Colour of Malt. Both these determinations may be made on the 10 per cent. cold water extract prepared for the determination of the "readyformed carbo-hydrates ". 1. Determination of the Soluble Ash.-Evaporate in a weighed platinum dish 25 c.c. of the boiled and filtered solution prepared for the "readyformed carbo-hydrate" determination. Ignite the dry residue gently with an ordinary Bunsen flame until it is thoroughly carbonised, and afterwards heat in a muffle furnace until the residual ash is quite white. Cool in a desiccator and weigh. Calculate the amount of ash found as a percentage on the original malt. 2. Determination of the Colour of the Malt.Determine the colour in the one-inch cell of a Lovibond "tintometer" by means of the series of yellowish-brown tinted glasses known as Series No. 52. Reflected light from the porcelain reflector of the tintometer should be employed. Some analysts prefer to determine the colour of malt in an ordinary hot mash of known specific gravity, and refer it by calculation to a standard gravity of 1055.5° (20 lb.). Analyse the colour of the malt by means of the standard red and yellow glasses of the tintometer, and express the result in terms of red and yellow. The "Saccharification " Test.—This test is intended to measure the time in which complete saccharification of a malt mash takes place when the mash is made under normal conditions. Ten grms. of the ground malt are mixed with 100 c.c. of water at 68° (154° F.) and kept in a water bath at 66° (151° F.), the mash being stirred occasionally. In fifteen minutes about 5 c.c. of the mash are withdrawn and filtered through a small filter, and the filtrate, after cooling, is tested with iodine solution for the presence of starch. If starch is found the test is repeated at intervals of five minutes until the reaction of iodine with starch is no longer observed. The time taken for the complete saccharification of the mash is then noted. When the student is familiar with the methods of malt analysis described above he should analyse several samples of malt of different character, making the following determinations :— Extract. Moisture. Diastatic power. Non-coagulable albuminoids. |