CALCULATION OF TOTAL SOLIDS OF MILK. The relation existing between the various components of the milk is such as to make possible the calculation of the percentage of solids not fat, and total solids, in a sample of milk when the fat-content and the specific gravity (lactometer reading) of the milk are known. Several formulas have been worked out by chemists in different parts of the world, by the application of which the total solids may be calculated from the percentage of fat and the specific gravity of the milk. We give here Babcock's formula, published in the twelfth report of Wisconsin Experiment Station. (100 1.07535f where s specific gravity of the milk and ƒ per cent of fat found. When s and ƒ are known the per cent of solids not fat in the milk may be calculated by means of this formula. In order to avoid making the lengthy calculations in every case, tables for solids not fat are given on the following pages; results obtained by the formula given above, or by means of the following tables, will come within a couple of tenths from the actual percentages present, when reasonable care is taken in the determinations of fat and specific gravity (or lactometer reading). Short formulas. The following formulas for solids not fat and for total solids are derived from the data given in the following tables. L = lactometer reading at 60° F. (specific gravity X 1000 1000); f = per cent of fat in Rule: To find per cent of solids not fat, add two tenths of the per cent of fat to one fourth of the lactometer reading. To find per cent of total solids, add one and two tenths times the per cent of fat to one fourth of the lactometer reading. Results obtained by using the short formulas will agree very closely with those derived from the general formula, or from the tables published below, and may be safely relied upon in practical work. The tables cover a range of .0 to 6.0 per cent of fat, and from 26 to 36 lactometer reading. If intermediate values for ƒ and L are at hand, corrections in the per cent of solids not fat found may easily be made, with .02 per cent for every tenth of one per cent of fat, and .25 per cent for every lactometer degree. Example: Given ƒ = 3.67 per cent and L = 32.5. By referring to the table we find that f=3.6_and_L 32 will give 8.73 per cent of solids not fat; correction for fat-content, .o1 per cent (3.67 being nearer 3.65 than 3.70), and for lactometer reading, 12 per cent; corrected per cent solids not fat, 8.86. = TABLE SHOWING PER CENT OF SOLIDS NOT FAT, Corresponding to Quevenne Lactometer Readings and Per Cent of Fat. (ВАВСОСК.) Per Ct. of Fat. : 36789 6.50 6.75 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.75 9.00 9.06 6.60 6.85 7.10 7.35 7.60 7.85 8.10 8 35 8.60 8.85 9.10 6.62 6.87 7.12 7.37 7.62 7.87 8.12 8.37 8.62 8.87 9.12 6.64 6.89 7.14 7.39 7.64 7.89 8.14 8.39 8.64 8.89 9.14 .8 6.66 6 91 7.16 7.41 7.66 7.91 8.16 8.41 8.66 8.91 9.16 6.68 6.93 7.18 7.43 7.68 7.93 8.18 8.43 8.68 8.93 9.18 .9 1.0 1. I 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.I 2.2 2.3 2.4 6.70 6.80 7.05 7.30 7.55 7.80 8.05 8.30 8.55 8.80 9.05 9.30 9.39 1.9 2.0 6.90 7.15 7.40 7.65 7.90 8.15 8.40 8.66 8.91 9 16 9.41 2.1 2.2 2.3 2 4 3.2 2.5 7.00 7.25 7.50 7.75 8.00 8.25 8.50 8.76 9.01 9 26 9.51 7.20 7.45 7.71 7.96 8.21 8.46 8.71 8.96 9.22 9.47 9.72 7.30 7.56 7.81 8.06 8.31 8.56 8.81 9.06 9.32 9.57 9.83 4.I 7.32 7.58 7.83 8.08 8.33 8.58 8.83 9.09 9.34 9.59 9.85 4.2 7.34 7.60 7.85 8.10 8.35 8 60 8.85 9.11 9.36 9.62 9.87 4.3 7.36 7.62 7.87 8.12 8.37 8.62 8.88 9.13 9.38 9.64 9.89 7.38 7.64 7 89 8.14 8.39 8.64 8.90 9.15 9.40 9.66 9.91 4.4 4.0 4.I 4.2 4.3 4.4 Per Ct. of Fat. 4.5 4.6 4.7 4.8 TABLE FOR SOLIDS NOT FAT—(Continued). Lactometer Readings at 60° Fahr. 26 27 28 29 30 31 32 33 34 35 36 7.40 7.66 7.91 8.16 8.41 8.66 8.92 9.17 9.42 9.68 9.93 Per Ct. of Fat. 4.5 4.6 4.7 4.8 4.9 4.9 5.0 5.1 5.2 5.3 5.4 7.51 7.76 8.01 8.26 8.51 8.76 9.02 9.27 9.52 9.78 10.03 5.0 9.54 9.80 10.05 5.I 9.56 5.2 5.3 5.4 5.6 5.7 5.8 5.9 5.5 7.61 7.86 8.11 8.36 8.62 8.87 9.12 9.38 9.63 7.63 7.88 8.13 8.39 8.64 8.89 9.15 9.40 9.65 7.65 7.90 8.15 8.41 8.66 8.91 9.17 9.42 9.67 7.67 7.92 8.17 8.43 8.68 8.94 9.19 9.44 9.69 7.69 7.94 8.20 8.45 8.70 8.96 9.21 9.46 9.71 6.0 7.71 7.96 8.22 8.47 8.72 8.98 9.23 9.48 9.73 MILK STANDARDS IN DIFFERENT STATES, CITIES, AND COUNTRIES. per ct. per ct. [9.0] 1893,255 1883 Vermont. 12.5 [3.25] 9.25 1888,108 in May and June. 12.0 3.0 [9.0] Massachusetts 13.0 [3.7] 9.3 1886,318 in May and June. 12.0 ADULTERATION OF MILK. The legal standards adopted in the different States of the Union determine the limits for fat or solids, below which the milk offered for sale must not fall. Where no control sample can be taken of a suspected sample of milk, calculations of the extent of the adulteration practised are made on basis of the legal standard in each State. Whenever possible, a control sample should be secured on the premises of the suspected party, and subjected to analysis. If the control sample contains appreciably less fat or solids not fat than did the suspected sample, the latter was skimmed or watered, or both skimmed and watered. SKIMMING.-I. If a sample is skimmed, the following formula will give the number of pounds of fat abstracted from 100 lbs. of milk: Fat abstracted = x = legal standard for fat-f, . (I) f being the per cent of fat in the suspected sample. In this and following formulas the percentages found in the control samples, if such are at hand, are always to be substituted for the legal standards. II. The following formula will give the per cent of fat abstracted, calculated on the total quantity of fat originally found in the milk: WATERING.-I. If a sample is watered, the calculations are most conveniently based on the percentage of solids not fat in the milk: Per cent extraneous water in milk s being the per cent of solids not fat in the suspected sample. Example.-A sample contains 8.5 per cent of solids not fat; if the legal standard for solids not fat be 9 per cent, 8.5 X 100 5.6, will give the per cent of extraneous ΙΟΟ 9 water in the suspected sample of milk. |