[Report of the Medical Officer of Health for Stepney].

  • Stepney (London, England). Metropolitan Borough.
Date:
[1932]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: [Report of the Medical Officer of Health for Stepney]. Source: Wellcome Collection.

Provider: City of London, London Metropolitan Archives

    78/114 (page 74)
    74 Of the above, samples P 47, P 48 and T 57 are deficient in solids-not-fat, the percentages of fat are very high particularly for the month of May. Under present conditions with regard to the supply of milk from cowsheds the afternoon milk will always be considerably richer in fat than the morning supply and morning unbulked milk will be liable to be below the standard. During the year this apparatus has been obtained in order to obtain more certain evidence of the addition of water to milk. The method depends on the fact that genuine milk from healthy cows, whatever its chemical composition, freezes at a point which is within a known range. The method is official in Holland and in America for the detection of watered milk. The Hortvet Cryoscope. The freezing point of milk, as determined by means of the Hortvet apparatus ranges from —0.535° C. to —0.560° C. In Holland a depression of less than 0.53° C. is regarded as definite proof of adulteration. In America the added water is calculated on an average figure of —0.55° C. and a tolerance of 3 per cent. of added water allowed unless this figure is exceeded; this is the same as fixing a limit figure of —0.533° C. Some of the results obtained are given below and these show that useful information in doubtful and other cases of adulteration may be obtained. An average figure of —0.54° C. has been taken as a basis for calculation. Table N. Number. Fat per cent. Solids-not fat per cent. Deficient in Solids-not-fat per cent. = Added water. Hortvet.. Freezing Point. Calculated added water. Calculated original Solids-non fat. L 105 3.25 8.58 None -0.525° C 2.8 8.83 E 11 3.60 8.35 1.8 -0.509° C. 5.7 8.85 M 97 3.50 8.32 2.1 -0.511° C. 5.4 8.80 C 65 3.56 8.14 4.2 -0.502° C. 7.0 8.75 C 81 3.23 7.94 6.6 -0.493° C. 8.7 8.70 Column 4 in the above table shows the amount of added water calculated from the legal minimum of 8.5 per cent. of solids-not-fat. The amount of water so obtained is usually an under estimate of the truth as genuine com mercial milk will normally contain more than the legal minimum of 8.5 per cent. of solids-not-fat; the added water required to dilute this milk to the legal minimum of 8.5 per cent. is not included.