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supervision, the standards of hygiene of the individual salesman varying considerably as does the
amount of supervision exercised by the companies owning or renting the vans.

The bacterial cleanliness of ice cream is measured by the application of the methylene blue
reduction test. The test affords a simple and valuable means for the routine grading of the product
and has proved useful in indicating when further investigation is called for into the practices of
manufacturers, distributors and retailers. The recommended provisional grading based on this test
in which readings are taken half-hourly is:—
Provisional Grade
1
2
3
4
Time taken to reduce methylene blue
Fails to reduce in 4 hours
2½—4 hours
½ — 2 hours
0
In interpreting these results, note should be taken of the comments made in the monthly bulletin
(October 1950) of the Ministry of Health and Public Health Laboratory Service which stated that
"owing to the numerous factors governing the hygienic quality of ice cream, it is unwise to pay too
much attention to the bacteriological results of any single sample. Judgement should be based
rather on a series of samples. It is suggested that over a six-monthly period, 50 per cent of a vendor's
samples should fall into grade 1, 80 per cent into grades 1 and 2 and not more than 20 per cent
into grade 3 and none into grade 4".
During the year attention continued to be given to premises where ice cream is sold loose,
either over the counter or as a sweet with a restaurant meal. In spite of the advice given over the
years concerning the care needed in the handling of loose ice cream, it is perhaps a little disappointing
that nearly a third of the samples taken were reported as being Grades 3 or 4.
Liquid Egg
Considerable use is now made by the baking trade of bulk liquid egg. Sampling of this was carried
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