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ance was found in connection with other ingredients or with the various
stages of the manufacture, apart from the points set out in the next paragraph.
While there was a good deal of handling of materials at various stages
of the process of manufacture, the risks seemed to be rendered largely negligible
by the degree and duration of exposure to heat during the baking. One
obvious exception to this was to be noted in the process of adding the gelatine
bone stock to the pies. Here there was no heating subsequent to the addition
of the gelatine and seasoning to the hot bone stock, as a preliminary to
running the mixture into the cavity of the pie. Further, the gelatine bone
stock mixture was made in a metal vessel, drained at the bottom by a tap
which, unless subjected to the most careful and thorough cleansing after
use, would be liable to retain a trace of the stock, so that an infected stock
could conceivably, by this means, contaminate subsequent supplies of stock
run out from the same vessel. While ordinary care was used in cleansing
this vessel, the chanoe of pollution through this source was evidently not
apparent to the employees responsible, so that this method of possible contamination
could not be ruled out of court.
Thus several possibilities of contamination were here evident:—
(1) Pollution through infected veal, ham, or bones—unlikely, owing to the
length of boiling and subsequent simmering (approaching the boiling point)
to which the stock was subjected.
(2) Pollution during the process of adding the gelatine, the latter having
conceivably been infected, either
(a) before arrival in the bakery : Dr. Wilkinson, of the Ministry of Health,
was good enough to undertake investigation of the processes of manufacture
and storage of the gelatine at the factory in London which supplied it to
the Croydon firm ;
(b) during storage at the bakery. The particular supply of powdered
gelatine in use at the time of manufacture of the infected pies (August 25th27th)
had been in use—and had been the only stock in use—for a number of
months previously. It was stored in a large uncovered tin, the mouth of
which was close to the end of a shelf on which jam, cakes, and disused
utensils were stored—i.e., was in a position accessible to, and likely to be
visited by mice, which might thus be a factor in contaminating it by the
deposit of infected excreta. Further, the tin in which the powdered gelatine
was stored had previously been used for powdered whole egg, and had been
dry cleaned, but not washed or scalded after removal of the powered egg
and before introduction of the gelatine. In some previous outbreaks of
paratyphoid (B) fever, the prepared egg used in the process of manufacture
of incriminated foodstuffs was under suspicion, owing to the fact that the
white of egg may be infected during the act of laying by a fowl suffering
from intestinal disease. Here, therefore, was still another—perhaps rather
remote—possibility of contamination of the gelatine;
(c) by the hands of the employee responsible for getting the gelatine from
the storage tin, for mixing it with water, and for adding it to the hot bone
stock. It has already been noted that during the baking of the two batches of
pies so far incriminated, a worker transferred temporarily from other work in
the bakery had been concerned in this particular process, during the absence
of the regular hand on holiday; but that no evidence of illness in this temporary
hand could be discovered. It will be seen later that another means
of human contamination of the gelatine at this stage was, in fact, possible
though this was not recognised at the time of the investigation, owing to the
list of employees having been incomplete in one particular.