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country and in Germany and the United States. After a rather long preliminary
period, gas formation began and although not at first combustible, the gas, after a
time, contained a large proportion of combustible constituents, the calorific value
of gas obtained during this period being about 750 British thermal units per cubic
foot, some samples reaching 800 British thermal units.
The production of carbon dioxide during the early stages of digestion can be
greatly reduced by the addition of air-slaked lime to the fresh sludge. The production
of gas goes down to inappreciable amounts in cold weather. During the acid
stage of digestion much separation of solid matter takes place, but as the separated
matter cannot be relied upon either to settle to the bottom or rise to the surface no
practical means of dewatering has yet been based on this observation. These experiments
were on a very small scale but the results are sufficiently promising to show the
desirability of further investigation on a works scale.
Fertilisers
and feeding
stuffs.
During the year, 272 samples of fertilisers and feeding stuffs for cattle and
poultry have been examined in connection with the provisions of the Fertilisers and
Feeding Stuffs Act, 1926, by the chemist who is agricultural analyst for those parts
of the county which do not come within the purview of the City Corporation or the
Port Sanitary Authority. These samples may be tabulated as under:—
Samples of feeding stuffs 219
Incorrect guarantees 62
Samples of fertilisers 53
Incorrect guarantees 9
Total: Samples 272
Incorrect guarantees 71
It is clear that, apart from cases of careless manufacture, many sellers and
some makers of these materials do not realise the importance of stating the amounts
of specified ingredients in the form prescribed, which allows variation within reasonable
limits, but are inclined to fix their own limits. Further, there is considerable
evidence (in cases where, apparently, manufacturers of these products have them
analysed from time to time) of inexpertness in basing a guarantee on the analyses.
In some cases, it appears that the composition of a material made of several ingredients
is calculated merely from the supposed composition of these ingredients,
leading to percentages, e.g., of oil and albuminoids being guaranteed which are not
found in the manufactured article. These facts show to what a great extent the
1906 Act had become disregarded, as most of these points were in that Act and
should have been familiar to sellers.
The form of limit allowed, i.e., ± 1/N of the amount of the constituent men
tioned in the statutory statement (N=5, 6, 8,10 or 20—according to the material)
has the curious result that, at times, it is necessary to describe a material as not
complying with the statutory statement when, in fact, it contains more of a desired
or less of an undesirable constituent than the upper or the lower limit respectively
allows. The reason of the limits being fixed so as to affect both excesses and deficits
is that under the first (1893) Act, materials were sometimes guaranteed to contain
say, only 1 per cent. of the constituent for which they were bought, and an accompanying
statement expressed the seller's belief that they contained, say, 26 per
cent. which they usually did. The safeguards against vexatious or misinformed
prosecution are so full under the present Act that no fear of this kind need arise.
Occasionally statements given in accordance with the statute are given in such
a form as to be almost incapable of fulfilment. For example, the composition of a
fish meal was so given that, to comply, it would have to contain less than 4 per cent.
of water, which is unlikely.
A committee is, it is understood, considering several questions of this kind, with
a view to modification of the regulations.