SOIL ARTHROPOD S A N I L I N G
17
(kerosene) as a source of heat and operated for a summer season in Lapland, the second using bottled-gas (butane - or pentane in cold conditions) which has not been tried in the field at the time of writing. Both
these extractors are similar to the canister extractor (Macfadyen, 1961)
in general layout and, unless ambient temperatures are very low, both
require a flow of cold water for cooling purposes (usually fairly easily
arranged from a stream under expedition conditions). The paraffinoperated extractor contains a hot water-bath (in place of the electric
heater) which is supplied with a circulation of hot water from a separate
boiler heated by a wick type boiling stove (“Valor 65 S”). The flow and
return pipes should be of thick transparent PVC tubing (e.g. E.R.P.
tubing from Esco Rubber Ltd, London), and these and the boiler insulated with glass wool. An apparatus to deal with forty-eight sampleunits coiisumed about 3 gal (14 1) of paraffin per week. The main problems under field conditions arose from the difficulty of ensuring that the
paraffin heater worked efficiently (with a blue flame) and without boiling the water. I n other words a smaller stove run with a higher flame
would have been easier to control and might have burned less paraffill.
The gas-burning extractor (Fig. 1 ) uses a ;in thick aluminium hot
plate in place of the rather cumbersome boiler and water circulation
and is, therefore, more compact. The gas burners are incorporated in
the sides of the apparatus which are lined with heat-resisting plastic
(Tuffnol, Asp Brand). An apparatus to treat thirty samples burns about
174 lb (8 kg) of butane per week. The relative advantages of burning
butane, at about two and a half times the price of paraffin but weighing
about the same in cylinders are largely a matter of expedition logistics
against the greater convenience of the gas.
If the gas is to be kept a t or below 0” C propane should be used instead of butane; this has about 75% the heat of combustion of butane
and is more expensive. The entire apparatus including core sampling
tools, canisters and rings weighs 40 lb (18 kg).
The use of vertical-sided canisters in place of funnels in extracting
small soil cores has the advantage of removing all possibility of loss of
animals on the sides of the funnel, of reducing the chances of loss due
to worms, spider’s webs and other obstructions in the constriction of
of the funnel and of presenting a large aqueous surface for the maintenance of a high humidity beneath the sample. Two corresponding
disadvantages are that removal of material from the canisters requires more skill and larger quantities of fluid than in the case of a vial
on the end of the funnel and also that the large liquid area necessitates
the use of a non-volatile fluid to ensure that animals will not be deterred
from leaving the sample. With very little practice the “catch” in a
17
(kerosene) as a source of heat and operated for a summer season in Lapland, the second using bottled-gas (butane - or pentane in cold conditions) which has not been tried in the field at the time of writing. Both
these extractors are similar to the canister extractor (Macfadyen, 1961)
in general layout and, unless ambient temperatures are very low, both
require a flow of cold water for cooling purposes (usually fairly easily
arranged from a stream under expedition conditions). The paraffinoperated extractor contains a hot water-bath (in place of the electric
heater) which is supplied with a circulation of hot water from a separate
boiler heated by a wick type boiling stove (“Valor 65 S”). The flow and
return pipes should be of thick transparent PVC tubing (e.g. E.R.P.
tubing from Esco Rubber Ltd, London), and these and the boiler insulated with glass wool. An apparatus to deal with forty-eight sampleunits coiisumed about 3 gal (14 1) of paraffin per week. The main problems under field conditions arose from the difficulty of ensuring that the
paraffin heater worked efficiently (with a blue flame) and without boiling the water. I n other words a smaller stove run with a higher flame
would have been easier to control and might have burned less paraffill.
The gas-burning extractor (Fig. 1 ) uses a ;in thick aluminium hot
plate in place of the rather cumbersome boiler and water circulation
and is, therefore, more compact. The gas burners are incorporated in
the sides of the apparatus which are lined with heat-resisting plastic
(Tuffnol, Asp Brand). An apparatus to treat thirty samples burns about
174 lb (8 kg) of butane per week. The relative advantages of burning
butane, at about two and a half times the price of paraffin but weighing
about the same in cylinders are largely a matter of expedition logistics
against the greater convenience of the gas.
If the gas is to be kept a t or below 0” C propane should be used instead of butane; this has about 75% the heat of combustion of butane
and is more expensive. The entire apparatus including core sampling
tools, canisters and rings weighs 40 lb (18 kg).
The use of vertical-sided canisters in place of funnels in extracting
small soil cores has the advantage of removing all possibility of loss of
animals on the sides of the funnel, of reducing the chances of loss due
to worms, spider’s webs and other obstructions in the constriction of
of the funnel and of presenting a large aqueous surface for the maintenance of a high humidity beneath the sample. Two corresponding
disadvantages are that removal of material from the canisters requires more skill and larger quantities of fluid than in the case of a vial
on the end of the funnel and also that the large liquid area necessitates
the use of a non-volatile fluid to ensure that animals will not be deterred
from leaving the sample. With very little practice the “catch” in a