Filtration, inverted

The filtration should be conducted in a dry-box or using an inverted funnel-nitrogen flow, whichever is more convenient. 

Oil-Base Muds. Oil-base muds contain oil as the continuous phase and water as the dispersed phase. Oil-base muds contain less than 5% (by volume) water, while oil-base emulsion muds (invert emulsions) have more than 5% water in mud. Oil-base muds are usually a mixture of diesel fuel and asphalt the filtrate is oil. 

A slow stream of dry nitrogen was passed through an inverted funnel that was placed over the filtration apparatus. 

In order to remove the substance from the filter plate after filtration the funnel is inverted over a basin or watch-glass and all the material is transferred to the latter with the help of a thin glass rod- or copper wire the glass button is pushed out from its lower end. The plate is removed with forceps, but the paper not before it is dry. The material which adheres to the funnel is removed without loss by scraping with a small, obliquely cut piece of thin cardboard. 

The checkers used an inverted funnel connected to a source of dry nitrogen to provide an inert atmosphere for the filtration. The filtration was carried out as completely as possible directly beneath the inverted funnel through which a rapid stream of nitrogen flowed. 

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