A Modified Filtration System for Palynological Preparations

Abstract

THE use of sintered glass filter plates has found wide application in the standard maceration techniques adopted by many palynologists. This form of filter plate is particularly useful for the separation of organic residues consisting of miospores, pollen grains, cuticles, etc., from the alkali-soluble ulmins produced during the oxidation of bituminous coals and carbonaceous shales. The efficiency of the filtration process naturally depends on maintaining the pores of the filter plate free from obstruction by solid particles. In the case of coal preparations little difficulty has been experienced on account of the relatively large grain size of the organic residue and the small quantities of material present in the filter funnel. However, in the case of the shales, their alloch-thonous origin has frequently resulted in the presence of considerable quantities of fine-grained, sub-colloidal organic debris in the post-oxidation residues. The grain size of this organic ‘background’ material is generally less than 8µ. and particles of this size would normally pass through the filter plate. On account of the large quantities present, the pores of the plate become progressively blocked, so reducing the efficiency and increasing the duration of the filtration process. To some extent this position has been alleviated by the use of small amounts in the funnel and frequent application of distilled water by the operator. This method is time consuming and often fails to produce the best results possible as the obstructing particles have been drawn down into the pores of the filter plate and cannot be effectively removed by washing from above.